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Abstract
For a number of antidepressants in current clinical use, concentrations in serum or plasma are a more reliable index of target drug concentrations than is dosage. For such drugs, therapeutic drug monitoring (TDM) may be a useful clinical guide for the purpose of maximizing the likelihood of favorable therapeutic outcome while minimizing the probability of clinical ineffectiveness or adverse side effects. TDM is of greatest benefit when a therapeutic range of serum concentrations has been well established. Even if such a range is not definitively determined, TDM can be of help in situations in which patients are refractory to therapy despite adequate or high dosages, when adverse events supervene even with low doses, or when noncompliance with the intended dosage plan is suspected. Serum antidepressant concentrations from TDM should be interpreted in the full context of the patient's demographic characteristics and clinical status, along with an understanding of the pharmacokinetics of the medication being taken, the timing of the sample in relation to the dosage regimen, and the specific laboratory assay procedure. TDM measurements may be costly, and the potential benefits of the information need to be weighed against the cost to the patient or to the health care system.
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Affiliation(s)
- Najla Fiaturi
- Program in Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, MA, USA
- Program in Pharmacology and Drug Development, Tufts University School of Medicine, Boston, MA, USA
| | - David J Greenblatt
- Program in Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, MA, USA.
- Program in Pharmacology and Drug Development, Tufts University School of Medicine, Boston, MA, USA.
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Mauri MC, Fiorentini A, Paletta S, Altamura AC. Pharmacokinetics of antidepressants in patients with hepatic impairment. Clin Pharmacokinet 2015; 53:1069-81. [PMID: 25248846 DOI: 10.1007/s40262-014-0187-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Appropriate use of antidepressant in patients with hepatic impairment requires careful consideration of how the hepatic illness may affect pharmacokinetics. This review aims to analyze pharmacokinetic profile, plasma level variations so as the metabolism of several antidepressants relating to their use in patients with an hepatic impairment. Due to the lack of data regarding hepatic impairment itself, the review is focused mainly on studies investigating pharmacokinetics in hepatic cirrhosis or alcohol-related conditions. More data on reduced hepatic metabolism can be extrapolated by drug studies conducted in elderly populations. Dose adjustment of antidepressants in these patients is important as most of these drugs are predominantly metabolized by the liver and many of them are associated with dose-dependent adverse reactions. As no surrogate parameter is available to predict hepatic metabolism of drugs, dose adjustment according to pharmacokinetic properties of the drugs is proposed. There is a need for a more balanced assessment of the benefits and risks associated with antidepressants use in patients with hepatic impairment, particularly considering pharmacokinetic profile of the drugs to ensure that patients, who would truly benefit from these agents, are not denied appropriate treatment. In conclusion, kinetic studies for centrally acting drugs including antidepressants with predominant hepatic metabolism should be carried out in patients with liver disease to allow precise dose recommendations for enhanced patient safety.
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Affiliation(s)
- Massimo Carlo Mauri
- Clinical Psychiatry, Clinical Neuropsychopharmacology Unit, IRCCS Ospedale Maggiore Policlinico, Via F. Sforza 35, 20122, Milan, Italy,
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Hussain SA, Alzubaidi FA, Hashem HO. Effects of Gingko biloba extract on tissue distribution of fluoxetine and venlafaxine in rats. JOURNAL OF COMPLEMENTARY MEDICINE RESEARCH 2015; 4:234-8. [PMID: 26401414 PMCID: PMC4579493 DOI: 10.5455/jice.20150628102732] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 06/22/2015] [Indexed: 11/03/2022]
Abstract
OBJECTIVE There are many concerns about the interactions of herbal products with conventional drugs, which are mostly used as multiple drug treatment approach. The present study was designed to evaluate the effect of long-term use of Ginkgo biloba extract (GK) on the absorption and tissue distribution of fluoxetine and venlafaxine. MATERIALS AND METHODS 46 Wistar rats are utilized and allocated into 8 groups; 2 groups administered the vehicle and saved as control; 4 groups are treated with 100 and 200 mg/kg of GK extract for 30 days; 2 groups are treated with 40 mg/kg verapamil for 10 days. The liver, kidney, and brain distribution of fluoxetine and venlafaxine were evaluated after single oral doses using high performance liquid chromatographic method. RESULTS 200 mg/kg GK increases fluoxetine concentrations in all studied organs, while GK 100 mg/kg increases venlafaxine levels in kidney tissue and not affected in the other two organs. CONCLUSION Thirty days treatment with GK (100 mg/kg) increases kidney availability of venlafaxine, while 200 mg GK dose increases fluoxetine availability in the liver, kidney, and brain tissues after single oral doses.
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Affiliation(s)
- Saad Abdulrahman Hussain
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Baghdad, Baghdad, Iraq
| | | | - Hayder Obayes Hashem
- Department of Clinical Laboratory Sciences, College of Pharmacy, University of Babylon, Babylon, Iraq
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Wójcikowski J, Haduch A, Daniel WA. Effect of antidepressant drugs on cytochrome P450 2C11 (CYP2C11) in rat liver. Pharmacol Rep 2013; 65:1247-55. [DOI: 10.1016/s1734-1140(13)71482-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 09/11/2013] [Indexed: 12/20/2022]
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Haduch A, Bromek E, Daniel WA. The effect of psychotropic drugs on cytochrome P450 2D (CYP2D) in rat brain. Eur J Pharmacol 2010; 651:51-8. [PMID: 21115002 DOI: 10.1016/j.ejphar.2010.10.077] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Revised: 10/06/2010] [Accepted: 10/29/2010] [Indexed: 10/18/2022]
Abstract
The aim of the study was to investigate the influence of selected antidepressants and neuroleptics on the protein level and activity of cytochrome P450 2D (CYP2D) in rat brain. The obtained results showed that imipramine, fluoxetine, nefazodone, thioridazine and perazine, added to brain microsomes of control rats, inhibited CYP2D activity to a lower extent (K(i)=255-485μM) than when added to liver microsomes (K(i)=1-45μM), which may result from their stronger affinity for liver CYP2D2 (K(i)=2.7 and 1.25μM for imipramine and fluoxetine, respectively) than for brain CYP2D4 (K(i)=25 and 10μM for imipramine and fluoxetine, respectively), as well as from their high non-specific binding in brain microsomes. Two-week treatment with fluoxetine evoked decreases in the level and activity of CYP2D in the striatum and the nucleus accumbens. In contrast, fluoxetine increased CYP2D expression in the cerebellum, while nefazodone considerably enhanced the activity (but not the protein level) of CYP2D in the truncus cerebri. Imipramine and mirtazapine (active in the liver) did not affect brain CYP2D. Chronic thioridazine decreased CYP2D activity in the substantia nigra and nucleus accumbens, but significantly increased that activity in the striatum and cerebellum. Clozapine significantly enhanced CYP2D activity in the truncus cerebri. In conclusion, psychotropics influence CYP2D in the brain, but their effect is different than in the liver and depends on the cerebral structure. The observed psychotropics-brain CYP2D interactions may be important for the metabolism of neurosteroids and monoaminergic neurotransmitters, and for the local biotransformation of drugs.
