Clinically significant pharmacokinetic drug interactions with psychoactive drugs: antidepressants and antipsychotics and the cytochrome P450 system

N-acetyl Cysteine Overdose Induced Acute Toxicity and Hepatic Microvesicular Steatosis by Disrupting GSH and Interfering Lipid Metabolisms in Normal Mice

N-acetyl cysteine (NAC) is a versatile drug used in various conditions, but the limitations and toxicities are not clear. The acute toxicity and toxicological mechanisms of an intraperitoneal injection of NAC in normal mice were deciphered. The LD50 for male and female BALB/cByJNarl mice were 800 mg/kg and 933 mg/kg. The toxicological mechanisms of 800 mg/kg NAC (N800) were investigated. The serum biomarkers of hepatic and renal indices dramatically increased, followed by hepatic microvesicular steatosis, renal tubular injury and necrosis, and splenic red pulp atrophy and loss. Thus, N800 resulted in mouse mortality mainly due to acute liver, kidney, and spleen damages. The safe dose (275 mg/kg) of NAC (N275) increased hepatic antioxidant capacity by increasing glutathione levels and catalase activity. N275 elevated the hepatic gene expressions of lipid transporter, lipid synthesis, β-oxidation, and ketogenesis, suggesting a balance between lipid production and consumption, and finally, increased ATP production. In contrast, N800 increased hepatic oxidative stress by decreasing glutathione levels through suppressing Gclc, and reducing catalase activity. N800 decreased the hepatic gene expressions of lipid transporter, lipid synthesis, and interferred β-oxidation, leading to lipid accumulation and increasing Cyp2E1 expression, and finally, decreased ATP production. Therefore, NAC doses are limited for normal individuals, especially via intraperitoneal injection or similar means.

Evaluation of the passive permeability of antidepressants through pore-suspended lipid bilayer

HYPOTHESIS

The antidepressant drug imipramine, and its metabolite desipramine show different extents of interaction with, and passive permeation through, cellular membrane models, with the effects depending on the membrane composition. Through multimodal interrogation, we can observe that the drugs have a direct impact on the physicochemical properties of the membrane, that may play a role in their pharmacokinetics.

EXPERIMENTS

Microcavity pore-suspended lipid bilayers (MSLBs) of four different compositions, each with a different headgroup charge namely; zwitterionic dioleoylphosphatidylcholine (DOPC), mixed DOPC and negatively charged dioleoylphosphatidylglycerol (DOPG) (3:1), mixed DOPC and positively charged dioleoyltrimethylammoniumpropane (DOTAP) (3:1), and with increasing complex composition mimicking blood-brain-barrier (BBB) were prepared on gold and polydimethylsiloxane (PDMS) substrates using a Langmuir-Blodgett-vesicle fusion method. The molecular interaction and permeation of antidepressants, imipramine, and its metabolite desipramine with the lipid bilayers were evaluated using highly sensitive label-free electrochemical impedance spectroscopy (EIS) and surface-enhanced Raman spectroscopy (SERS). Drug-induced membrane packing/fluidity alterations were assessed using fluorescence lifetime imaging (FLIM) and fluorescence lifetime correlation spectroscopy (FLCS) of MSLB over microfluidic PDMS array.

FINDINGS

Using EIS to evaluate in real-time membrane admittance changes, we found that imipramine greatly increases the ion permeability of negatively charged DOPC:DOPG (3:1) membranes. The effect was observed also at neutral (DOPC) and to a lesser extent at positively charged DOPC:DOTAP(3:1) membranes. In contrast, desipramine had a much weaker impact on ion permeability across all bilayer compositions. Temporal capacitance data show that desipramine intercalates at negatively charged membrane thereby increasing the thickness of the membrane. The overall kinetics of the imipramine permeation is higher than that of desipramine. This was confirmed using SERS, which also provides an evaluation of drug passive permeation based on arrival time across the membrane. Using FLCS, we found that imipramine increases the lipid membrane fluidity, whereas desipramine lowers it, with the exception of the negatively charged membrane. A translocation rate pharmacokinetics model was established for the first time at the MSLB platform by real-time monitoring of the variation in membrane resistance of pristine DOPC and blood-brain-barrier (BBB) membrane.

