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Abstract
BACKGROUND In 2013 the Food and Drug Administration (FDA) claimed the existence of new data showing women to be at risk for excessive daytime sedation and impaired driving proficiency following bedtime doses of zolpidem. The putative explanation was the reduced metabolic clearance of zolpidem and higher morning blood concentrations in women compared to men. The FDA acted to reduce the recommended dosage for women down to 50% of the dose for men. No other regulatory agency worldwide has taken similar action. METHODS Gender effects on zolpidem pharmacokinetics, pharmacodynamics, adverse effects, clinical efficacy, and driving performance were evaluated through a further analysis of data from a previous study, together with a literature review. RESULTS Women had on average 35% lower apparent clearance of zolpidem than men (236 vs 364 mL/min, P < 0.001). This difference was not explained by body weight. In some laboratory studies, women had greater functional impairment than men taking the same dose, but in all studies active drug was not distinguishable from placebo at 8 hours after oral dosage. On-the-road driving studies likewise showed no evidence of driving impairment in men or women at 8 hours after 10 mg of oral immediate-release zolpidem. No clinical trial demonstrated a gender-related difference in clinical efficacy or adverse reactions, and there was no evidence of a particular risk to women. CONCLUSIONS Dosage reduction in women is not supported by available scientific evidence, and may in fact lead to underdosing and the consequent hazard of inadequately treated insomnia.
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Functional and effective brain connectivity for discrimination between Alzheimer’s patients and healthy individuals: A study on resting state EEG rhythms. Clin Neurophysiol 2017; 128:667-680. [DOI: 10.1016/j.clinph.2016.10.002] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 09/09/2016] [Accepted: 10/01/2016] [Indexed: 11/19/2022]
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Chen X, Broeyer F, de Kam M, Baas J, Cohen A, van Gerven J. Pharmacodynamic response profiles of anxiolytic and sedative drugs. Br J Clin Pharmacol 2017; 83:1028-1038. [PMID: 27922194 DOI: 10.1111/bcp.13204] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 11/21/2016] [Accepted: 11/22/2016] [Indexed: 02/04/2023] Open
Abstract
AIM Centrally-acting acutely anxiolytic drugs, such as benzodiazepines, barbiturates and gabapentinoids, affect various central nervous system (CNS) functions, which reflects not only their anxiolytic effects but also neuropsychological side-effects. To validate the pharmacodynamic biomarkers for GABA-ergic anxiolytics, this study determined the pharmacodynamics of two anxiolytics and a nonanxiolytic control, and linked them to their anxiolytic and sedative effects, during an anxiety-challenge study day. METHODS Twenty healthy volunteers were randomized in this placebo-controlled, double-blind, four-way cross-over study with single-dose alprazolam (1 mg), diphenhydramine (50 mg), pregabalin (200 mg) or placebo. The Neurocart was used between repeated fear-potentiated startle assessments. Thus, the potential influence of anxiety on CNS pharmacodynamic markers could be examined. RESULTS Compared to placebo, VAScalmness increased with alprazolam (2.0 mm) and pregabalin (2.5 mm) but not with diphenhydramine. Saccadic peak velocity (SPV) declined after alprazolam (-57 ° s-1 ) and pregabalin (-28 ° s-1 ), more than with diphenhydramine (-14 ° s-1 ); so did smooth pursuit. The average responses of SPV and smooth pursuit were significantly correlated with the drug-induced increases in VAScalmness . The SPV-relative responses of VASalertness , body-sway and adaptive-tracking also differed among alprazolam, pregabalin and diphenhydramine. CONCLUSIONS Compared with the antihistaminergic sedative diphenhydramine, alprazolam and pregabalin caused larger SPV reduction, which was correlated with simultaneous improvement of subjective calmness, during a study day in which anxiety was stimulated repeatedly. The different effect profiles of the three drugs are in line with their pharmacological distinctions. These findings corroborate the profiling of CNS effects to demonstrate pharmacological selectivity, and further support SPV as biomarker for anxiolysis involving GABA-ergic neurons. The study also supports the use of prolonged mild threat to demonstrate anxiolytic effects in healthy volunteers.
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Affiliation(s)
- Xia Chen
- Phase I Unit, Clinical Pharmacology Research Center, Peking Union Medical College Hospital, Beijing, 100032, China.,Centre for Human Drug Research, Leiden, The Netherlands
| | | | | | - Joke Baas
- Department of Experimental Psychology, Faculty of Social Sciences, Utrecht University, The Netherlands
| | - Adam Cohen
- Centre for Human Drug Research, Leiden, The Netherlands
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Greenblatt DJ, Abourjaily PN. Pharmacokinetics and Pharmacodynamics for Medical Students: A Proposed Course Outline. J Clin Pharmacol 2016; 56:1180-95. [DOI: 10.1002/jcph.732] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 03/03/2016] [Indexed: 11/11/2022]
Affiliation(s)
- David J. Greenblatt
- Program in Pharmacology and Experimental Therapeutics, Sackler School of Graduate Biomedical Sciences; Tufts University School of Medicine; Boston MA USA
| | - Paul N. Abourjaily
- Departments of Pharmacy and Medicine; Tufts Medical Center; Boston MA USA
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do Rego JL, Vaudry D, Vaudry H. The non-benzodiazepine anxiolytic drug etifoxine causes a rapid, receptor-independent stimulation of neurosteroid biosynthesis. PLoS One 2015; 10:e0120473. [PMID: 25785994 PMCID: PMC4364751 DOI: 10.1371/journal.pone.0120473] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 01/23/2015] [Indexed: 11/19/2022] Open
Abstract
Neurosteroids can modulate the activity of the GABAA receptors, and thus affect anxiety-like behaviors. The non-benzodiazepine anxiolytic compound etifoxine has been shown to increase neurosteroid concentrations in brain tissue but the mode of action of etifoxine on neurosteroid formation has not yet been elucidated. In the present study, we have thus investigated the effect and the mechanism of action of etifoxine on neurosteroid biosynthesis using the frog hypothalamus as an experimental model. Exposure of frog hypothalamic explants to graded concentrations of etifoxine produced a dose-dependent increase in the biosynthesis of 17-hydroxypregnenolone, dehydroepiandrosterone, progesterone and tetrahydroprogesterone, associated with a decrease in the production of dihydroprogesterone. Time-course experiments revealed that a 15-min incubation of hypothalamic explants with etifoxine was sufficient to induce a robust increase in neurosteroid synthesis, suggesting that etifoxine activates steroidogenic enzymes at a post-translational level. Etifoxine-evoked neurosteroid biosynthesis was not affected by the central-type benzodiazepine (CBR) receptor antagonist flumazenil, the translocator protein (TSPO) antagonist PK11195 or the GABAA receptor antagonist bicuculline. In addition, the stimulatory effects of etifoxine and the triakontatetraneuropeptide TTN, a TSPO agonist, were additive, indicating that these two compounds act through distinct mechanisms. Etifoxine also induced a rapid stimulation of neurosteroid biosynthesis from frog hypothalamus homogenates, a preparation in which membrane receptor signalling is disrupted. In conclusion, the present study demonstrates that etifoxine stimulates neurosteroid production through a membrane receptor-independent mechanism.
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Affiliation(s)
- Jean Luc do Rego
- Institute for Research and Innovation in Biomedicine (IRIB), University of Rouen, Mont-Saint-Aignan, France
- Regional Platform for Cell Imaging (PRIMACEN), International Associated Laboratory Samuel de Champlain, University of Rouen, Mont-Saint-Aignan, France
| | - David Vaudry
- Institute for Research and Innovation in Biomedicine (IRIB), University of Rouen, Mont-Saint-Aignan, France
- Regional Platform for Cell Imaging (PRIMACEN), International Associated Laboratory Samuel de Champlain, University of Rouen, Mont-Saint-Aignan, France
- Neurotrophic Factors and Neuronal Differentiation team, Inserm U982, University of Rouen, Mont-Saint-Aignan, France
| | - Hubert Vaudry
- Institute for Research and Innovation in Biomedicine (IRIB), University of Rouen, Mont-Saint-Aignan, France
- Regional Platform for Cell Imaging (PRIMACEN), International Associated Laboratory Samuel de Champlain, University of Rouen, Mont-Saint-Aignan, France
- Neurotrophic Factors and Neuronal Differentiation team, Inserm U982, University of Rouen, Mont-Saint-Aignan, France
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Greenblatt DJ, Harmatz JS, Singh NN, Steinberg F, Roth T, Moline ML, Harris SC, Kapil RP. Gender differences in pharmacokinetics and pharmacodynamics of zolpidem following sublingual administration. J Clin Pharmacol 2013; 54:282-90. [PMID: 24203450 DOI: 10.1002/jcph.220] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 10/28/2013] [Indexed: 11/10/2022]
Abstract
The effect of dose and gender on the pharmacokinetics (PK) and pharmacodynamics (PD) of zolpidem after administration of a buffered zolpidem sublingual tablet (ZST; Intermezzo®, Purdue Pharma L.P., Stamford, CT, USA) was evaluated in healthy non-elderly male and female volunteers. Subjects received a single morning dose of ZST (1.0, 1.75, and 3.5 mg) or placebo in a four-way crossover study. In male and female subjects zolpidem PK were linear, with area under the curve (AUC) proportional to dose, and apparent oral clearance and elimination half-life independent of dose. However, AUC averaged 40% to 50% higher in females than in males receiving the same dose. The gender effect was incompletely explained by body weight. In females, ZST produced PD changes consistent with benzodiazepine agonist effects, particularly at the 3.5-mg dose. For several PD variables, PD effects were significantly related to plasma zolpidem concentrations when data were aggregated across subjects. However, there was variability in response among individuals. In males, PD effects of zolpidem seldom differed from placebo regardless of plasma concentration. The findings confirm that zolpidem clearance is lower in females than in males. PD effects of zolpidem from ZST are greater in female subjects, due to a combination of higher plasma concentrations and greater intrinsic sensitivity.
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Affiliation(s)
- David J Greenblatt
- Department of Integrative Physiology and Pathobiology, Tufts University School of Medicine, Boston, MA, USA
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Greenblatt DJ, Legangneux E, Harmatz JS, Weinling E, Freeman J, Rice K, Zammit GK. Dynamics and Kinetics of a Modified-Release Formulation of Zolpidem: Comparison With Immediate-Release Standard Zolpidem and Placebo. J Clin Pharmacol 2013; 46:1469-80. [PMID: 17101746 DOI: 10.1177/0091270006293303] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Modified-release (MR) zolpidem was developed to maintain effective plasma concentrations during the 3- to 6-hour post-dosage interval, corresponding to the middle portion of the typical sleep interval. Modified-release zolpidem (12.5 mg), standard immediate-release (IR) zolpidem (10 mg), and placebo were compared in a double-blind, single-dose, 3-way crossover daytime study of healthy volunteers (n = 70 completers). Effect areas for electroencephalographic beta amplitude during 0 to 8 hours and 3 to 6 hours after dosage were greater for MR compared to IR (P < .001). The digit-symbol substitution test and sedation rating scales behaved similarly. MR and IR did not differ in effects at 8 hours post-dosage nor in halflife or clearance. Time of peak plasma concentration (tmax) was significantly longer for MR (2.4 vs 2.0 hours, P < .004), and dose-normalized peak plasma concentration (Cmax) was lower (12.2 vs 14.0 ng/mL/mg, P < .001). MR zolpidem also had greater area under the plasma concentration curve (AUC) during the 3- to 6-hour interval (P < .001). Thus, MR zolpidem produces sustained plasma levels compared to IR, with resulting enhancement of pharmacodynamic effects in the 3- to 6-hour post-dosage interval.