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Affiliation(s)
- Anna Haduch
- Polish Academy of Sciences, Institute of Pharmacology, Kraków, Poland
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Rajasekhar D, Kumar IJ, Venkateswarlu P. Rapid high-performance liquid chromatography-tandem mass spectrometry method for simultaneous measurement of venlafaxine andO-desmethylvenlafaxine in human plasma and its application in comparative bioavailability study. Biomed Chromatogr 2009; 23:1300-7. [DOI: 10.1002/bmc.1253] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Qu Y, Aluisio L, Lord B, Boggs J, Hoey K, Mazur C, Lovenberg T. Pharmacokinetics and pharmacodynamics of norfluoxetine in rats: Increasing extracellular serotonin level in the frontal cortex. Pharmacol Biochem Behav 2009; 92:469-73. [DOI: 10.1016/j.pbb.2009.01.023] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Revised: 01/12/2009] [Accepted: 01/16/2009] [Indexed: 10/21/2022]
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Wille SMR, Cooreman SG, Neels HM, Lambert WEE. Relevant Issues in the Monitoring and the Toxicology of Antidepressants. Crit Rev Clin Lab Sci 2008; 45:25-89. [DOI: 10.1080/10408360701713112] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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Goodnick PJ, Benitez A. Section Review Central & Peripheral Nervous Systems: New antidepressant agents: Recent pharmacological developments leading to improved efficacy. Expert Opin Investig Drugs 2008. [DOI: 10.1517/13543784.4.10.935] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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de Castro A, Ramírez Fernandez MDM, Laloup M, Samyn N, De Boeck G, Wood M, Maes V, López-Rivadulla M. High-throughput on-line solid-phase extraction–liquid chromatography–tandem mass spectrometry method for the simultaneous analysis of 14 antidepressants and their metabolites in plasma. J Chromatogr A 2007; 1160:3-12. [PMID: 17321530 DOI: 10.1016/j.chroma.2007.01.137] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2006] [Revised: 01/15/2007] [Accepted: 01/18/2007] [Indexed: 10/23/2022]
Abstract
A rapid, sensitive and fully automated on-line solid-phase extraction-liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) method was developed and validated for the direct analysis of 14 antidepressants and their metabolites in plasma. Integration of the sample extraction and LC separation into a single system permitted direct injection of the plasma without prior sample pre-treatment. The applied gradient ensured the elution of all the examined drugs within 14 min and produced chromatographic peaks of acceptable symmetry. The total process time was 20 min and only 50 microL of plasma was required. Selectivity of the method was achieved by a combination of retention time and two precursor-product ion transitions for the non-deuterated compounds. The use of SPE was demonstrated to be highly effective and led to significant decreases in the interferences present in the matrix. Extraction was found to be both reproducible and efficient with recoveries >99% for all the analytes. The method showed excellent intra-assay and inter-assay precision (relative standard deviation (RSD) and bias <20%) for quality control (QC) samples spiked at a concentration of 40, 200 and 800 microg/L and the r2>0.99 over the range investigated (10-1000 microg/L). Limits of quantification (LOQs) were estimated to be 10 microg/L. Furthermore, the processed samples were demonstrated to be stable for at least 48 h, except for clomipramine and norclomipramine, where a slight negative trend was observed, but did not compromise the quantification. The method was subsequently applied to authentic samples previously screened by a routine HPLC method with diode array detection (DAD).
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Affiliation(s)
- Ana de Castro
- Forensic Toxicology Service, Institute of Legal Medicine, University of Santiago de Compostela, Santiago de Compostela, Spain
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Yuan Y, Tsoi K, Hunt RH. Selective serotonin reuptake inhibitors and risk of upper GI bleeding: confusion or confounding? Am J Med 2006; 119:719-27. [PMID: 16945603 DOI: 10.1016/j.amjmed.2005.11.006] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2005] [Revised: 11/01/2005] [Accepted: 11/01/2005] [Indexed: 11/19/2022]
Abstract
BACKGROUND Selective serotonin reuptake inhibitors (SSRIs) represent a relatively new class of antidepressants. Several studies have reported bleeding disorders associated with the use of SSRIs, which are considered the result of a decrease in platelet serotonin leading to a defect in platelet aggregation. To what extent the use of SSRIs increases the risk of gastrointestinal bleeding is unclear. METHODS A comprehensive literature search for studies addressing SSRI use and upper gastrointestinal tract bleeding (UGIB) was conducted using Medline, EMBASE, and Cochrane databases with a recursive manual reference search up to May 2005. Any observational and interventional studies were systematically reviewed, and critical appraisal was conducted on available studies. RESULTS Published clinical evidence on the relationship between SSRI use and gastrointestinal bleeding is limited to observational studies without any clinical trials. Three cohort studies and one case-control study met inclusion criteria. These studies combined different affinity SSRIs in the class and had differing control groups with conflicting conclusions. Both a cohort study and a case-control study investigating the concurrent use of nonsteroidal anti-inflammatory drugs (NSAIDs) or low-dose aspirin found that combined use with an SSRI increased the risk of UGIB. CONCLUSIONS Only a few epidemiology studies have investigated the association between SSRIs and UGIB. They provide weak evidence to support the hypothesis of a link between SSRIs and UGIB at a population level. Available evidence shows that concurrent use of NSAIDs or aspirin with SSRIs greatly increases the risk of UGIB. The preventive strategy should be considered in those SSRI users at high risk, especially the elderly or those with a history of UGIB and taking nonselective NSAIDs or aspirin.
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Affiliation(s)
- Yuhong Yuan
- Division of Gastroenterology, Department of Medicine, Health Science Centre, McMaster University, Hamilton, Ontario, Canada
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Abstract
A series of antiepileptic drugs have been investigated in terms of their ability to treat mania (with later applications for the treatment of bipolar depression and prevention of relapses). These include divalproex, carbamazepine, oxcarbazepine, gabapentin, lamotrigine, levetiracetam, tiagabine, topiramate and zonisamide. Although these drugs are all antiepileptic in action, they bring about these effects by different mechanisms; in particular, their impact on GABA differs significantly. Perhaps for this reason, their impact on mania varies greatly, with double-blind significant results evident only for valproate, carbamazepine and oxcarbazepine. Only valproate and carbamazepine are approved by the US FDA for use in mania; oxcarbazepine has never been found significantly effective in large-scale studies. Of the other options, both gabapentin and topiramate failed in large-scale investigations; tiagabine failed in small sample reports. Although lamotrigine has been successful in the prevention of depression relapse in bipolar disorder, it has not been effective in treating mania. Finally, there are no findings of large scale double-blind studies on the use of levetiracetam and zonisamide. A review of the kinetics, side effects and complications of the antiepileptic drugs indicates that carbamazepine is useful, and has adverse event benefit over all other options. The potential of zonisamide awaits further testing.