Sex/Gender- and Age-Related Differences in β-Adrenergic Receptor Signaling in Cardiovascular Diseases

Sex differences in cardiovascular disease (CVD) are often recognized from experimental and clinical studies examining the prevalence, manifestations, and response to therapies. Compared to age-matched men, women tend to have reduced CV risk and a better prognosis in the premenopausal period. However, with menopause, this risk increases exponentially, surpassing that of men. Although several mechanisms have been provided, including sex hormones, an emerging role in these sex differences has been suggested for β-adrenergic receptor (β-AR) signaling. Importantly, β-ARs are the most important G protein-coupled receptors (GPCRs), expressed in almost all the cell types of the CV system, and involved in physiological and pathophysiological processes. Consistent with their role, for decades, βARs have been considered the first targets for rational drug design to fight CVDs. Of note, β-ARs are seemingly associated with different CV outcomes in females compared with males. In addition, even if there is a critical inverse correlation between β-AR responsiveness and aging, it has been reported that gender is crucially involved in this age-related effect. This review will discuss how β-ARs impact the CV risk and response to anti-CVD therapies, also concerning sex and age. Further, we will explore how estrogens impact β-AR signaling in women.

Use of central nervous system drugs in combination with selective serotonin reuptake inhibitor treatment: A Bayesian screening study for risk of suicidal behavior

BACKGROUND

Using other central nervous system (CNS) medications in combination with selective serotonin reuptake inhibitor (SSRI) treatment is common. Despite this, there is limited evidence on the impact on suicidal behavior of combining specific medications. We aim to provide evidence on signals for suicidal behavior risk when initiating CNS drugs during and outside of SSRI treatment.

MATERIALS AND METHODS

Using a linkage of Swedish national registers, we identified a national cohort of SSRI users aged 6-59 years residing in Sweden 2006-2013. We used a two-stage Bayesian Poisson model to estimate the incidence rate ratio (IRR) of suicidal behavior in periods up to 90 days before and after a CNS drug initiation during SSRI treatment, while accounting for multiple testing. For comparison, and to assess whether there were interactions between SSRIs and other CNS drugs, we also estimated the IRR of initiating the CNS drug without SSRI treatment.

RESULTS

We identified 53 common CNS drugs initiated during SSRI treatment, dispensed to 262,721 individuals. We found 20 CNS drugs with statistically significant IRRs. Of these, two showed a greater risk of suicidal behavior after versus before initiating the CNS drug (alprazolam, IRR = 1.39; flunitrazepam, IRR = 1.83). We found several novel signals of drugs that were statistically significantly associated with a reduction in the suicidal behavior risk. We did not find evidence of harmful interactions between SSRIs and the selected CNS drugs.

CONCLUSION

Several of the detected signals for reduced risk correspond to drugs where there is previous evidence of benefit for antidepressant augmentation (e.g., olanzapine, quetiapine, lithium, buspirone, and mirtazapine). Novel signals of reduced suicidal behavior risk, including for lamotrigine, valproic acid, risperidone, and melatonin, warrant further investigation.

Sex- and Gender-Based Pharmacological Response to Drugs

In humans, the combination of all sex-specific genetic, epigenetic, and hormonal influences of biologic sex produces different in vivo environments for male and female cells. We dissect how these influences of sex modify the pharmacokinetics and pharmacodynamics of multiple drugs and provide examples for common drugs acting on specific organ systems. We also discuss how gender of physicians and patients may influence the therapeutic response to drugs. We aim to highlight sex as a genetic modifier of the pharmacological response to drugs, which should be considered as a necessary step toward precision medicine that will benefit men and women. SIGNIFICANCE STATEMENT: This study discusses the influences of biologic sex on the pharmacokinetics and pharmacodynamics of drugs and provides examples for common drugs acting on specific organ systems. This study also discusses how gender of physicians and patients influence the therapeutic response to drugs.