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Affiliation(s)
- David J Greenblatt
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA.
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Lowry E, Woodman RJ, Soiza RL, Hilmer SN, Mangoni AA. Drug Burden Index, Physical Function, and Adverse Outcomes in Older Hospitalized Patients. J Clin Pharmacol 2013; 52:1584-91. [DOI: 10.1177/0091270011421489] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Verster JC, Roth T. Blood drug concentrations of benzodiazepines correlate poorly with actual driving impairment. Sleep Med Rev 2012; 17:153-9. [PMID: 22884949 DOI: 10.1016/j.smrv.2012.05.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Revised: 05/14/2012] [Accepted: 05/14/2012] [Indexed: 10/28/2022]
Abstract
BACKGROUND The use of benzodiazepine receptor agonists can significantly impair driving performance. The aim of this review was to determine if there is a relation between blood concentrations of these drugs and the degree of driving impairment. METHODS A literature search was conducted to identify driving studies that examined the effects of benzodiazepine receptor agonists. Studies were included if the on-the-road driving test was employed, using the standard deviation of lateral position (SDLP), i.e., the weaving of the car, as primary outcome measure. RESULTS A total of 24 studies were identified that employed the on-the-road driving test to examine driving performance after administration of benzodiazepine receptor agonists. Eleven of these studies (45.8%) measured blood drug concentrations after the on-the-road driving test was performed. Technical reports of some of these studies provided individual data on blood drug concentrations and ΔSDLP (the ΔSDLP difference between drug and placebo). While group differences in concentrations were found as evidenced by significant effects of dose and time of driving since time of drug ingestion, no significant relationship between individual blood drug concentrations and ΔSDLP was found in any of the studies. CONCLUSION While group mean average ΔSDLP and blood drug concentration sometimes correlate, individual differences in blood drug concentrations of benzodiazepine receptor agonists correlate poorly with driving impairment. From the currently available data, it must be concluded that there are no significant relationships between individual blood drug concentration and ΔSDLP. Future driving studies should assess blood drug levels as a standard procedure, to enable further research into the relationship between blood drug concentration and performance impairment.
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Affiliation(s)
- Joris C Verster
- Utrecht Institute for Pharmaceutical Sciences, Division of Pharmacology, Utrecht University, Universiteitsweg 99, Utrecht, The Netherlands.
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10
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Abstract
Pharmacokinetics and pharmacodynamics can provide a useful modeling framework for predicting drug activity and can serve as a basis for dose optimization. Determining a suitable biomarker or surrogate measure of drug effect for pharmacodynamic models can be challenging. The electroencephalograph is a widely-available and non-invasive tool for recording brainwave activity simultaneously from multiple brain regions. Certain drug classes (such as drugs that act on the central nervous system) also generate a reproducible electroencephalogram (EEG) effect. Characterization of such a drug-induced EEG effect can produce pharmacokinetic/pharmacodynamic models useful for titrating drug levels and expediting development of chemically-similar drug analogs. This paper reviews the relevant concepts involved in pharmacokinetic/pharmacodynamic modeling using EEG-based pharmacodynamic measures. In addition, examples of such models for various drugs are organized by drug activity as well as chemical structure and presented.
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Abstract
We aimed to assess the relationship between Drug Burden Index (DBI), a risk assessment tool that measures anticholinergic and sedative medication exposure and cognitive performance, and cognitive impairment in older people. The study population consisted of community-dwelling older men, 70 years or older, living in Sydney, Australia. The Addenbrooke's Cognitive Examination (ACE) and the Trail Making Task (TMT) cognitive tests were performed, and participants were categorized as having intact cognition, mild cognitive impairment, or dementia using clinical diagnostic criteria. The analyses were restricted to participants with English-speaking background (n = 987) and to the subgroup whose cognition was intact (n = 887). In the study group, DBI exposure was not associated with poorer performance on the ACE (odds ratio [OR], 0.98; 95% confidence interval [CI], 0.66-1.47) or the TMT (OR, 0.71; 95% CI, 0.40-1.24) tests, after controlling for covariates. Similarly, DBI exposure was not associated with cognitive impairment (OR, 1.34; 95% CI, 0.83-2.16). There was no association between increasing DBI scores and poorer performance on any of the outcomes. On subgroup analysis of cognitively intact subgroup, DBI exposure or increasing DBI scores were not associated with poorer performance on the ACE or the TMT tests. In this study of community-dwelling older men, DBI was not associated with limitations on objective cognitive performance measures or with a clinical diagnosis of mild cognitive impairment or dementia.
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Turkmen S, Backstrom T, Wahlstrom G, Andreen L, Johansson IM. Tolerance to allopregnanolone with focus on the GABA-A receptor. Br J Pharmacol 2011; 162:311-27. [PMID: 20883478 DOI: 10.1111/j.1476-5381.2010.01059.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Many studies have suggested a relationship between stress, sex steroids, and negative mental and mood changes in humans. The progesterone metabolite allopregnanolone is a potent endogenous ligand of the γ-amino butyric acid -A (GABA-A) receptor, and the most discussed neuroactive steroid. Variations in the levels of neuroactive steroids that influence the activity of the GABA-A receptor cause a vulnerability to mental and emotional pathology. There are physiological conditions in which allopregnanolone production increases acutely (e.g. stress) or chronically (e.g. menstrual cycle, pregnancy), thus exposing the GABA-A receptor to high and continuous allopregnanolone concentrations. In such conditions, tolerance to allopregnanolone may develop. We have shown that both acute and chronic tolerances can develop to the effects of allopregnanolone. Following the development of acute allopregnanolone tolerance, there is a decrease in the abundance of the GABA-A receptor α4 subunit and the expression of the α4 subunit mRNA in the ventral-posteriomedial nucleus of the thalamus. Little is known about the mechanism behind allopregnanolone tolerance and its effects on assembly of the GABA-A receptor composition. The exact mechanism of the allopregnanolone tolerance phenomena remains unclear. The purpose of this review is to summarize certain aspects of current knowledge concerning allopregnanolone tolerance and changes in the GABA-A receptors.
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Affiliation(s)
- Sahruh Turkmen
- Department of Obstetrics & Gynaecology, Sundsvall County Hospital, Sweden.
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de Haas SL, Schoemaker RC, van Gerven JMA, Hoever P, Cohen AF, Dingemanse J. Pharmacokinetics, pharmacodynamics and the pharmacokinetic/ pharmacodynamic relationship of zolpidem in healthy subjects. J Psychopharmacol 2010; 24:1619-29. [PMID: 19648220 DOI: 10.1177/0269881109106898] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Zolpidem is one of the most frequently prescribed hypnotics, as it is a very short-acting compound with relatively few side effects. Zolpidem's short duration of action is partly related to its short elimination half-life, but the associations between plasma levels and pharmacodynamic (PD) effects are not precisely known. In this study, the concentration-effect relationships for zolpidem were modelled. Zolpidem (10 mg) was administered in a double-blind, randomised, placebo-controlled trial to determine PD and pharmacokinetics (PK) in 14 healthy volunteers. Zolpidem was absorbed and eliminated quickly, with a median T(max) of 0.78 h (range: 0.33-2.50) and t(1/2) of 2.2 h. Zolpidem reduced saccadic peak velocity (SPV), adaptive tracking performance, electroencephalogram (EEG) alpha power and visual analogue scale (VAS) alertness score and increased body sway, EEG beta power and VAS 'feeling high'. Short- and long-term memory was not affected. Central nervous system effects normalised more rapidly than the decrease of plasma concentrations. For most effects, zolpidem's short duration of action could be adequately described by both a sigmoid E(max) model and a transit tolerance model. For SPV and EEG alpha power, the tolerance model seemed less suitable. These PK/PD models have different implications for the mechanism underlying zolpidem's short duration of action. A sigmoid E(max) model (which is based on ligand binding theory) would imply a threshold value for the drug's effective concentrations. A transit tolerance model (in which a hypothetical factor builds up with time that antagonises the effects of the parent compound) is compatible with a rapid reversible desensitisation of GABAergic subunits.
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Affiliation(s)
- S L de Haas
- Centre for Human Drug Research, Leiden, The Netherlands.
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Misaka S, Uchida S, Imai H, Inui N, Nishio S, Ohashi K, Watanabe H, Yamada S. Pharmacokinetics and pharmacodynamics of low doses of midazolam administered intravenously and orally to healthy volunteers. Clin Exp Pharmacol Physiol 2010; 37:290-5. [DOI: 10.1111/j.1440-1681.2009.05285.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Abstract
This study investigated an anxiety-prone cognitive style (measured by the Anxious Thoughts and Tendencies Questionnaire, AT&T) as a predictor of the acute response to increasing alprazolam plasma levels in panic disorder. Panic disorder patients (n=26) were treated with escalating doses of alprazolam for 4 weeks, then a fixed dose of 1 mg four times a day for 4 weeks. At 0, 1, 2, 3, 4, 6, and 8 weeks, trough alprazolam plasma levels; clinical, self-report, and performance measures; and vital signs were assessed. Panic attack data were from daily diaries. The repeated response measures were analyzed in relation to alprazolam plasma levels using SAS GENMOD, with patients classified as high or low on the baseline AT&T. Panic attacks, anticipatory anxiety, fear, avoidance, overall agoraphobia, the Hamilton Anxiety Rating Scale, and clinicians' global ratings improved with increasing alprazolam plasma levels. Hopkins Symptom Checklist-90 Anger-Hostility; Profile of Mood States Vigor, Confusion, and Friendliness; and speed and accuracy of performance worsened. Patients with high AT&T scores were worse throughout the study on situational panics, fear, avoidance, overall agoraphobia, the Hamilton Anxiety Rating Scale, the Hamilton Rating Scale for Depression, and Clinical Global Improvement; most Hopkins Symptom Checklist-90 clusters; Profile of Mood States Anxiety, Depression, and Confusion; and Continuous Performance Task omissions. We conclude that in panic disorder: (1) alprazolam has a broad spectrum of clinical activity related to plasma levels in individual patients; (2) sedation, disinhibition, and performance deficits may persist for at least a month after dose escalation ends; (3) marked anxiety-prone cognitions predict more symptoms throughout treatment, but do not modify the response to alprazolam and therefore should not influence the choice of alprazolam as treatment.