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Affiliation(s)
- Paul J Goodnick
- Department of Psychiatry, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Carrier Clinic, PO Box 147, Belle Mead, NJ 08502, USA.
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Baumann P, Ulrich S, Eckermann G, Gerlach M, Kuss HJ, Laux G, Müller-Oerlinghausen B, Rao ML, Riederer P, Zernig G, Hiemke C. The AGNP-TDM Expert Group Consensus Guidelines: focus on therapeutic monitoring of antidepressants. DIALOGUES IN CLINICAL NEUROSCIENCE 2005. [PMID: 16156382 PMCID: PMC3181735 DOI: 10.31887/dcns.2005.7.3/pbaumann] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Therapeutic drug monitoring (TDM) of psychotropic drugs such as antidepressants has been widely introduced for optimization of pharmacotherapy in psychiatric patients. The interdisciplinary TDM group of the Arbeitsgemeinschaft für Neuropsychopharmakologie und Pharmakopsychiatrie (AGNP) has worked out consensus guidelines with the aim of providing psychiatrists and TDM laboratories with a tool to optimize the use of TDM. Five research-based levels of recommendation were defined with regard to routine monitoring of drug plasma concentrations: (i) strongly recommended; (ii) recommended; (iii) useful; (iv) probably useful; and (v) not recommended. In addition, a list of indications that justify the use of TDM is presented, eg, control of compliance, lack of clinical response or adverse effects at recommended doses, drug interactions, pharmacovigilance programs, presence of a genetic particularity concerning drug metabolism, and children, adolescents, and elderly patients. For some drugs, studies on therapeutic ranges are lacking, but target ranges for clinically relevant plasma concentrations are presented for most drugs, based on pharmacokinetic studies reported in the literature. For many antidepressants, a thorough analysis of the literature on studies dealing with the plasma concentration-clinical effectiveness relationship allowed inclusion of therapeutic ranges of plasma concentrations. In addition, recommendations are made with regard to the combination of pharmacogenetic (phenotyping or genotyping) tests with TDM. Finally, practical instructions are given for the laboratory practitioners and the treating physicians how to use TDM: preparation of TDM, drug analysis, reporting and interpretation of results, and adequate use of information for patient treatment TDM is a complex process that needs optimal interdisciplinary coordination of a procedure implicating patients, treating physicians, clinical pharmacologists, and clinical laboratory specialists. These consensus guidelines should be helpful for optimizing TDM of antidepressants.
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Affiliation(s)
- Pierre Baumann
- Department of Psychiatry, University of Lausanne, Prilly Lausanne, Switzerland.
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Abstract
For nearly 50 years, antidepressant drugs have been the first-line treatment for various forms of depression. Despite their widespread use, these medications have significant shortcomings, in particular problems of patient compliance due to adverse effects. The introduction of new formulations of existing antidepressant medications may provide patients with benefits in terms of convenience of use. As a consequence, improvements in compliance may lead to better antidepressant efficiency.An orally disintegrating formulation of mirtazapine (mirtazapine SolTab), a once-weekly formulation of fluoxetine, an enantiomer-specific formulation of citalopram (escitalopram), an extended-release formulation of venlafaxine (venlafaxine XR), a controlled-release formulation of paroxetine (paroxetine CR) and intravenous formulations of some of the newer antidepressants have all been evaluated in limited clinical trials. In this article, a review of the pharmacokinetics and clinical evaluations of these formulations is presented. While there do not appear to be major clinical advantages for the new formulations in terms of antidepressant efficacy, none of them is less efficacious than their older counterpart. Indeed, some of the new formulations are more acceptable to patients (fluoxetine once-weekly, paroxetine CR), others have pharmacokinetic advantages (venlafaxine XR, paroxetine CR), while others may have a faster onset of effect (mirtazapine SolTab, intravenous formulations). Further evaluation of some formulations is still required (mirtazapine SolTab, fluoxetine once-weekly), while others (venlafaxine XR, escitalopram) are finding widespread acceptance in clinical practice.
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Affiliation(s)
- Trevor R Norman
- Department of Psychiatry, University of Melbourne, Austin & Repatriation Medical Centre, Heidelberg, Victoria, Australia.
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Sorvaniemi M, Helenius H, Salokangas RKR. Factors associated with being granted a pension among psychiatric outpatients with major depression. J Affect Disord 2003; 75:43-8. [PMID: 12781349 DOI: 10.1016/s0165-0327(02)00034-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Little is known about factors associated with early retirement due to major depression in naturalistic settings. We examined to what extent major depression leads to disability pension and whether there are any associated factors with being granted a pension. METHODS In our retrospective document-based cohort study of 213 adult psychiatric outpatients with first-time documented DSM-III-R major depression, several sociodemographic, clinical and treatment characteristics were detected during the follow-up time of 3 months of medical care in Finland. This information was related to official registers of granted pensions with a follow-up time of 30 months. RESULTS Forty-six (21.6%) patients were granted a pension during the follow-up period. Greater age, comorbidity and lowered self-esteem were strongly associated with being granted a pension. DISCUSSION Some risk factors associated with subsequent retirement could be identified at the early phase of the illness.
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Affiliation(s)
- Marko Sorvaniemi
- Psychiatric Policlinic of Rauma, Satakunta Hospital District, Steniuksenkatu 2, 26100 Rauma, Finland.
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Abstract
Thirty-three members of the United Kingdom National External Quality Assessment Scheme for measurement of psychoactive drugs in serum responded to a questionnaire concerning 31 tricyclic, antipsychotic, and selective serotonin re-uptake inhibitor drugs. Considerable variation was found between laboratories in their reference ranges and in the observed range of measured drug concentrations in clinical samples. For the lower end of the reference range, the median ratio between the highest and lowest values reported was 6.8, while for the top end of the range, the median ratio was 3.6. Observed clinical values were significantly less than reference range values at the lower end of the range and significantly higher at upper-range values by median values of -57% and +47%, respectively. The median ratio between maximum and minimum measurements reported by laboratories was 10.0 for both the lowest non-zero measurements and the highest non-toxicological concentrations. The variation in clinical range values did not differ significantly from that in reference range values. The ratios take no account of local variation in patient groups and treatment regimens.
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Affiliation(s)
- John F Wilson
- Department of Pharmacology, Therapeutics & Toxicology, University of Wales College of Medicine, Heath Park, Cardiff.
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Abstract
This article reviews the risk factors, pathogenesis, treatment, and prevention of postpartum depression. Postpartum depression is common and occurs in up to 18% of newly delivered mothers. Though the hormonal changes occurring after childbirth are believed to play a role in postpartum depression, no hormonal etiology has been identified. Estrogen appears somewhat helpful for postpartum depression, but its use is limited by problematic medical sequelae. Several antidepressants are effective for postpartum depression and appear safe for use by breastfeeding women. Psychosocial interventions and cultural rituals, which may prevent or ameliorate postpartum depression, have also been employed.