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Navarro V, Mazoit JX. [Drugs for status epilepticus treatment]. Rev Neurol (Paris) 2009; 165:355-65. [PMID: 19223054 DOI: 10.1016/j.neurol.2008.12.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Accepted: 12/04/2008] [Indexed: 01/16/2023]
Abstract
The pharmacokinetics and pharmacodynamics of major antiepileptic agents are presented. The onset of action and the factors leading to extraction across the blood brain barrier are described as well as the mechanism and extent of metabolism, and the main interactions with other drugs. For each class, the dosing scheme and practical issues related to administration are described, based on evidence when available in the literature.
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Affiliation(s)
- V Navarro
- Unité d'épilepsie, département de neurophysiologie clinique, hôpital de la Pitié-Salpêtrière, AP-HP, Paris, France
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Barbanoj MJ, Urbano G, Antonijoan R, Ballester MR, Valle M. Different acute tolerance development to EEG, psychomotor performance and subjective assessment effects after two intermittent oral doses of alprazolam in healthy volunteers. Neuropsychobiology 2007; 55:203-12. [PMID: 17878744 DOI: 10.1159/000108379] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Accepted: 06/10/2007] [Indexed: 12/20/2022]
Abstract
BACKGROUND/AIMS Benzodiazepines (BZDs) are the most effective of the psychotropic drugs in the treatment of anxiety disorders. Tolerance has been reported for the majority of BZDs after chronic administration. However, little attention has been paid to the possibility that tolerance might be present after the intermittent oral administration of BZDs. The objectives of the present study were to assess tolerance development after the administration of two intermittent single oral doses of alprazolam given 15 days apart in healthy volunteers, and to compare the results obtained using measures from different domains: neurophysiological, psychomotor and subjective. METHODS Twenty-four healthy volunteers received 2 mg of alprazolam orally on two experimental days, 15 days apart. Plasma concentrations and pharmacodynamics (PD) were assessed before drug intake and at different times in the following 24 h. PD was assessed through EEG (relative alpha and relative beta-1 activities), cancellation task (total and correct number of responses) and visual analogue scales (activity and drowsiness). RESULTS No differences were observed in the PKs of alprazolam between occasions. A proteresis was present in both administrations for impairments of psychomotor performance and relative beta-1 activity, whereas it was present only after the second administration for subjective assessments and relative alpha activity. The proteresis on the second occasion was higher than on the first one. CONCLUSIONS The administration of two single oral doses of alprazolam, 2 weeks apart in healthy volunteers, yielded the same PKs on both occasions, but significant changes were observed in the PD profile. Acute tolerance was observed after the second administration. Two patterns of acute tolerance development were obtained: (1) impairments of psychomotor performance and relative beta-1 activity, and (2) subjective assessments and relative alpha activity.
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Affiliation(s)
- M J Barbanoj
- Centre d'Investigació del Medicament, Institut de Recerca HSCSP, Servei de Farmacologia Clinica, Hospital de la Santa Creu i Sant Pau, and Departament de Farmacologia i Terapèutica (UAB), Barcelona, Spain.
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Stetinová V, Kvetina J, Pastera J, Polásková A, Prazáková M. Gliclazide: pharmacokinetic-pharmacodynamic relationships in rats. Biopharm Drug Dispos 2007; 28:241-8. [PMID: 17415747 DOI: 10.1002/bdd.550] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The relationship between the pharmacokinetics of gliclazide and its antidiabetic efficacy were evaluated on the basis of experimental determination of changes with time in the plasma levels of this antidiabetic agent and those of glucose. The experiment included rats with both initial normal glycaemia and alloxan-induced hyperglycaemia (glycaemia increased by a minimum of 30%). Pharmacokinetic and pharmacodynamic parameters were examined in the interval of 30 to 180 min after p.o. administration of a single dose of 25 mg/kg of gliclazide. The drug was administered on day 4, following a single i.v. dose of either 50 mg/kg of alloxan (hyperglycaemic group) or the injection vehicle (control group). Even though the biological availability of gliclazide was similar in both normoglycaemic and hyperglycaemic animals, the gliclazide-induced hypoglycaemizing response was not uniform: until 60 min, the decrease of glycaemia was smaller in animals with alloxan hyperglycaemia (23% decrease at 60 min) in contrast to the normoglycaemic animals (36% decrease at 60 min), at later times, the intensity of this hypoglycaemizing effect of gliclazide persisted in the hyperglycaemic animals, while in the normoglycaemic ones, a reversal of the hypoglycaemizing effect occurred.
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Affiliation(s)
- V Stetinová
- Institute of Experimental Biopharmaceutics, Joint Research Centre of the Czech Academy of Sciences and PRO.MED.CS Praha a.s., Hradec Králové, Czech Republic.
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Jones AW, Holmgren A, Kugelberg FC. Concentrations of scheduled prescription drugs in blood of impaired drivers: considerations for interpreting the results. Ther Drug Monit 2007; 29:248-60. [PMID: 17417081 DOI: 10.1097/ftd.0b013e31803d3c04] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We report the concentrations of scheduled prescription drugs in blood samples from people arrested in Sweden for driving under the influence of drugs (DUID). The investigation covered a 2 year period 2004 (N = 7052 cases) and 2005 (N = 7759 cases) and was prompted by recent legislation stipulating zero-concentration limits in blood for controlled substances. However, prescription drugs are exempt from the zero-limit law provided that the medication was being used in accordance with a doctor's prescription. The blood concentrations of various psychoactive substances were compared with the limits of quantitation of the analytic method used and the so-called therapeutic concentration range according to various reference books and tabulations. Diazepam [N = 1950 (26%)] and nordazepam [N = 2168 (28%)] were the therapeutic agents most frequently identified in these forensic blood samples along with other benzodiazepines such as alprazolam [N = 430 (5.6%)], flunitrazepam [N = 308 (4.0%)], and nitrazepam [N = 222 (2.9%)]. The newer hypnotics, exemplified by zolpidem [N = 148 (1.9%)] and zopiclone [N = 111 (1.5%)], were also high on the list of psychoactive substances identified. Interpreting the concentration of a prescription drug in blood in relation to whether the person had taken an overdose or was abusing the substance in question is not always easy. The age, gender, degree of obesity, and ethnicity of the person concerned; the pharmacokinetic profile of the drug; polymorphism of drug-metabolizing enzymes as well as liver and kidney function and blood hematocrit need to be considered. Among preanalytic factors, stability of the drug in blood after sampling, the type of tubes and preservatives used, the dosage form and route of administration deserve consideration. When therapeutic drug monitoring concentrations are compared with forensic toxicology results, then the plasma-to-whole blood distribution ratio of the drug also needs to be considered. In blood samples from DUID suspects, the concentrations of many commonly used sedatives and hypnotics exceeded the accepted therapeutic limits, which gives an indication of the abuse potential of these types of medications.
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Affiliation(s)
- A W Jones
- Department of Forensic Genetics and Forensic Toxicology, National Board of Forensic Medicine, Artillerigatan 12, Linköping, Sweden.
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Danhof M, de Jongh J, De Lange ECM, Della Pasqua O, Ploeger BA, Voskuyl RA. Mechanism-Based Pharmacokinetic-Pharmacodynamic Modeling: Biophase Distribution, Receptor Theory, and Dynamical Systems Analysis. Annu Rev Pharmacol Toxicol 2007; 47:357-400. [PMID: 17067280 DOI: 10.1146/annurev.pharmtox.47.120505.105154] [Citation(s) in RCA: 203] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mechanism-based PK-PD models differ from conventional PK-PD models in that they contain specific expressions to characterize, in a quantitative manner, processes on the causal path between drug administration and effect. This includes target site distribution, target binding and activation, pharmacodynamic interactions, transduction, and homeostatic feedback mechanisms. As the final step, the effects on disease processes and disease progression are considered. Particularly through the incorporation of concepts from receptor theory and dynamical systems analysis, important progress has been made in the field of mechanism-based PK-PD modeling. This has yielded models with much-improved properties for extrapolation and prediction. These models constitute a theoretical basis for rational drug discovery and development.
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Affiliation(s)
- Meindert Danhof
- Leiden/Amsterdam Center for Drug Research, Division of Pharmacology, Leiden University, 2300 RA Leiden, The Netherlands.
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Nguyen N, Fakra E, Pradel V, Jouve E, Alquier C, Le Guern ME, Micallef J, Blin O. Efficacy of etifoxine compared to lorazepam monotherapy in the treatment of patients with adjustment disorders with anxiety: a double-blind controlled study in general practice. Hum Psychopharmacol 2006; 21:139-49. [PMID: 16625522 DOI: 10.1002/hup.757] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Adjustment Disorders With Anxiety (ADWA) account for almost 10% of psychologically motivated consultations in primary care. The aim of this double-blind randomised parallel group study was to compare (non-inferiority test) the efficacies of etifoxine, a non-benzodiazepine anxiolytic drug, and lorazepam, a benzodiazepine, for ADWA outpatients followed by general practitioners. 191 outpatients (mean age: 43, female: 66%) were assigned to receive etifoxine (50 mg tid) or lorazepam (0.5-0.5-1 mg /day) for 28 days. Efficacy was evaluated on days 7 and 28 of the treatment. The main efficacy assessment criterion was the Hamilton Rating Scale for Anxiety score (HAM-A) on Day 28 adjusted to Day 0. The anxiolytic effect of etifoxine was found not inferior to that of lorazepam (HAM-A score decrease: 54.6% vs 52.3%, respectively, p=0.0006). The two drugs were equivalent on Day 28. However, more etifoxine recipients responded to the treatment (HAM-A score decreased by >or=50%, p=0.03). Clinical improvement (based on Clinical Global Impression scale CGI, Social Adjustment Scale Self-Report SAS-SR, and Sheehan scores) was observed in both treatment arms, but more etifoxine patients improved markedly (p=0.03) and had a marked therapeutic effect without side effects as assessed by CGI, p=0.04. Moreover, 1 week after stopping treatment, fewer patients taking etifoxine experienced a rebound of anxiety, compared to lorazepam (1 and 8, respectively, p=0.034).
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Affiliation(s)
- N Nguyen
- CPCET et Pharmacologie Clinique, Institut des Neurosciences Cognitives de la Méditerranée, Faculté de Médecine, UMR CNRS Université de la Méditerranée, Assistance Publique Hôpitaux de Marseille-Hôpital de la Timone, 13385 Marseille Cedex 5, France
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Greenblatt DJ, Gan L, Harmatz JS, Shader RI. Pharmocokinetics and pharmacodynamics of single-dose triazolam: electroencephalography compared with the Digit-Symbol Substitution Test. Br J Clin Pharmacol 2005; 60:244-8. [PMID: 16120062 PMCID: PMC1884767 DOI: 10.1111/j.1365-2125.2005.02409.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2004] [Accepted: 12/28/2004] [Indexed: 01/22/2023] Open
Abstract
AIMS To investigate whether the electroencephalogram (EEG) directly reflects the CNS effects of benzodiazepines by evaluating the relation of the EEG to plasma drug concentrations and to Digit-Symbol Substitution Test (DSST) scores after a single dose of triazolam, a representative benzodiazepine agonist. METHODS Thirteen healthy male subjects were given 0.375 mg triazolam or placebo in a double-blind crossover study. Plasma samples were collected during 8 h after dosage. Pharmacodynamic effects were measured by DSST and EEG at corresponding times. RESULTS Pharmacokinetic parameters for triazolam were consistent with established values. Compared with placebo, triazolam significantly impaired psychomotor performance on the DSST (P < 0.001) and increased beta amplitude on the EEG (P < 0.002). DSST and EEG changes both closely tracked changes in plasma concentrations over time. The changes for the two measures were highly correlated with each other (r =-0.94, P < 0.001) based on aggregate values at individual time points. However, the variations in area under the curve of pharmacodynamic effect vs. time (AUCeffect) measured by either method did not reflect the variations in plasma AUC across individuals. The individual variability in AUCeffect from the EEG was similar to that measured by the DSST. CONCLUSIONS Both the EEG and the DSST reflect the central benzodiazepine agonist effects of triazolam. Intrinsic variability in both measures is similar.
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Affiliation(s)
- David J Greenblatt
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine and Tufts-New England Medical Center, Boston, MA 02111, USA.
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Venkatakrishnan K, Culm KE, Ehrenberg BL, Harmatz JS, Corbett KE, Fleishaker JC, Greenblatt DJ. Kinetics and dynamics of intravenous adinazolam, N-desmethyl adinazolam, and alprazolam in healthy volunteers. J Clin Pharmacol 2005; 45:529-37. [PMID: 15831776 DOI: 10.1177/0091270004269105] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The pharmacokinetics and pharmacodynamics of adinazolam mesylate (10 mg), N-desmethyl adinazolam mesylate (NDMAD, 10 mg), and alprazolam (1 mg) were investigated in 9 healthy male subjects in a randomized, blinded, single-dose, 4-way crossover study. All drugs were intravenously infused over 30 minutes. Plasma adinazolam, NDMAD, and alprazolam concentrations, electroencephalographic (EEG) activity in the beta (12-30 Hz) range, performance on the Digit Symbol Substitution Test (DSST), and subjective measures of mood and sedation were monitored for 12 to 24 hours. Mean pharmacokinetic parameters for adinazolam, NDMAD, and alprazolam, respectively, were as follows: volume of distribution (L), 106, 100, and 77; elimination half-life (hours), 2.9, 2.8, and 14.6; and clearance (mL/min), 444, 321, and 84. More than 80% of the total infused adinazolam dose was converted to systemically appearing NDMAD. All 3 benzodiazepine agonists significantly increased beta EEG activity, with alprazolam showing the strongest agonist activity and adinazolam showing the weakest activity. Alprazolam and NDMAD significantly decreased DSST performance, whereas adinazolam had no effect relative to placebo. Adinazolam, NDMAD, and alprazolam all produced significant observer-rated sedation. Plots of EEG effect versus plasma alprazolam concentration demonstrated counterclockwise hysteresis, consistent with an effect site delay. This was incorporated into a kinetic-dynamic model in which hypothetical effect site concentration was related to pharmacodynamic EEG effect via the sigmoid E(max) model, yielding an effect site equilibration half-life of 4.8 minutes. The exponential effect model described NDMAD pharmacokinetics and EEG pharmacodynamics. The relation of both alprazolam and NDMAD plasma concentrations to DSST performance could be described by a modified exponential model. Pharmacokinetic-dynamic modeling was not possible for adinazolam, as the data did not conform to any known concentration-effect model. Collectively, these results indicate that the benzodiazepine-like effects occurring after adinazolam administration are mediated by mainly NDMAD.
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Affiliation(s)
- Karthik Venkatakrishnan
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA
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Echizenya M, Mishima K, Satoh K, Kusanagi H, Sekine A, Ohkubo T, Shimizu T, Hishikawa Y. Enhanced heat loss and age-related hypersensitivity to diazepam. J Clin Psychopharmacol 2004; 24:639-46. [PMID: 15538127 DOI: 10.1097/01.jcp.0000144890.45234.e9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Whether elderly people suffer from age-related changes in pharmacokinetics and/or pharmacodynamics with administration of benzodiazepines is still a matter of controversy. We investigated the course of brain function and thermoregulation after oral administration of a standard benzodiazepine, diazepam (DZP), in 8 healthy young men (mean age, 19.8 years; range, 18 to 23 years) and 8 healthy middle-aged and older men (mean age, 60.9 years; range, 53 to 71 years). Placebo or DZP was administered in a single-blind crossover manner to the young men (placebo, 5-mg, 10-mg DZP) and to the older men (placebo, 5-mg DZP), and plasma DZP concentration, choice reaction time, proximal body temperature, and distal body temperature were monitored with high time resolution under a modified constant routine condition to exclude masking effects. Whereas there was no evidence of age-related alterations in pharmacokinetics between the 2 groups, the older subjects, in comparison to the young subjects, showed a more delayed choice reaction time in response to the same plasma DZP level, suggesting that hypersensitivity is related to increased age. DZP at 5 mg in the older subjects induced acute and transient hypothermia to the same degree as that induced by DZP at 10 mg in the young subjects. The distal-proximal body temperature gradient (difference between distal body temperature and proximal body temperature), an indicator of blood flow in distal skin regions, showed strong positive correlation with the delay in choice reaction time in both groups. These findings suggest that hypersensitivity to benzodiazepine in older persons may be due, at least in part, to age-related changes in thermoregulation, especially in the heat loss process.
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Affiliation(s)
- Masaru Echizenya
- Division of Neuropsychiatry, Department of Neuro and Locomotor Science, Akita University School of Medicine, Akita, Japan
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Greenblatt DJ, Ehrenberg BL, Culm KE, Scavone JM, Corbett KE, Friedman HL, Harmatz JS, Shader RI. Kinetics and EEG Effects of Midazolam during and after 1-Minute, 1-Hour, and 3-Hour Intravenous Infusions. J Clin Pharmacol 2004; 44:605-11. [PMID: 15145968 DOI: 10.1177/0091270004265368] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The objective of this study was to evaluate the kinetics and dynamics of midazolam when administered by three different infusion schemes, using electroencephalography to measure pharmacodynamic effects. In a three-way crossover study, 8 volunteers received midazolam (0.1 mg/kg) by constant-rate intravenous infusion. The durations of midazolam infusions for the three trials were 1 minute, 1 hour, and 3 hours. Plasma midazolam concentrations and electroencephalographic (EEG) activity in the 13- to 30-Hz range were monitored for 24 hours. Based on separate analysis of each subject-trial, mean values for volume of distribution and distribution or elimination half-life did not significantly vary. Central compartment volume and clearance differed among the three midazolam infusion trials; however, the magnitude of change was small. EEG activity in the 13- to 30-Hz range significantly increased for all three midazolam infusion trials. Plots of midazolam plasma concentration versus pharmacodynamic EEG effect for the 1-hour and 3-hour infusion trials did not reveal evidence of either counterclockwise or clockwise hysteresis. Plots from the 1-minute infusion trial demonstrated counterclockwise hysteresis, consistent with an equilibration effect-site delay. This was incorporated into a kinetic-dynamic model in which hypothetical effect-site concentration was related to pharmacodynamic EEG effect via the sigmoid E(max) model. Analysis of all three infusion trials together yielded the following mean estimates: maximum EEG effect, 16.3% over baseline; 50% maximum effective concentration, 31 ng/mL; and an apparent rate constant for drug disappearance from the effect compartment which approached infinity. Despite the delay in effect onset during the 1-minute midazolam infusion, midazolam infusions in duration of up to 3 hours produce CNS sedation without evidence of tolerance.
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Affiliation(s)
- David J Greenblatt
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA
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Bareggi SR, Bianchi L, Cavallaro R, Gervasoni M, Siliprandi F, Bellodi L. Citalopram concentrations and response in obsessive-compulsive disorder. Preliminary results. CNS Drugs 2004; 18:329-35. [PMID: 15089116 DOI: 10.2165/00023210-200418050-00004] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
OBJECTIVE Citalopram, a highly potent SSRI, is effective in the treatment of depressive disorders and obsessive-compulsive disorder (OCD); however, very few studies have reported concentration-effect relationships for SSRIs. The aim of this study was to investigate the relationship between citalopram concentrations and clinical response in patients with OCD. METHODS AND STUDY DESIGN Fifteen patients (aged 18-65 years) with a DSM-IV diagnosis of OCD were included in this open-label, single-blind study. Citalopram was started at a dosage of 20 mg/day; the dosage was increased to a maximum of 60 mg/day by the third week, on the basis of clinical need and tolerability. The dosage then remained unchanged until the end of the 10-week study. Clinical assessments were made at baseline, weekly for the first four weeks and then at weeks 6, 8 and 10. The assessment scales used were the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), the Clinical Global Impression Scale (CGI) and the Hamilton Depression Rating Scale (HDRS). Plasma citalopram concentrations were determined using a high performance liquid chromatography method after solid phase extraction. RESULTS One patient was withdrawn from the study because of poor compliance. Of the 14 patients who completed the study, nine did not meet the treatment response criterion of an improvement of >25% from the baseline total Y-BOCS score and a score of < or =3 for the global improvement item of the CGI (these patients were termed non-responders), while five did (responders). There were no differences in the main demographic and baseline clinical variables between responders and non-responders. Steady-state citalopram concentrations were similar in the two groups, suggesting that the anti-obsessional effects of citalopram were not related to pharmacokinetic differences between responders and non-responders. There was no linear relationship between steady-state citalopram concentrations and response. The citalopram concentrations and Y-BOCS scores of individual responders obtained at baseline and various study timepoints showed a sigmoid relationship when analysed using the E(max) (maximum change in Y-BOCS score) model, with a mean EC(50) value (drug concentration that elicits 50% of the E(max)) of 152 microg/L, whereas a similar analysis of the non-responders generated a flat line. CONCLUSION The results of this preliminary study suggest that plasma citalopram concentrations may be related to the clinical response in responders, but do not seem to account for the lack of clinical effect in non-responders. These data, as well as the usefulness of the model in relating plasma concentrations to response, even after repeated administration, need to be validated by further investigations.