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Affiliation(s)
- Deborah Lynne Flores
- Department of Psychiatry and Behavioral Sciences, University of California, Los Angeles, Neuropsychiatric Institute and Hospital, 760 Westwood Boulevard, Los Angeles, CA 90024, USA.
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Abstract
OBJECTIVE To determine whether bupropion overdose has been associated with cardiovascular toxicity. DATA SOURCES MEDLINE (1966-January 2002), EMBASE (1980-January 2002), Current Contents (January 2002), and PubMed (January 2002) databases for English-language human reports. Search terms included bupropion, overdose (drug), intoxication, poisoning, and acute ingestion. DATA SYNTHESIS Articles describing toxicity following bupropion overdose were evaluated independently by both authors to identify cases of cardiotoxicity. RESULTS Thirteen articles describing bupropion overdose in 116 patients were identified. Only 3 patients exhibited cardiotoxicity following acute ingestion; 2 of these patients also ingested other medications. All 3 patients experienced tachycardia and conduction delays (widened QRS complex and/or prolonged QTc interval), but none of these delays progressed to a life-threatening arrhythmia. All patients recovered, with resolution of cardiotoxicity within 2-4 days following ingestion. CONCLUSIONS We recommend that all patients with an overdose of bupropion should have an electrocardiogram performed on admission and should be monitored for the development of conduction delays and/or life-threatening arrhythmias.
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Affiliation(s)
- Deon Druteika
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
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Abstract
The benzamide moclobemide is a reversible inhibitor of monoamine-oxidase-A (RIMA). It has been extensively evaluated in the treatment of a wide spectrum of depressive disorders and less extensively in anxiety disorders. While clinical aspects will be presented in a subsequent review, this article focuses primarily on moclobemide's evolution, pharmacodynamic and pharmacokinetic properties. In particular, the effects on neurotransmission and intracellular signal transduction, the neuroendocrine system, the tyramine pressure response and animal models of depression are surveyed. In addition, other CNS effects are reviewed with special respect to experimental serotonergic syndrome, anxiolytic and antinociceptive activity, sleep, cognition and driving performance, neuroprotection and seizures.
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Affiliation(s)
- Udo Bonnet
- Rheinische Kliniken Essen, Department of Psychiatry and Psycotherapy, University of Essen, Essen, Germany.
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Matoga M, Pehourcq F, Titier K, Dumora F, Jarry C. Rapid high-performance liquid chromatographic measurement of venlafaxine and O-desmethylvenlafaxine in human plasma. Application to management of acute intoxications. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 2001; 760:213-8. [PMID: 11530979 DOI: 10.1016/s0378-4347(01)00270-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Venlafaxine, a second-generation antidepressant, acts by inhibition of the reuptake of presynaptic noradrenaline and serotonin. The main metabolite, O-desmethylvenlafaxine was found biologically active. For toxicological purpose, a rapid specific and accurate RP-HPLC assay was developed for the simultaneous determination of venlafaxine and O-desmethylvenlafaxine in human plasma. A linear response was observed over the concentration range 0.2-4 microg/ml. A good accuracy (<8%) was achieved for all quality controls, with intra-day and inter-day variation coefficient less than 10%. Finally, no interference was observed with other psychotic drugs encountered in acute poisoning. This rapid method (run time <10 min) was used to manage four voluntary intoxications involving venlafaxine.
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Affiliation(s)
- M Matoga
- Pharmacochimie, EA 2962, Université Bordeaux 2 Victor Segalen, France
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Daniel WA, Syrek M, Haduch A, Wójcikowski J. The effect of selective serotonin reuptake inhibitors (SSRIs) on the pharmacokinetics and metabolism of perazine in the rat. J Pharm Pharmacol 2001; 53:449-61. [PMID: 11341361 DOI: 10.1211/0022357011775749] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
The aim of this study was to investigate the effect of three selective serotonin reuptake inhibitors (SSRIs), fluoxetine, fluvoxamine and sertraline, on the pharmacokinetics and metabolism of perazine in a steady state in rats. Perazine (10 mg kg(-1), i.p.) was administered twice daily for two weeks, alone or jointly with one of the SSRIs. Concentrations of perazine and its two main metabolites (N-desmethylperazine and 5-sulfoxide) in the plasma and brain were measured 30 min and 6 and 12 h after the last dose of the drugs. Of the investigated SSRIs, fluoxetine and fluvoxamine significantly increased plasma and brain concentrations of perazine (up to 900% and 760% of the control value, respectively), their effect being most pronounced after 30 min and 6 h. Moreover, simultaneous increases in perazine metabolites concentrations and in the perazine/metabolite concentration ratios were observed. Sertraline elevated plasma and brain concentrations of perazine after 30 min. In-vitro studies with liver microsomes of rats treated chronically with perazine, SSRIs ortheir combinations showed decreased concentrations of cytochrome P-450 after perazine and a combination of perazine and fluvoxamine (vs control), and increased concentration after a combination of perazine and fluoxetine (vs perazine-treated group). Prolonged treatment with perazine did not significantly change the rate of its own metabolism. Chronic administration of fluoxetine or sertraline, alone or in a combination with perazine, accelerated perazine N-demethylation (vs control or perazine group, respectively). Fluvoxamine had a similar effect. The 5-sulfoxidation of perazine was accelerated by fluvoxamine and sertraline treatment, but the process was inhibited by administration of a combination of perazine and fluoxetine or fluvoxamine (vs control). Kinetic studies using control liver microsomes, in the absence or presence of SSRIs added in-vitro, demonstrated competitive inhibition of both N-demethylation and sulfoxidation by the investigated SSRIs. Sertraline was the most potent inhibitor of perazine N-demethylation but the weakest inhibitor of sulfoxidation. Results of in-vivo and in-vitro studies indicate that the observed interaction between perazine and SSRIs mainly involves competition for an active site of perazine N-demethylase and sulfoxidase. Moreover, increases in the concentrations of both perazine and metabolites measured, produced by the investigated drug combinations in-vivo, suggest simultaneous inhibition of another, yet to be investigated, metabolic pathway of perazine (e.g. aromatic hydroxylation).
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Affiliation(s)
- W A Daniel
- Polish Academy of Sciences, Institute of Pharmacology, Kraków.