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Affiliation(s)
- Silvio R Bareggi
- Department of Pharmacology, University of Milan School of Medicine, Via Vanvitelli 32, I-20129 Milan, Italy.
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Cohen LM, Tessier EG, Germain MJ, Levy NB. Update on Psychotropic Medication Use in Renal Disease. PSYCHOSOMATICS 2004; 45:34-48. [PMID: 14709759 DOI: 10.1176/appi.psy.45.1.34] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Renal failure is a common medical condition, and many patients have comorbid psychiatric disorders. In this review, which is intended as a resource for consultation psychiatrists, the authors discuss pharmacokinetic considerations and provide information about the use of individual psychotropic medications in patients with renal disease. Most psychotropic medications are fat soluble, easily pass the blood-brain barrier, are not dialyzable, are metabolized primarily by the liver, and are excreted mainly in bile. Consequently, the majority of these drugs can be safely used with the end-stage renal disease population.
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Affiliation(s)
- Lewis M Cohen
- Psychiatri Consultation Service adn Renal Transplantation Service, Baystate Medical Center, Springfield, MA 01199, USA.
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Lucchesi LM, Pompéia S, Manzano GM, Kohn AF, Galduroz JCF, Bueno OFA, Tufik S. Flunitrazepam-induced changes in neurophysiological, behavioural, and subjective measures used to assess sedation. Prog Neuropsychopharmacol Biol Psychiatry 2003; 27:525-33. [PMID: 12691789 DOI: 10.1016/s0278-5846(03)00044-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
INTRODUCTION Certain features of event-related potentials (ERPs), electroencephalographic (EEG), and behavioural measures vary with differing states of alertness and/or sedation. PURPOSE This study was conducted to investigate changes in several measures usually viewed as reflecting states of sedation/sleepiness associated with the use of a range of doses of the hypnotic benzodiazepine (BZD) flunitrazepam (FNZ). METHODS This was a double blind, independent group design study of the effects of acute oral doses of FNZ in young healthy volunteers. Forty-eight subjects were randomly allocated to one of four groups-FNZ (0.6, 0.8, and 1.0 mg) and placebo (PLAC)-and tested prior to treatment and then in a posttreatment session close to the theoretical peak plasma concentration. ERP latencies and amplitudes were measured at midfrontal (Fz), midcentral (Cz), and midparietal (Pz) using a standard auditory oddball paradigm. EEG changes were assessed at Pz. Behavioural measures included the digit-symbol substitution test (DSST), a cancellation task (CT), and subjective ratings of alertness and attentiveness by the subjects (SUB) and the experimenter (EXP). RESULTS FNZ led to psychomotor impairments and decreased alertness and attention; these effects were consistent with previous findings. A progressive, dose-related increase in P3 latency occurred in Fz, Cz, and Pz, and there was an increase in N1 (Fz, Cz) and N2 (Fz). N2-P3 amplitude decreased in Fz. EEG power bands beta 1 increased for the two highest doses, but no significant differences were noted in theta, delta, and alpha bands. P3 latencies, experimenter-rated levels of alertness, and DSST scores differentiated all three doses of FNZ from PLAC. CONCLUSION The most sensitive measures used were P3 latencies of the ERPs (which varied with FNZ dose), DSST, and the experimenter-rated levels of alertness. However, we found no evidence for the assumption that one single phenomenon was reflected in all measures and different mechanisms were probably involved. Further experiments will be needed for more in-depth probing of the finer mechanisms underlying sedation/sleepiness and how they affect behavioural and eletrophysiological measures of the central nervous system (CNS) function.
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Affiliation(s)
- Lígia M Lucchesi
- Department of Psychobiology, Universidade Federal de São Paulo, R. Napoleão de Barros, 925 V. Clementino, CEP: 04024-002, São Paulo, SP, Brazil.
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Wolf DL, Desjardins PJ, Black PM, Francom SR, Mohanlal RW, Fleishaker JC. Anticipatory anxiety in moderately to highly-anxious oral surgery patients as a screening model for anxiolytics: evaluation of alprazolam. J Clin Psychopharmacol 2003; 23:51-7. [PMID: 12544376 DOI: 10.1097/00004714-200302000-00009] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Alprazolam, a benzodiazepine anxiolytic, was evaluated in anxious patients prior to oral surgery. This population represents a possible acute screening model for novel anxiolytic agents. Healthy subjects, preselected for a moderate to high degree of dental anxiety based upon Corah's Dental Anxiety Scale, were enrolled in a three-arm parallel design study and randomly assigned to receive double-blind placebo (N=15), alprazolam 0.25 mg (N=16) or alprazolam 1 mg (N=16). Subjective self-reported anxiety was rated using the State Anxiety Inventory and visual analog scales. Objective measures included galvanic skin conductance, heart rate variability, blood pressure, pulse rate, and respiration. At 90 minutes after dosing, there were statistically significant (p<0.05) reductions compared with placebo in subjective anxiety and skin conductance mean level for the alprazolam-treated subjects. Changes from pre-dose (mean +/- SEM) at 90 minutes in the placebo, alprazolam 0.25 mg, and alprazolam 1 mg groups were -4.73 +/- 2.79, -13.75 +/- 2.49, and -12.81 +/- 2.32 for the State Anxiety Inventory and 5.44 +/- 6.71, -31.88 +/- 5.88, and -32.34 +/- 5.32 mm for analog anxiety scores. Corresponding skin conductance mean level at 100 minutes in the three groups (respectively) changed 0.64 +/- 0.24, -0.53 +/- 0.21, -0.71 +/- 0.22 microSiemens. The 0.25 mg and 1 mg dosages of alprazolam were not differentiated. Changes in heart rate variability, blood pressure, pulse rate, and respiration did not reflect subjective anxiety. Overall, the oral surgery anticipation anxiety model was found to be a sensitive test for benzodiazepine anxiolytic activity and may represent a potential screening model for evaluation of investigational agents.
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Affiliation(s)
- Daniel L Wolf
- Clinical Pharmacology, Pharmacia Corporation, Kalamazoo, Michigan 49001, USA
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Visser SAG, Wolters FLC, Gubbens-Stibbe JM, Tukker E, Van Der Graaf PH, Peletier LA, Danhof M. Mechanism-based pharmacokinetic/pharmacodynamic modeling of the electroencephalogram effects of GABAA receptor modulators: in vitro-in vivo correlations. J Pharmacol Exp Ther 2003; 304:88-101. [PMID: 12490579 DOI: 10.1124/jpet.102.042341] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A mechanism-based pharmacokinetic-pharmacodynamic (PK/PD) model for neuroactive steroids, comprising a separate characterization of 1) the receptor activation process and 2) the stimulus-response relationship, was applied to various nonsteroidal GABAA receptor modulators. The EEG effects of nine prototypical GABAA receptor modulators (six benzodiazepines, one imidazopyridine, one cyclopyrrolone, and one beta-carboline) were determined in rats in conjunction with plasma concentrations. Population PK/PD modeling revealed monophasic concentration-EEG effect relationships with large differences in potency (EC50) and intrinsic activity between the compounds. The data were analyzed on the basis of the mechanism-based PK/PD model for (synthetic) neuroactive steroids on the assumption of a single and unique stimulus-response relationship. The model converged yielding estimates of both the apparent in vivo receptor affinity (KPD) and the in vivo intrinsic efficacy (ePD). The values of KPD ranged from 0.41 +/- 0 ng.ml(-1) for bretazenil to 436 +/- 72 ng.ml(-1) for clobazam and the values for e(PD) from -0.27 +/- 0 for methyl 6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate to 0.54 +/- 0.02 for diazepam. Significant linear correlations were observed between KPD for unbound concentrations and the affinity in an in vitro receptor bioassay (r = 0.93) and between e(PD) and the GABA-shift in vitro (r = 0.95). The findings of this investigation show that the in vivo effects of nonsteroidal GABAA receptor modulators and (synthetic) neuroactive steroids can be described on the basis of a single unique transducer function. In this paradigm, the nonsteroidal GABAA receptor modulators behave as partial agonists relative to neuroactive steroids.
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Affiliation(s)
- S A G Visser
- Division of Pharmacology, Leiden/Amsterdam Center for Drug Research, Leiden University, Leiden, The Netherlands
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Bauer LO, Hesselbrock VM. Lateral Asymmetries in the Frontal Brain: Effects of Depression and a Family History of Alcoholism in Female Adolescents. Alcohol Clin Exp Res 2002. [DOI: 10.1111/j.1530-0277.2002.tb02468.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Kotegawa T, Laurijssens BE, Von Moltke LL, Cotreau MM, Perloff MD, Venkatakrishnan K, Warrington JS, Granda BW, Harmatz JS, Greenblatt DJ. In vitro, pharmacokinetic, and pharmacodynamic interactions of ketoconazole and midazolam in the rat. J Pharmacol Exp Ther 2002; 302:1228-37. [PMID: 12183684 DOI: 10.1124/jpet.102.035972] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Interactions of midazolam and ketoconazole were studied in vivo and in vitro in rats. Ketoconazole (total dose of 15 mg/kg intraperitoneally) reduced clearance of intravenous midazolam (5 mg/kg) from 79 to 55 ml/min/kg (p < 0.05) and clearance of intragastric midazolam (15 mg/kg) from 1051 to 237 ml/min/kg (p < 0.05), increasing absolute bioavailability from 0.11 to 0.36 (p < 0.05). Presystemic extraction occurred mainly across the liver as opposed to the gastrointestinal tract mucosa. Midazolam increased electroencephalographic (EEG) amplitude in the beta-frequency range. Ketoconazole shifted the concentration-EEG effect relationship rightward (increase in EC(50)), probably because ketoconazole is a neutral benzodiazepine receptor ligand. Ketoconazole competitively inhibited midazolam hydroxylation by rat liver and intestinal microsomes in vitro, with nanomolar K(i) values. At a total serum ketoconazole of 2 microg/ml (3.76 microM) in vivo, the predicted reduction in clearance of intragastric midazolam by ketoconazole (to 6% of control) was slightly greater than the observed reduction in vivo (to 15% of control). However, unbound serum ketoconazole greatly underpredicted the observed clearance reduction. Although the in vitro and in vivo characteristics of midazolam in rats incompletely parallel those in humans, the experimental model can be used to assess aspects of drug interactions having potential clinical importance.