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Carrillo JA, Benitez J. Clinically significant pharmacokinetic interactions between dietary caffeine and medications. Clin Pharmacokinet 2000; 39:127-53. [PMID: 10976659 DOI: 10.2165/00003088-200039020-00004] [Citation(s) in RCA: 181] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Caffeine from dietary sources (mainly coffee, tea and soft drinks) is the most frequently and widely consumed CNS stimulant in the world today. Because of its enormous popularity, the consumption of caffeine is generally thought to be safe and long term caffeine intake may be disregarded as a medical problem. However, it is clear that this compound has many of the features usually associated with a drug of abuse. Furthermore, physicians should be aware of the possible contribution of dietary caffeine to the presenting signs and symptoms of patients. The toxic effects of caffeine are extensions of their pharmacological effects. The most serious caffeine-related CNS effects include seizures and delirium. Other symptoms affecting the cardiovascular system range from moderate increases in heart rate to more severe cardiac arrhythmia. Although tolerance develops to many of the pharmacological effects of caffeine, tolerance may be overwhelmed by the nonlinear accumulation of caffeine when its metabolism becomes saturated. This might occur with high levels of consumption or as the result of a pharmacokinetic interaction between caffeine and over-the-counter or prescription medications. The polycyclic aromatic hydrocarbon-inducible cytochrome P450 (CYP) 1A2 participates in the metabolism of caffeine as well as of a number of clinically important drugs. A number of drugs, including certain selective serotonin reuptake inhibitors (particularly fluvoxamine), antiarrhythmics (mexiletine), antipsychotics (clozapine), psoralens, idrocilamide and phenylpropanolamine, bronchodilators (furafylline and theophylline) and quinolones (enoxacin), have been reported to be potent inhibitors of this isoenzyme. This has important clinical implications, since drugs that are metabolised by, or bind to, the same CYP enzyme have a high potential for pharmacokinetic interactions due to inhibition of drug metabolism. Thus, pharmacokinetic interactions at the CYP1A2 enzyme level may cause toxic effects during concomitant administration of caffeine and certain drugs used for cardiovascular, CNS (an excessive dietary intake of caffeine has also been observed in psychiatric patients), gastrointestinal, infectious, respiratory and skin disorders. Unless a lack of interaction has already been demonstrated for the potentially interacting drug, dietary caffeine intake should be considered when planning, or assessing response to, drug therapy. Some of the reported interactions of caffeine, irrespective of clinical relevance, might inadvertently cause athletes to exceed the urinary caffeine concentration limit set by sports authorities at 12 mg/L. Finally, caffeine is a useful and reliable probe drug for the assessment of CYP1A2 activity, which is of considerable interest for metabolic studies in human populations.
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Affiliation(s)
- J A Carrillo
- Department of Pharmacology and Psychiatry, Medical School, University of Extremadura, Badajoz, Spain.
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24
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Charlier C, Pinto E, Ansseau M, Plomteux G. Relationship between clinical effects, serum drug concentration, and concurrent drug interactions in depressed patients treated with citalopram, fluoxetine, clomipramine, paroxetine or venlafaxine. Hum Psychopharmacol 2000; 15:453-459. [PMID: 12404307 DOI: 10.1002/1099-1077(200008)15:6<453::aid-hup228>3.0.co;2-f] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The relationship between clinical effects and plasma concentrations of citalopram, fluoxetine, clomipramine, paroxetine and venlafaxine was studied in 119 cases of major depression. Clinical effects were evaluated using the Clinical Global Impression (CGI) improvement scale. Antidepressants were quantified by a separative chromatographic methodology. Plasma concentrations in responder patients were compared with the plasma concentrations proposed in literature as effective values. We found that the usual therapeutic window is convenient for citalopram and clomipramine, but could be reduced for fluoxetine and increased for venlafaxine and paroxetine. Concurrent drug interactions were also evaluated and clomipramine or citalopram plasma levels were found to be influenced by the presence of associated drugs. A larger study is needed, taking into account not only plasma concentrations and clinical effects, but also some pharmacokinetic data, especially the metabolic activity characterising the patient, and the presence or not of associated drugs. Copyright 2000 John Wiley & Sons, Ltd.
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Affiliation(s)
- C. Charlier
- University of Liège, Toxicology Laboratory, CHU Sart Tilman, B-4000 Liège, Belgium
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25
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Mace S, Taylor D. Selective serotonin reuptake inhibitors: a review of efficacy and tolerability in depression. Expert Opin Pharmacother 2000; 1:917-33. [PMID: 11249500 DOI: 10.1517/14656566.1.5.917] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Selective serotonin reuptake inhibitors (SSRIs) are now generally regarded as effective and better tolerated alternatives to tricyclic antidepressants (TCAs) for the treatment of depression. SSRIs also seem to be as well tolerated as moclobemide, mirtazapine, venlafaxine, reboxetine and nefazodone and show comparable efficacy. Minor differences have been observed between some SSRIs and some of the newer antidepressants but these findings are far from conclusive. Widespread use of the SSRIs has highlighted some unforseen adverse effects associated with SSRIs, namely hyponatraemia, EPSE and sexual dysfunction. Overall, differences in efficacy and tolerability between individual SSRIs are small and clinically insignificant.
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Affiliation(s)
- S Mace
- Pharmacy Dept, Maudsley Hospital, Denmark Hill, London SE5 8AZ, UK
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26
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Rasmussen BB, Brøsen K. Is therapeutic drug monitoring a case for optimizing clinical outcome and avoiding interactions of the selective serotonin reuptake inhibitors? Ther Drug Monit 2000; 22:143-54. [PMID: 10774624 DOI: 10.1097/00007691-200004000-00001] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The selective serotonin reuptake inhibitors (SSRIs) comprise citalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline and they differ from each other in chemical structure, by pharmacokinetic properties and, most importantly, with respect to enzyme-specific metabolism and interactions. Citalopram is administered as a racemic mixture. The drug is oxidated to desmethylcitalopram in the liver, partially by CYP2C19 and partially by CYP3A4. Fluoxetine is administered as a racemate of R- and S-fluoxetine. Both R- and S-fluoxetine are metabolized by CYP2D6 to the active metabolites R- and S-norfluoxetine. Fluvoxamine is metabolized to inactive metabolites by CYP1A2 and CYP2D6. Paroxetine is metabolized to inactive metabolites partially by CYP2D6, and accordingly the metabolism of paroxetine is dependent on the genetic polymorphism of CYP2D6. Sertraline is metabolized to desmethylsertraline, probably by CYP3A4. Several analytical methods have been described for all SSRIs. Most assays are based on separation by high-performance liquid chromatography or gas chromatography. Stereoselective methods for the analysis of racemic citalopram and fluoxetine have been published. The SSRIs are generally well tolerated and their therapeutic indices are large. In several studies there has not been found a clear relationship between clinical efficacy and plasma concentration, nor any threshold that defines toxic concentrations. The available data do not suggest that any benefit be obtained from routine monitoring of SSRI plasma levels. Therefore therapeutic drug monitoring (TDM) of the SSRIs may be useful mainly in situations where poor compliance is suspected and when therapeutic failure or toxic events are experienced at clinically relevant dosages. Further, in special populations, such as in elderly patients, poor metabolizers of sparteine (CYP2D6) or mephenytoin (CYP2C19), and patients with liver impairment, the measurement of plasma concentrations may be useful.
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Affiliation(s)
- B B Rasmussen
- Clinical Pharmacology, Institute of Public Health, University of Southern Denmark--Odense University
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Affiliation(s)
- J Willetts
- Palanquin Corporation, Florida, New York, USA
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28
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Sánchez C, Hyttel J. Comparison of the effects of antidepressants and their metabolites on reuptake of biogenic amines and on receptor binding. Cell Mol Neurobiol 1999; 19:467-89. [PMID: 10379421 DOI: 10.1023/a:1006986824213] [Citation(s) in RCA: 299] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
1. The present survey compares the effects of antidepressants and their principal metabolites on reuptake of biogenic amines and on receptor binding. The following antide-pressants were included in the study: the tricyclic antidepressants amitriptyline, dothiepin, and lofepramine and the atypical antidepressant bupropion, which all have considerable market shares in the UK and/or US markets; the selective serotonin reuptake inhibitors (SSRIs) citalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline; and the recently approved antidepressants venlafaxine and nefazodone. 2. Amitriptyline has similar in vitro reuptake inhibitory potencies for 5-HT and NA, whereas the metabolite nortriptyline is preferentially a NA reuptake inhibitor. Both amitriptyline and nortriptyline are also 5-HT2 receptor antagonists. 3. Dothiepin has equipotent 5-HT and NA reuptake inhibitory activity, whereas northiaden shows a slight selectivity for NA reuptake inhibition. Dothiepin and northiaden are also 5-HT2 receptor antagonists. The slow elimination rate of northiaden (36-46 hr) compared to dothiepin (14-24 hr) suggests that northiaden contributes significantly to the therapeutic effect of dothiepin. 4. Lofepramine is extensively metabolized to desipramine. Desipramine plays an important role in the antidepressant activity of lofepramine, as the plasma elimination half-life of lofepramine (4-6 hr) is much shorter than that of desipramine (24 hr). Both compounds are potent and selective inhibitors of NA reuptake. 5. The five approved SSRIs, citalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline, are potent 5-HT reuptake inhibitors, and the demethyl metabolites, norfluoxetine, demethylsertraline, and demethylcitalopram, also show selectivity. Paroxetine and sertraline are the most potent inhibitors of 5-HT reuptake, whereas citalopram is the most selective. Fluoxetine is the least selective and the metabolite of fluoxetine, norfluoxetine, is a more selective and more potent 5-HT reuptake inhibitor than the parent compound and has an extremely long half-life (7-15 compared to 1-3 days). Thus the metabolite plays an important role for the therapeutic effect of fluoxetine. Fluoxetine is also a 5-HT2C receptor antagonist. Demethylsertraline is a weaker and less selective 5-HT reuptake inhibitor in vitro than sertraline, but demethylsertraline has a very long half-life (62-104 hr) compared to the parent compound (24 hr) and it might play a role in the therapeutic effects of sertraline. Demethylcitalopram has about a 10 times lower 5-HT reuptake inhibitory potency in vitro than citalopram, and the elimination half-lives are approximately 1.5 and 2 days, respectively. 6. Bupropion and hydroxybupropion are weak inhibitors of biogenic amine reuptake. The mechanisms of action responsible for the clinical effects of bupropion are not fully understood, but it has been suggested that both dopaminergic and noradrenergic components play a role and that the hydroxybupropion metabolite contributes significantly to the antidepressant activity. 7. Venlafaxine and O-demethylvenlafaxine are weak inhibitors of 5-HT and NA reuptake, and the selectivity ratios are close to one. O-Demethylvenlafaxine is eliminated more slowly than venlafaxine (plasma half-lives of 5 and 11 hr, respectively), and it is likely that it contributes to the overall therapeutic effect of venlafaxin. 8. Nefazodone and alpha-hydroxynefazodone are equipotent 5-HT and NA reuptake inhibitors. Both compounds are also 5-HT2 receptor antagonists. Both parent compound and metabolite have short elimination half-lives.
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MESH Headings
- Animals
- Antidepressive Agents/metabolism
- Antidepressive Agents/pharmacology
- Antidepressive Agents/therapeutic use
- Antidepressive Agents, Second-Generation/metabolism
- Antidepressive Agents, Second-Generation/pharmacology
- Antidepressive Agents, Second-Generation/therapeutic use
- Antidepressive Agents, Tricyclic/metabolism
- Antidepressive Agents, Tricyclic/pharmacokinetics
- Binding, Competitive/drug effects
- Biogenic Amines/metabolism
- Depression/drug therapy
- Depression/metabolism
- Humans
- Receptors, Catecholamine/drug effects
- Receptors, Catecholamine/metabolism
- Receptors, Serotonin/drug effects
- Receptors, Serotonin/metabolism
- Selective Serotonin Reuptake Inhibitors/metabolism
- Selective Serotonin Reuptake Inhibitors/pharmacology
- Selective Serotonin Reuptake Inhibitors/therapeutic use
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29
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Rotzinger S, Bourin M, Akimoto Y, Coutts RT, Baker GB. Metabolism of some "second"- and "fourth"-generation antidepressants: iprindole, viloxazine, bupropion, mianserin, maprotiline, trazodone, nefazodone, and venlafaxine. Cell Mol Neurobiol 1999; 19:427-42. [PMID: 10379419 DOI: 10.1023/a:1006953923305] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
1. This review summarizes the major known aspects of the metabolism of second-generation (iprindole, viloxazine, bupropion, mianserin, maprotiline, and trazodone) and fourth-generation (nefazodone and venlafaxine) antidepressants. 2. Discussions about specific enzymes involved and about possible pharmacokinetic drug-drug interactions, particularly as they relate to cytochrome P450 enzymes, are provided.
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Affiliation(s)
- S Rotzinger
- Department of Psychiatry, University of Alberta, Edmonton, Canada
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30
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Serretti A, Franchini L, Gasperini M, Rampoldi R, Smeraldi E. Mode of inheritance in mood disorder families according to fluvoxamine response. Acta Psychiatr Scand 1998; 98:443-50. [PMID: 9879785 DOI: 10.1111/j.1600-0447.1998.tb10117.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mood disorders are known to cluster within families, but the mode of transmission remains largely unknown. The purpose of our analysis was to determine whether selection of a sample that was homogeneous in its response to an antidepressant provided stronger evidence for a single major locus. Complex segregation analysis was applied to a sample of 171 Italian families of bipolar and unipolar probands that were responsive to the antidepressant fluvoxamine. We used regressive logistic analyses to determine the best fit from among environmental, arbitrary Mendelian, dominant, recessive and additive models. For the 171 affective families with probands that were responsive to the antidepressant fluvoxamine, a Mendelian model of inheritance was rejected. When considering 68 families of bipolar probands, the best fit was obtained for a Mendelian dominant model of transmission. The identification of a Mendelian mode of transmission in bipolar subjects who were selected according to their response to fluvoxamine supports the use of a pharmacological criterion as a tool for identifying true genetic disorders.