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Affiliation(s)
- Tsutomu Kotegawa
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Tufts-New England Medical Center, 136 Harrison Avenue, Boston, MA 02111, USA
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Ohtani Y, Kotegawa T, Tsutsumi K, Morimoto T, Hirose Y, Nakano S. Effect of fluconazole on the pharmacokinetics and pharmacodynamics of oral and rectal bromazepam: an application of electroencephalography as the pharmacodynamic method. J Clin Pharmacol 2002; 42:183-91. [PMID: 11831541 DOI: 10.1177/00912700222011229] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Quantitative analysis of electroencephalography (EEG) is used increasingly to evaluate the pharmacodynamics of benzodiazepines. The present study aimed to apply the EEG method as well as more traditional approaches to an interaction study of bromazepam and fluconazole. Twelve healthy male volunteers participated in a randomized, double-blind, four-way crossover study. The subjects received single oral or rectal doses of bromazepam (3 mg) after 4-day pretreatment of oral fluconazole (100 mg daily) or its placebo. Plasma bromazepam concentrations were measured before and 0.5, 1, 2, 3, 4, 6, 12, 22, 46, and 70 hours after bromazepam administration. Pharmacodynamic effects of bromazepam were assessed using self-rated drowsiness, continuous number addition test, and EEG. Fluconazole caused no significant changes in pharmacokinetics and pharmacodynamics of oral or rectal bromazepam. Rectal administration significantly increased AUC (1.7-fold, p < 0.0001) and Cmax (1.6-fold, p < 0.0001) of bromazepam. These changes following rectal dose may be due to avoidance of degradation occurring in the gastrointestinal tract. Rectal bromazepam also increased the area under the effect curves assessed by EEG (p < 0.05) and subjective drowsiness (p < 0.05). EEG effects were closely correlated with mean plasma bromazepam concentrations (r = 0.92, p < 0.001 for placebo; r = 0.89, p < 0.0001 for fluconazole). Thus, the EEG method provided pharmacodynamic data that clearly reflected the pharmacokinetics of bromazepam.
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Affiliation(s)
- Yasukiyo Ohtani
- Department of Clinical Pharmacology and Therapeutics, Oita Medical University, Japan
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Laurijssens BE, Greenblatt DJ. Effect of 7-day exposure to midazolam on electroencephalogram pharmacodynamics in rats: a model to study multiple pharmacokinetic-pharmacodynamic relationships in individual animals. J Pharm Pharmacol 2002; 54:77-86. [PMID: 11829133 DOI: 10.1211/0022357021771959] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
The objective of this study was to determine the concentration-electroencephalogram (EEG) relationships for midazolam, a full-agonist benzodiazepine ligand, on multiple occasions in individual rats, and to examine the effect of chronic midazolam exposure on that relationship. Rats were chronically instrumented with venous and arterial cannulas, and cortical EEG electrodes. The rats received either: 7 days of midazolam 10 mg kg(-1) intravenously once a day (midazolam group); or midazolam on days 1 and 7 and vehicle on days 2-6 (vehicle group). Concentration-effect relationships were determined on days 1, 4 and 7 from multiple blood and EEG samples before and after the administration of the midazolam dose. The concentration-EEG effect relationships were consistent with a sigmoidal Emax (maximal effect) model. No differences in pharmacokinetic or pharmacodynamic parameters were found between day 1 and day 7 in either group. However, in the midazolam group, both the fraction unbound of midazolam in serum and the EC50 (concentration at half-maximal effect) for free midazolam increased from days 1-7 by 35 +/- 3% and 54 +/- 25%, respectively (means +/- s.d., P< 0.05). This may be related to decreased serum albumin levels in the midazolam group (-19+5%, P < 0.05) which, in turn, could be explained by the sedation associated with daily midazolam treatment. We concluded that concentration-EEG effect relationships can be studied on multiple occasions in individual animals, reducing animal use and variability. A modest degree of tolerance to midazolam was found with this paradigm, the effect only being evident after correction for the fraction unbound of midazolam.
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Affiliation(s)
- Bart E Laurijssens
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, MA 02111, USA
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Sun L, Lau CE. Arteriovenous serum cocaine concentration difference after intravenous bolus injection and constant-rate infusions: relation to pharmacodynamic estimates in rats. Eur J Pharm Sci 2001; 14:261-9. [PMID: 11684400 DOI: 10.1016/s0928-0987(01)00180-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We characterized the pharmacokinetics of cocaine using both arterial and venous serum data after a bolus dose (2 mg/kg) and two constant-rate infusions (12.24 and 24.48 microg/min) for 2 h in rats. A published behavioral effect was used to investigate the effects of arteriovenous serum concentration differences on pharmacodynamic estimates for the 2 mg/kg dose. Significant temporal arteriovenous serum cocaine and benzoylecgonine (the major metabolite) concentration differences existed after cocaine administrations. The AUCs for arterial serum data were greater than the AUCs for venous data, indicating that cocaine was metabolized more extensively in the venous sampling site. Cocaine's behavioral effect could be directly related to serum concentrations with no hysteresis observed between the effects and arterial or venous serum concentrations. The pharmacodynamic estimates derived from arterial serum data approximated those from the venous data due to the most decline of cocaine's effect occurred in the elimination phase during which serum cocaine concentrations were not significantly different between the two sampling sites.
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Affiliation(s)
- L Sun
- Department of Psychology, Rutgers, The State University of NJ, Piscataway, NJ, USA
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Venkatakrishnan K, Schmider J, Harmatz JS, Ehrenberg BL, von Moltke LL, Graf JA, Mertzanis P, Corbett KE, Rodriguez MC, Shader RI, Greenblatt DJ. Relative contribution of CYP3A to amitriptyline clearance in humans: in vitro and in vivo studies. J Clin Pharmacol 2001; 41:1043-54. [PMID: 11583471 DOI: 10.1177/00912700122012634] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The relative contribution of cytochrome P450 3A (CYP3A) to the oral clearance of amitriptyline in humans has been assessed using a combination of in vitro approaches together with a clinical pharmacokinetic interaction study using the CYP3A-selective inhibitor ketoconazole. Lymphoblast-expressed CYPs were used to study amitriptyline N-demethylation and E-10 hydroxylation in vitro. The relative activity factor (RAF) approach was used to predict the relative contribution of each CYP isoform to the net hepatic intrinsic clearance (sum of N-demethylation and E-10 hydroxylation). Assuming no extrahepatic metabolism, the model-predicted contribution of CYP3A to net intrinsic clearance should equal the fractional decrement in apparent oral clearance of amitriptyline upon complete inhibition of the enzyme. This hypothesis was tested in a clinical study of amitriptyline (50 mg, p.o.) with ketoconazole (three 200 mg doses spaced 12 hours apart) in 8 healthy volunteers. The RAF approach predicted CYP2C19 to be the dominant contributor (34%), with a mean 21% contribution of CYP3A (range: 8%-42% in a panel of 12 human livers). The mean apparent oral clearance of amitriptyline in 8 human volunteers was decreased from 2791 ml/min in the control condition to 2069 ml/min with ketoconazole. The average 21% decrement (range: 2%-40%) was identical to the mean value predicted in vitro using the RAF approach. The central nervous system (CNS) sedative effects of amitriptyline were slightly greater when ketoconazole was coadministered, but the differences were not statistically significant. In conclusion, CYP3A plays a relatively minor role in amitriptyline clearance in vivo, which is consistent with in vitro predictions using the RAF approach.
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Affiliation(s)
- K Venkatakrishnan
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine and New England Medical Center, Boston, MA 02111, USA
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de Wit H, Schmitt L, Purdy R, Hauger R. Effects of acute progesterone administration in healthy postmenopausal women and normally-cycling women. Psychoneuroendocrinology 2001; 26:697-710. [PMID: 11500251 DOI: 10.1016/s0306-4530(01)00024-5] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The goal of this study was to investigate the behavioral and subjective effects of single doses of progesterone (intramuscular) in post-menopausal women and in women with normal menstrual cycles. Although certain metabolites of progesterone (e.g., allopregnanolone) are known to bind to GABA(A) receptors and produce sedative-like effects in laboratory animals, few studies have examined the acute effects of these neurosteroids in humans. Postmenopausal women (N=10) received progesterone (25, 50, 100 mg im) or placebo at weekly intervals, and women with normal menstrual cycles (N=8) received progesterone (100 mg im) or placebo once a month during the early follicular phase. Dependent measures included plasma levels of progesterone and allopregnanolone, self-report measures of mood and subjective effects and psychomotor performance. Plasma concentrations of progesterone and allopregnanolone increased in a time and dose-dependent manner, with relatively little variability. The concentrations were similar in both groups, although the ratio of allopregnanolone to progesterone was higher in cycling women at certain time points. Contrary to expectations, progesterone produced only modest behavioral or subjective effects. In the cycling women, it produced mild sedative-like effects (i.e., decreases in ratings of Vigor and Friendliness). In the post-menopausal women, only the highest dose (100 mg) slightly increased ratings of feeling "sluggish". These results suggest that progesterone and its metabolites, at concentrations well beyond those attained during the normal menstrual cycle, produce only marginal sedative-like effects. These findings suggest that brief (i.e., several hours) increases in plasma levels of allopregnanolone do not have direct effects on mood.
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Affiliation(s)
- H de Wit
- Department of Psychiatry, The University of Chicago, 5841 S. Maryland Avenue, Chicago, IL 60637, USA.
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Blin O, Simon N, Jouve E, Habib M, Gayraud D, Durand A, Bruguerolle B, Pisano P. Pharmacokinetic and pharmacodynamic analysis of sedative and amnesic effects of lorazepam in healthy volunteers. Clin Neuropharmacol 2001; 24:71-81. [PMID: 11307041 DOI: 10.1097/00002826-200103000-00002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This study describes for the first time the pharmacokinetic and pharmacodynamic modeling of the psychomotor and amnesic effects of a single 2-mg oral dose of lorazepam in healthy volunteers. Twelve healthy volunteers were included in this randomized, double-blinded, placebo-controlled two-way crossover study. The effect of lorazepam was examined for a battery of tests that explored mood, vigilance, psychomotor performance, and memory. The pharmacokinetic and pharmacodynamic modeling of these tests was performed using the indirect response model. Vigilance and psychomotor performance were significantly impaired. Short-term memory was not affected, but a paradoxical tendency to improvement of the score was observed 0.4 hours after drug intake. Significant impairment was observed for immediate and delayed cued verbal recall, for immediate and delayed free recall, and for picture recognition as well as for visual-verbal recall, but not for cued visual-spatial recall or priming. Globally, the different effects were greatest between 0.4 to 3 hours after dosing. However, the time course profile of the recovery period suggests a possible dissociation between the kinetics of the effects of lorazepam on vigilance, psychomotor performance, and visual episodic memory, on the one hand, and on verbal episodic memory, on the other. The pharmacokinetic and pharmacodynamic model used two compartments with first-order absorption to describe the lorazepam concentrations and an indirect response model with inhibition or stimulation of Kin to describe the effects. The mean values for calculated median effective concentration (EC50) derived from the pharmacokinetic and pharmacodynamic modeling of the different tests ranged from 11.3 to 39.8 ng/mL. According to these EC50 values, lorazepam seemed to be more potent on the delayed-recall trials than on the immediate-recall trials; similar observations were made concerning the free-recall versus cued-recall trials. The previously stated results suggest that the tests performed in this study represent sensitive measurements of the effects of lorazepam on the central nervous system. Moreover, the parameter values derived from pharmacokinetic and pharmacodynamic modeling, especially, the EC50 values, may provide sensitive indices that can be used to compare the central nervous system effects of benzodiazepines.