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Affiliation(s)
- A Serretti
- Istituto Scientifico H. San Raffaele, Department of Neuroscience, University of Milan School of Medicine, Italy
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31
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32
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Akerman KK, Jolkkonen J, Huttunen H, Penttilä I. High-performance liquid chromatography method for analyzing citalopram and desmethylcitalopram from human serum. Ther Drug Monit 1998; 20:25-9. [PMID: 9485550 DOI: 10.1097/00007691-199802000-00005] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
This report describes a sensitive and specific method for analyzing a serotonin reuptake blocker, citalopram, and its active metabolite, desmethylcitalopram, in human serum. For high-performance liquid chromatography (HPLC) analysis, samples and standards are prepared with ASPEC automatic sample preparator using 100 mg Bond-Elut C-18 solid-phase extraction columns. The method is an isocratic HPLC method with a mobile phase of acetonitrile:methanol:50 mM dipotassium hydrogenphosphate, pH 4.7 (40:100). Detection is performed with diode array detector at 220 nm and the peak purity analyses at 210 to 365 nm. The intraassay coefficient of variation ranges from 3.7% to 7.3%, and the interassay coefficient of variation ranges from 6.9% to 9.9% at therapeutic drug concentrations. The detection limit is 15 nmol/l. The method is suitable for therapeutic drug monitoring in a clinical laboratory. A clear correlation, r = 0.72 (y = 0.36x + 17.94), between citalopram and its metabolite levels is observed in routine therapeutic drug monitoring service. A linear correlation between serum concentration and daily dose of citalopram in patient groups is also observed.
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Affiliation(s)
- K K Akerman
- Department of Clinical Chemistry, Kuopio University Hospital, Finland
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33
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Preskorn SH. Clinically relevant pharmacology of selective serotonin reuptake inhibitors. An overview with emphasis on pharmacokinetics and effects on oxidative drug metabolism. Clin Pharmacokinet 1997; 32 Suppl 1:1-21. [PMID: 9068931 DOI: 10.2165/00003088-199700321-00003] [Citation(s) in RCA: 250] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
This paper presents an overview of the clinically relevant pharmacology of selective serotonin reuptake inhibitors (SSRIs) with an emphasis on their pharmacokinetics and effects on cytochrome P450 (CYP) enzymes. The SSRIs are potent inhibitors of the neuronal reuptake pump for serotonin (5-hydroxytryptamine; 5-HT) and have minimal effects on a number of other sites of actions (e.g. neuroreceptors and fast sodium channels). For this reason, drugs in this class have remarkable similarity as regards acute and maintenance antidepressant efficacy and tolerability profile. However, individual members of this class differ substantially in their pharmacokinetics and effects on CYP enzymes. Most SSRIs have a half-life (t1/2) of approximately 1 day. Fluoxetine, however, has a longer t1/2 of 2 to 4 days, and its active metabolite, norfluoxetine, has an extended t1/2 of 7 to 15 days. Fluoxetine, paroxetine and, to a lesser extent, fluvoxamine inhibit their own metabolism. That is not the case for citalopram or sertraline. There are nonlinear increases in paroxetine plasma concentrations with dosage increases, but proportional changes with citalopram and sertraline. Indirect data suggest that fluoxetine and fluvoxamine also have nonlinear pharmacokinetics over their usual dosage range. Age-related increases in plasma drug concentrations for citalopram (approximately 130%) and paroxetine (approximately 50 to 100%) have been observed in healthy elderly (65 to 75 years) persons versus those who are younger. There is an age-gender interaction for sertraline, with its plasma concentrations being 35 to 40% lower in young men than in elderly or young females or elderly males. While there is no apparent change in fluvoxamine plasma levels as a function of age, plasma drug concentrations are 40 to 50% lower in males than in females. Limited data from clinical trials suggest that age-related differences with fluoxetine may be comparable to those of citalopram and paroxetine. Marked differences exist between the SSRIs with regard to effects on specific CYP enzymes and, thus, the likelihood of clinically important pharmacokinetic drug-drug interactions. The most extensive in vitro and in vivo research has been done with fluoxetine, fluvoxamine and sertraline; there has been less with paroxetine and citalopram. The available in vivo data at each drug's usually effective antidepressant dose are summarised below. Citalopram produces mild inhibition of CYP2D6. Fluvoxamine produces inhibition (which would be expected to be clinically meaningful) of two CYP enzymes. CYP1A2 and CYP2C19, and probably a third, CYP3A3/4. Fluoxetine substantially inhibits CYP2D6 and probably CYP2C9/10, moderately inhibits CYP2C19 and mildly inhibits CYP3A3/4. Paroxetine substantially inhibits CYP2D6 but doses not appear to inhibit any other CYP enzyme. Sertraline produces mild inhibition of CYP2D6 but has little, if any, effect on CYP1A2, CYP2C9/10, CYP2C19 or CYP3A3/4. Understanding the similarities and differences in the pharmacology of SSRIs can aid the clinician in optimal use of this important class of antidepressants.
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Affiliation(s)
- S H Preskorn
- Department of Psychiatry, University of Kansas School of Medicine, Wichita, USA
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34
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Baumann P. Pharmacokinetic-pharmacodynamic relationship of the selective serotonin reuptake inhibitors. Clin Pharmacokinet 1996; 31:444-69. [PMID: 8968657 DOI: 10.2165/00003088-199631060-00004] [Citation(s) in RCA: 158] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The recently introduced antidepressants, the selective serotonin reuptake inhibitors (SSRIs) [citalopram, fluoxetine, fluvoxamine, paroxetine and sertraline], are known for their clinical efficacy, good tolerability and relative safety. They differ from each other in chemical structure, metabolism and pharmacokinetic properties. Therapeutic drug monitoring of these compounds is not widely used, as the plasma concentration ranges within which clinical response with minimal adverse effects appears to be optimal are not clearly defined. Almost all recent assays developed for the quantitative determination of SSRIs and their metabolites in blood are based either on the separation of SSRIs by high performance liquid chromatography (HPLC) or gas chromatography (GC). Citalopram and fluoxetine have been introduced as racemic compounds. There are some differences in the pharmacological profile, metabolism and pharmacokinetics between the enantiomers of the parent compounds and their demethylated metabolites. Stereoselective chromatographic methods for their analysis in blood are now available. With regard to the SSRIs presently available, no clearcut plasma concentration-clinical effectiveness relationship in patients with depression has been shown, nor any threshold which defines toxic concentrations. This may be explained by their low toxicity and use at dosages where serious adverse effects do not appear. SSRIs vary widely in their qualitative and quantitative interaction with cytochrome P450 (CYP) isozymes in the liver. CYP2D6 is inhibited by SSRIs, in order of decreasing potency paroxetine, norfluoxetine, fluoxetine, sertraline, citalopram and fluvoxamine. This may have clinical consequences with some but not all SSRIs, when they are taken with tricyclic antidepressants. Except for citalopram and paroxetine, little is known about the enzymes which control the biotransformation of the SSRIs. There have been many reports on marked pharmacokinetic interactions between fluoxetine and tricyclic antidepressants. Fluoxetine has a stronger effect on their hydroxylation than on their demethylation. Interactions observed between fluoxetine and alprazolam, midazolam and carbamazepine seem to occur on the level of CYP3A. Fluvoxamine strongly inhibits the N-demethylation of some tricyclic antidepressants of the tertiary amine type and of clozapine. This may lead to adverse effects but augmentation with fluvoxamine can also improve response in very rapid metabolisers, as it increases the bioavailability of the comedication. Fluvoxamine inhibits with decreasing potency, CYP1A2, CYP2C19, CYP2D6 and CYP1A1, but it is also an inhibitor of CYP3A. Fluoxetine and fluvoxamine have shown to increase methadone plasma concentrations in dependent patients. Some authors warn about a combination of monoamine oxidase (MAO) inhibitors with SSRIs, as this could lead to a serotonergic syndrome. Studies with healthy volunteers suggest, however, that a combination of moclobemide and SSRIs, such as fluvoxamine, should not present serious risks in promoting a serotonin syndrome. A combination of moclobemide and fluvoxamine has successfully been used in refractory depression, but more studies are needed, including plasma-concentration monitoring, before this combined treatment can be recommended. Paroxetine is a substrate of CYP2D6, but other enzyme(s) could also be involved. Its pharmacokinetics are linear in poor metabolisers of sparteine, and non-linear in extensive metabolisers. Due to its potent CYP2D6 inhibiting properties, comedication with this SSRI can lead to an increase of tricyclic antidepressants in plasma, as shown with amitriptyline and trimipramine. CYP3A has been claimed to be involved in the biotransformation of sertraline to norsertraline. Clinical investigations (with desipramine) confirmed in vitro findings that CYP2D6 inhibition by sertraline is only moderate. (ABSTRACT TRUNCATED)
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Affiliation(s)
- P Baumann
- Départment Universitaire de Psychiatrie Adulte, Prilly-Lausanne, Switzerland.
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35
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Eap CB, Baumann P. Analytical methods for the quantitative determination of selective serotonin reuptake inhibitors for therapeutic drug monitoring purposes in patients. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL APPLICATIONS 1996; 686:51-63. [PMID: 8953192 DOI: 10.1016/s0378-4347(96)00338-6] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Five selective serotonin reuptake inhibitors (SSRIs) have been introduced recently: citalopram, fluoxetine, fluvoxamine, paroxetine and sertraline. Although no therapeutic window has been defined for SSRIs, in contrast to tricyclic antidepressants, analytical methods for therapeutic drug monitoring of SSRIs are useful in several instances. SSRIs differ widely in their chemical structure and in their metabolism. The fact that some of them have N-demethylated metabolites, which are also SSRIs, requires that methods be available which allow therapeutic drug monitoring of the parent compounds and of these active metabolites. most procedures are based on prepurification of the SSRIs by liquid-liquid extraction before they are submitted to separation by chromatographic procedures (high-performance liquid chromatography, gas chromatography, thin layer chromatography) and detection by various detectors (UV, fluorescence, electrochemical detector, nitrogen-phosphorus detector, mass spectrometry). This literature review shows that most methods allow quantitative determination of SSRIs in plasma, in the lower ng/ml range, and that they are, therefore, suitable for therapeutic drug monitoring purposes of this category of drugs.
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Affiliation(s)
- C B Eap
- Département Universitaire de Psychiatrie Adulte, Prilly-Lausanne, Switzerland
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36
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Affiliation(s)
- P J Goodnick
- Department of Psychiatry, University of Miami, FL, USA
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37
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Abstract
The pharmacokinetics of fluvoxamine, a selective serotonin reuptake inhibitor (SSRI) with antidepressant properties, are well established. After oral administration, the drug is almost completely absorbed from the gastrointestinal tract, and the extent of absorption is unaffected by the presence of food. Despite complete absorption, oral bioavailability in man is approximately 50% on account of first-pass hepatic metabolism. Peak plasma fluvoxamine concentrations are reached 4 to 12 hours (enteric-coated tablets) or 2 to 8 hours (capsules, film-coated tablets) after administration. Steady-state plasma concentrations are achieved within 5 to 10 days after initiation of therapy and are 30 to 50% higher than those predicted from single dose data. Fluvoxamine displays nonlinear steady-state pharmacokinetics over the therapeutic dose range, with disproportionally higher plasma concentrations with higher dosages. Plasma fluvoxamine concentrations show no clear relationship with antidepressant response or severity of adverse effects. Fluvoxamine undergoes extensive oxidative metabolism, most probably in the liver. Nine metabolites have been identified, none of which are known to be pharmacologically active. The specific cytochrome P450 (CYP) isoenzymes involved in the metabolism of fluvoxamine are unknown. CYP2D6, which is crucially involved in the metabolism of paroxetine and fluoxetine, appears to play a clinically insignificant role in the metabolism of fluvoxamine. The drug is excreted in the urine, predominantly as metabolites, with only negligible amounts ( < 4%) of the parent compound. Fluvoxamine shows a biphasic pattern of elimination with a mean terminal elimination half-life of 12 to 15 hours after a single oral dose; this is prolonged by 30 to 50% at steady-state. Plasma protein binding of fluvoxamine (77%) is low compared with that of other SSRIs. Fluvoxamine pharmacokinetics are substantially unaltered by increased age or renal impairment. However, its elimination is prolonged in patients with hepatic cirrhosis. Fluvoxamine inhibits oxidative drug metabolising enzymes (particularly CYP1A2, and less potently and much less potently CYP3A4 and CYP2D6, respectively) and has the potential for clinically significant drug interactions. Drugs whose metabolic elimination is impaired by fluvoxamine include tricyclic antidepressants (tertiary, but not secondary, amines), alprazolam, bromazepam, diazepam, theophylline, propranolol, warfarin and, possibly, carbamazepine. Fluvoxamine is a second generation antidepressant that selectively inhibits neuronal reuptake of serotonin (5-hydroxytryptamine; 5-HT). Fluvoxamine exhibits antidepressant activity similar to that of the tricyclic antidepressants, but has a somewhat improved tolerability profile, particularly with respect to a lower incidence of anticholinergic effects and reduced cardiotoxic potential. However, gastrointestinal adverse effects, especially nausea, are seen more frequently with fluvoxamine than with the tricyclic antidepressants. Fluvoxamine does not have an asymmetric carbon in its structure (fig. 1) and therefore does not exist as optical isomers. For this reason, the potentially confounding problem of stereoisomerism does not arise with fluvoxamine.
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Affiliation(s)
- J van Harten
- Department of Clinical Pharmacology, Solvay Duphar BV, Weesp, The Netherlands
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