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Affiliation(s)
- O Blin
- Fédération de Pharmacologie Médicale et Clinique et Pharmacocinétique, CHU Timone, Marseille, France
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Greenblatt DJ, von Moltke LL, Ehrenberg BL, Harmatz JS, Corbett KE, Wallace DW, Shader RI. Kinetics and dynamics of lorazepam during and after continuous intravenous infusion. Crit Care Med 2000; 28:2750-7. [PMID: 10966246 DOI: 10.1097/00003246-200008000-00011] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To evaluate the kinetics and dynamics of lorazepam during administration as a bolus plus an infusion, using electroencephalography as a pharmacodynamic end point. METHODS Nine volunteers received a 2-mg bolus loading dose of lorazepam, coincident with the start of a 2 microg/kg/hr zero-order infusion. The infusion was stopped after 4 hrs. Plasma lorazepam concentrations and electroencephalographic activity in the 13- to 30-Hz range were monitored for 24 hrs. RESULTS The bolus-plus-infusion scheme rapidly produced plasma lorazepam concentrations that were close to those predicted to be achieved at true steady state. Mean kinetic values for lorazepam were as follows: volume of distribution, 126 L; elimination half-life, 13.8 hrs; and clearance, 109 mL/min. Electroencephalographic effects were maximal 0.5 hr after the loading dose, were maintained essentially constant during infusion, and then declined in parallel with plasma concentrations after the infusion was terminated. There was no evidence of tolerance. Plots of pharmacodynamic electroencephalographic effect vs. plasma lorazepam concentration demonstrated counterclockwise hysteresis, consistent with an effect-site equilibration delay. This was incorporated into a kinetic-dynamic model in which hypothetical effect-site concentration was related to pharmacodynamic electroencephalographic effect via the sigmoid Emax model. The analysis yielded the following mean estimates: maximum electroencephalographic effect, 12.7% over baseline; 50% effective concentration, 13.1 ng/mL; and effect-site equilibration half-life, 8.8 mins. CONCLUSION Despite the delay in effect onset, continuous infusion of lorazepam, preceded by a bolus loading dose, produces a relatively constant sedative effect on the central nervous system, which can be utilized in the context of critical care medicine.
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Affiliation(s)
- D J Greenblatt
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, MA 02111, USA.
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Kaplan GB, Greenblatt DJ, Ehrenberg BL, Goddard JE, Harmatz JS, Shader RI. Differences in pharmacodynamics but not pharmacokinetics between subjects with panic disorder and healthy subjects after treatment with a single dose of alprazolam. J Clin Psychopharmacol 2000; 20:338-46. [PMID: 10831021 DOI: 10.1097/00004714-200006000-00008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The pharmacokinetics and pharmacodynamics of the benzodiazepine alprazolam (1 mg, administered orally) were compared between eight patients with panic disorder and eight age- and sex-matched healthy volunteers. Subjects received orally administered placebo and alprazolam in a randomized, double-blind, single-dose crossover study. The elimination half-life, time of maximum plasma concentration, maximum concentration, volume of distribution, and clearance of alprazolam were similar for both groups. For each cohort, alprazolam treatment (vs. placebo) produced significant changes in typical benzodiazepine agonist effects, such as increased sedation and impaired cognitive performance on the digit-symbol substitution test. For the panic disorder group only, there was a significant increase in the subjective rating of"contented" and a reduction in the rating of "easily irritated." For the healthy volunteer group, alprazolam produced increases in ratings of "fatigued" and "slowed thinking," but also increases in ratings of "relaxed." In each group, alprazolam significantly increased the electroencephalographic (EEG) measure of relative beta amplitude (range, 13-30 Hz) compared with placebo. Concentration-EEG response curves fit a sigmoid E(max) model, and there was greater sensitivity to EEG effects, as measured by a 28% reduction in the EC50 value, in the panic disorder group compared with healthy control subjects. After alprazolam treatment, there was increased sensitivity to EEG and mood effects and fewer aversive effects in the panic disorder group compared with healthy subjects. There were no differences in the pharmacodynamic measures of sedation and cognition or differences in pharmacokinetics between the two groups.
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Affiliation(s)
- G B Kaplan
- Veterans Affairs Medical Center and the Department of Psychiatry and Human Behavior, Brown University School of Medicine, Providence, Rhode Island, USA
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Sleeper R, Bond CA, Rojas-Fernandez C. Psychotropic drugs and falls: new evidence pertaining to serotonin reuptake inhibitors. Pharmacotherapy 2000; 20:308-17. [PMID: 10730686 DOI: 10.1592/phco.20.4.308.34885] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Falls are a significant cause of fatal and nonfatal injuries in older persons. Risk factors include previous falls, several disease states, and certain drugs such as tricyclic antidepressants and antihypertensives. We conducted a MEDLINE search from January 1966-March 1999 to identify studies and review articles on the association of neuroleptics, benzodiazepines, and antidepressants with fall risk in older people. The focus was on the risk associated with serotonin reuptake inhibitors, biologic plausibility, and limitations of these studies. It was thought that the agents did not increase the risk of falls, although recent evidence suggests that this is not the case.
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Affiliation(s)
- R Sleeper
- Department of Pharmacy Practice, School of Pharmacy, Texas Tech University Health Sciences Center-Lubbock, USA
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Venkatakrishnan K, von Moltke LL, Greenblatt DJ. Effects of the antifungal agents on oxidative drug metabolism: clinical relevance. Clin Pharmacokinet 2000; 38:111-80. [PMID: 10709776 DOI: 10.2165/00003088-200038020-00002] [Citation(s) in RCA: 367] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
This article reviews the metabolic pharmacokinetic drug-drug interactions with the systemic antifungal agents: the azoles ketoconazole, miconazole, itraconazole and fluconazole, the allylamine terbinafine and the sulfonamide sulfamethoxazole. The majority of these interactions are metabolic and are caused by inhibition of cytochrome P450 (CYP)-mediated hepatic and/or small intestinal metabolism of coadministered drugs. Human liver microsomal studies in vitro, clinical case reports and controlled pharmacokinetic interaction studies in patients or healthy volunteers are reviewed. A brief overview of the CYP system and the contrasting effects of the antifungal agents on the different human drug-metabolising CYP isoforms is followed by discussion of the role of P-glycoprotein in presystemic extraction and the modulation of its function by the antifungal agents. Methods used for in vitro drug interaction studies and in vitro-in vivo scaling are then discussed, with specific emphasis on the azole antifungals. Ketoconazole and itraconazole are potent inhibitors of the major drug-metabolising CYP isoform in humans, CYP3A4. Coadministration of these drugs with CYP3A substrates such as cyclosporin, tacrolimus, alprazolam, triazolam, midazolam, nifedipine, felodipine, simvastatin, lovastatin, vincristine, terfenadine or astemizole can result in clinically significant drug interactions, some of which can be life-threatening. The interactions of ketoconazole with cyclosporin and tacrolimus have been applied for therapeutic purposes to allow a lower dosage and cost of the immunosuppressant and a reduced risk of fungal infections. The potency of fluconazole as a CYP3A4 inhibitor is much lower. Thus, clinical interactions of CYP3A substrates with this azole derivative are of lesser magnitude, and are generally observed only with fluconazole dosages of > or =200 mg/day. Fluconazole, miconazole and sulfamethoxazole are potent inhibitors of CYP2C9. Coadministration of phenytoin, warfarin, sulfamethoxazole and losartan with fluconazole results in clinically significant drug interactions. Fluconazole is a potent inhibitor of CYP2C19 in vitro, although the clinical significance of this has not been investigated. No clinically significant drug interactions have been predicted or documented between the azoles and drugs that are primarily metabolised by CYP1A2, 2D6 or 2E1. Terbinafine is a potent inhibitor of CYP2D6 and may cause clinically significant interactions with coadministered substrates of this isoform, such as nortriptyline, desipramine, perphenazine, metoprolol, encainide and propafenone. On the basis of the existing in vitro and in vivo data, drug interactions of terbinafine with substrates of other CYP isoforms are unlikely.
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Affiliation(s)
- K Venkatakrishnan
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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Sarid‐Segal O, Knapp CM, Ciraulo AM, Greenblatt DJ, Shader RI, Ciraulo DA. Decreased EEG Sensitivity to Alprazolam in Subjects with a Parental History of Alcoholism. J Clin Pharmacol 2000. [DOI: 10.1177/009127000004000111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Ofra Sarid‐Segal
- Division of Psychiatry, Boston University School of Medicine and the VA Boston Health Care System, Boston, Massachusetts
| | - Clifford M. Knapp
- Division of Psychiatry, Boston University School of Medicine and the VA Boston Health Care System, Boston, Massachusetts
| | - Ann Marie Ciraulo
- Division of Psychiatry, Boston University School of Medicine and the VA Boston Health Care System, Boston, Massachusetts
| | - David J. Greenblatt
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, Massachusetts
| | - Richard I. Shader
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, Massachusetts
| | - Domenic A. Ciraulo
- Division of Psychiatry, Boston University School of Medicine and the VA Boston Health Care System, Boston, Massachusetts
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Lau CE, Wang Y, Sun L, Lobarinas E, Wang Q, Nguyen KN, Falk JL. Pharmacokinetic determinants of cocaine's differential effects on locomotor and operant behavior. Eur J Pharmacol 1999; 381:85-92. [PMID: 10554874 DOI: 10.1016/s0014-2999(99)00571-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Dose-response, effect-time and concentration-effect relations of intravenous cocaine (1-4 mg/kg) were investigated on contingency-controlled [fixed-ratio (FR) 70 performance] and unconditioned (locomotor activity) behaviors. Cocaine dose-response curves exhibited decreasing rates of response under the FR 70 schedule but increasing locomotor activity in a dose-related fashion. Effect-time profiles confirmed that these changes were time-dependent and provided additional clarity by mirroring the biexponential decay of cocaine concentrations with time. The duration of action of cocaine was comparatively shorter on locomotor activity than on FR performance. We integrated effect-time profiles of the two behaviors with concentration-time profiles simulated from our previously published pharmacokinetic parameters to derive cocaine's pharmacodynamic parameters. Classical inhibitory Emax and sigmoidal Emax models were used to describe cocaine's effects on FR performance and locomotor activity, respectively. Simultaneous pharmacokinetic-pharmacodynamic modeling reveals evidence of acute tolerance to cocaine in locomotor activity, as indicated by decreasing potency with dose, but not in contingency-controlled behavior.
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Affiliation(s)
- C E Lau
- Department of Psychology, Rutgers, The State University of New Jersey, New Brunswick 08854-0820, USA.
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Hanlon JT, Horner RD, Schmader KE, Fillenbaum GG, Lewis IK, Wall WE, Landerman LR, Pieper CF, Blazer DG, Cohen HJ. Benzodiazepine use and cognitive function among community-dwelling elderly. Clin Pharmacol Ther 1998; 64:684-92. [PMID: 9871433 DOI: 10.1016/s0009-9236(98)90059-5] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To evaluate the relation between benzodiazepine use and cognitive function among community-dwelling elderly. METHODS This prospective cohort study included 2765 self-reporting subjects from the Duke Established Populations for Epidemiologic Studies of the Elderly. The subjects were cognitively intact at baseline (1986-1987) and alive at follow-up data collection 3 years later. Cognitive function was assessed with the Short Portable Mental Status Questionnaire (unimpaired versus impaired and change in score) and on the basis of the number of errors on the individual domains of the Orientation-Memory-Concentration Test. Benzodiazepine use was determined during in-home interviews and classified by dose, half-life, and duration. Covariates included demographic characteristics, health status, and health behaviors. RESULTS After control for covariates, current users of benzodiazepine made more errors on the memory test (beta coefficient, 0.35; 95% confidence interval [CI], 0.10 to 0.61) than nonusers. Further assessment of the negative effects on memory among current users suggested a dose response in which users taking the recommended or higher dose made more errors (beta coefficient, 0.57; 95% CI, 0.26 to 0.88) and a duration response in which long-term users made more errors (beta coefficient, 0.39; 95% CI, 0.05 to 0.73) than nonusers. Users of agents with long half-lives and users of agents with short half-lives both had increased memory impairment (beta coefficient, 0.32; 95% CI, 0.01 to 0.64 and beta coefficient, 0.38; 95% CI, 0.02 to 0.75, respectively) relative to nonusers. Previous benzodiazepine use was unrelated to memory problems, and current and previous benzodiazepine use was unrelated to level of cognitive functioning as measured with the other 4 tests. CONCLUSIONS The results suggested that current benzodiazepine use, especially in recommended or higher doses, is associated with worse memory among community-dwelling elderly.
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Affiliation(s)
- J T Hanlon
- Department of Medicine, Duke University Medical Center, USA
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Greenblatt DJ, Harmatz JS, von Moltke LL, Ehrenberg BL, Harrel L, Corbett K, Counihan M, Graf JA, Darwish M, Mertzanis P, Martin PT, Cevallos WH, Shader RI. Comparative kinetics and dynamics of zaleplon, zolpidem, and placebo. Clin Pharmacol Ther 1998; 64:553-61. [PMID: 9834048 DOI: 10.1016/s0009-9236(98)90139-4] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
PURPOSE This study evaluated the relationship of dose, plasma concentration, and time to the pharmacodynamics of zaleplon and zolpidem, 2 structurally distinct benzodiazepine receptor agonists. METHOD Ten healthy male volunteers received single oral doses of placebo, 10 mg zaleplon, 20 mg zaleplon, 10 mg zolpidem, and 20 mg zolpidem in a double-blind, 5-condition crossover study, with 48 hours elapsing between trials. Plasma drug concentrations and pharmacodynamic effects were measured during the 8 to 24 hours after administration. RESULTS Kinetics of zaleplon and zolpidem were not significantly related to dose. However, zaleplon had more rapid elimination (apparent elimination half-life [t1/2] of 1 hour) and higher apparent oral clearance (approximately 4300 mL/min) than zolpidem (t1/2, 2.0 to 2.2 hours; apparent oral clearance, 340 to 380 mL/min). Active treatments produced pharmacodynamic effects consistent with benzodiazepine agonist activity: self- and observer-rated sedation, impairment of digit symbol substitution test (DSST) performance, impaired memory, and increased electroencephalographic activity in the beta frequency range. The overall order of agonist potency was as follows: placebo < 10 mg zaleplon < 20 mg zaleplon < 10 mg zolpidem < 20 mg zolpidem; on a number of measures, 20 mg zaleplon was comparable to 10 mg zolpidem. Quantitative effects of zolpidem 20 mg far exceeded those of other treatments. Dynamic effects of both drugs were significantly related to plasma concentration. CONCLUSIONS Benzodiazepine agonist effects of zaleplon and zolpidem were dose and concentration dependent. At the usual clinically effective hypnotic dose (10 mg of either drug), agonist effects of zolpidem exceeded those of zaleplon.
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Affiliation(s)
- D J Greenblatt
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, New England Medical Center Hospital, Boston 02111, USA.
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Bourin M, Colombel MC, Guitton B. Alprazolam 0.125 mg twice a day improves aspects of psychometric performance in healthy volunteers. J Clin Psychopharmacol 1998; 18:364-72. [PMID: 9790153 DOI: 10.1097/00004714-199810000-00003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The effects of alprazolam (0.125 mg) taken twice a day on several cognitive and performance tasks (Pictures test, Digit-Symbol Substitution Test, Choice Reaction Time [CRT], Critical Flicker Fusion [CFF]) were investigated in healthy students. A double-blind, independent group design was used to compare placebo with alprazolam (32 volunteers in each group). After random assignment, all subjects received placebo for 3 days (D) followed by 14 days of treatment with either alprazolam or placebo. Subjects completed a battery of tests at D0, D3, D7, D10, and D14. D3 performance was poorer in the alprazolam group except for CFF values (ascending values and total values), and the only significant improvement was in total reaction time on the CRT test. However, a significant improvement in performance (except in recognition reaction time) was shown at D7, D10, and D14 in the alprazolam group compared with the control group results. This study shows that repeated low doses of alprazolam produce small improvements in some aspects of psychomotor and cognitive functions. Training effect, tolerance effect, anxiolytic effect, and changes in receptor function and/or number are discussed to explain the performance improvement.
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Affiliation(s)
- M Bourin
- Department of Pharmacology and GIS Médicament, Faculty of Medicine, Nantes, France
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Greenblatt DJ, von Moltke LL, Harmatz JS, Counihan M, Graf JA, Durol AL, Mertzanis P, Duan SX, Wright CE, Shader RI. Inhibition of triazolam clearance by macrolide antimicrobial agents: in vitro correlates and dynamic consequences. Clin Pharmacol Ther 1998; 64:278-85. [PMID: 9757151 DOI: 10.1016/s0009-9236(98)90176-x] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND Macrolide antimicrobial agents may impair hepatic clearance of drugs metabolized by cytochrome P4503A isoforms. Potential interactions of triazolam, a substrate metabolized almost entirely by cytochrome P4503A in humans, with 3 commonly prescribed macrolides were identified using an in vitro metabolic model. The actual interactions, and their pharmacodynamic consequences, were verified in a controlled clinical study. METHODS In an in vitro model using human liver microsomes, 250 mumol/L triazolam was incubated with ascending concentrations (0 to 250 mumol/L of troleandomycin, azithromycin, erythromycin, and clarithromycin. In a randomized, double-blind, 5-trial clinical pharmacokinetic-pharmacodynamic study, 12 volunteers received 0.125 mg triazolam orally, together with placebo, azithromycin, erythromycin, or clarithromycin. In a fifth trial they received placebo plus placebo. RESULTS Mean 50% inhibitory concentrations versus 4-hydroxytriazolam formation in vitro were as follows: 3.3 mumol/L troleandomycin, 27.3 mumol/L erythromycin, 25.2 mumol/L clarithromycin, and greater than 250 mumol/L azithromycin. Apparent oral clearance of triazolam when given with placebo or azithromycin was nearly identical (413 and 416 mL/min), as were peak plasma concentrations (1.25 and 1.32 ng/mL) and elimination half-life (2.7 and 2.6 hours). Apparent oral clearance was significantly reduced (P < .05) during erythromycin and clarithromycin trials (146 and 95 mL/min). Peak plasma concentration was correspondingly increased, and elimination half-life was prolonged. The effects of triazolam on dynamic measures were nearly identical when triazolam was given with placebo or azithromycin, but benzodiazepine agonist effects were enhanced during erythromycin and clarithromycin trials. CONCLUSION The in vitro model identifies macrolides that may impair triazolam clearance. Anticipated interactions, and their pharmacodynamic consequences in volunteer subjects, were verified in vivo.
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Affiliation(s)
- D J Greenblatt
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, MA 02111, USA
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Greenblatt DJ, Wright CE, von Moltke LL, Harmatz JS, Ehrenberg BL, Harrel LM, Corbett K, Counihan M, Tobias S, Shader RI. Ketoconazole inhibition of triazolam and alprazolam clearance: differential kinetic and dynamic consequences. Clin Pharmacol Ther 1998; 64:237-47. [PMID: 9757147 DOI: 10.1016/s0009-9236(98)90172-2] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Kinetic and dynamic consequences of metabolic inhibition were evaluated in a study of the interaction of ketoconazole, a P4503A inhibitor, with alprazolam and triazolam, two 3A substrate drugs with different kinetic profiles. METHODS In a double-blind, 5-way crossover study, healthy volunteers received (A) ketoconazole placebo plus 1.0 mg alprazolam orally, (B) 200 mg ketoconazole twice a day plus 1.0 mg alprazolam, (C) ketoconazole placebo plus 0.25 mg triazolam orally, (D) 200 mg ketoconazole twice a day plus 0.25 mg triazolam, and (E) 200 mg ketoconazole twice a day plus benzodiazepine placebo. Plasma concentrations and pharmacodynamic parameters were measured after each dose. RESULTS For trial B versus trial A, alprazolam clearance was reduced (27 versus 86 mL/min; P < .002) and apparent elimination half-life (t1/2) prolonged (59 versus 15 hours; P < .03), whereas peak plasma concentration (Cmax) was only slightly increased (16.1 versus 14.7 ng/mL). The 8-hour pharmacodynamic effect areas for electroencephalographic (EEG) beta activity were increased by a factor of 1.35, and those for digit-symbol substitution test (DSST) decrement were increased by 2.29 for trial B versus trial A. For trial D versus trial C, triazolam clearance was reduced (40 versus 444 mL/min; P < .002), t1/2 was prolonged (18.3 versus 3.0 hours; P < .01), and Cmax was increased (2.6 versus 5.4 ng/mL; P < .001). The 8-hour effect area for EEG was increased by a factor of 2.51, and that for DSST decrement was increased by 4.33. Observed in vivo clearance decrements due to ketoconazole were consistent with those anticipated on the basis of an in vitro model, together with in vivo plasma concentrations of ketoconazole. CONCLUSION For triazolam, an intermediate-extraction compound, impaired clearance by ketoconazole has more profound clinical consequences than those for alprazolam, a low extraction compound.
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Affiliation(s)
- D J Greenblatt
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, MA 02111, USA.
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