Prescribing patterns of psychotropic medications in psychiatric disorders: a descriptive study from Palestine

Background The practice patterns of psychiatrists have changed over the last two decades. Objectives This study describes the pattern of prescribing psychotropic drugs in treating common psychiatric disorders, and investigates the rate of polypharmacy and potential drug-drug interactions. Setting Psychiatry governmental outpatient clinic in the north of West Bank, Palestine. Methods Cross-sectional study that included all prescriptions which were issued over the period October 2018 to January 2019, for patients diagnosed with schizophrenia, depression, anxiety, bipolar disorder and schizoaffective disorders, and checked for the presence and the grade of potential drug-drug interactions using "Medscape drug interactions checker". Main outcome measure Prescribing patterns of psychotropic drugs. Results A total of 1045 prescriptions were examined. The mean age of the patients was 47.3 years (SD = 13.6), two-thirds of the patients (64.5%) were males. Fifty-two percent of the patients were diagnosed with schizophrenia while 15.2% were diagnosed with depression. The later third was diagnosed with bipolar disorder, schizoaffective and anxiety disorders (15.8%, 11.1% and 5.1% respectively). The most commonly prescribed drugs were typical antipsychotics for schizophrenia, bipolar and schizoaffective disorders, selective serotonin reuptake inhibitors for depression and tricyclic anti-depressants for anxiety. Polypharmacy was found in 877 prescriptions (84%), and drug-drug interactions (DDIs) were identified in 823 (94%) prescriptions. The DDIs were classified as minor (4, 0.5%), significant (418, 50.8%) and serious (401, 48.7%). Conclusions Our results suggest that the pharmacotherapy of psychiatric disorders in Palestine may not be in accordance to international guidelines and the incidence of polypharmacy and DDIs is high.

Pharmacogenetic Testing Options Relevant to Psychiatry in Canada: Options de tests pharmacogénétiques pertinents en psychiatrie au Canada

OBJECTIVE

To identify and assess pharmacogenetic testing options relevant to psychiatry in Canada.

METHOD

Searches of published literature, websites, and Standard Council of Canada's Laboratory Directory were conducted to identify pharmacogenetic tests available in Canada. Identified tests were assessed on 8 key questions related to analytical validity, accessibility, test ordering, delivery of test results, turnaround time, cost, clinical trial evidence, and gene/allele content.

RESULTS

A total of 13 pharmacogenetic tests relevant to psychiatry in Canada were identified. All tests were highly accessible, and most were conducted in accredited laboratories. Both direct-to-consumer and clinician-gated testing were identified, with turnaround times and cost ranging from 2 to 40 days and CAD$199 to CAD$2310, respectively. Two tests were supported by randomized controlled trials. All tests met minimum gene and allele panel recommendations for psychiatry, but no 2 panels were identical. No test was unequivocally superior to all other tests.

CONCLUSIONS

Pharmacogenetic testing in Canada is readily available but highly variable in terms of ordering procedures, delivery of results, turnaround times, cost, and gene/allele content. As such, it is important for psychiatrists and other health-care providers to understand the differences between the available tests to ensure appropriate selection and implementation within their practice.

Ambulatory Pharmacotherapy of Five Psychiatric Disorders in Bahrain: a Descriptive Study

We examined the outpatient prescription pattern of psychotropic drugs used for the treatment of five major psychiatric diseases in Bahrain. Setting outpatient department of the main psychiatric hospital in Bahrain. Methods This was a retrospective, cross-sectional study in which we targeted randomly selected prescriptions (n = 992, 56.1% males, 43.9% females) from 1st of January until 31st of December, 2017. Main outcome measure the types of outpatient psychotropic drugs prescribed by the physicians. Results The pharmacotherapy of schizophrenia consisted of atypical anti-psychotics (92.8%), or typical anti-psychotics (17.8%). The anti-depressants used were: Selective-serotonin reuptake inhibiters (SSRIs) (41.6%), Serotonin-norepinephrine reuptake inhibiters (SNRIs) (34.5%), tricyclic anti-depressants (TCAs) (12.8%), and atypical anti-depressants (10.6%). Combination anti-depressants was employed in (12.4%) of cases. The pharmacotherapy for anxiety disorders was composed of benzodiazepines (59.5%), atypical anti-psychotics (45.2%), SSRIs (40.5%), SNRIs (28.6%), TCAs (14.3%), and anti-convulsants (16.7%) and atypical anti-psychotics (7.1). The medications prescribed for bipolar disorder were atypical anti-psychotics (78.6%), anti-convulsants (66.5%), benzodiazepines (27.7%), typical anti-psychotics (8.9%) and lithium (6.7%). Schizoaffective disorder patients received atypical anti-psychotics (97.3%), anti-convulsants (47.8%), benzodiazepines (27.4%), SNRIs (25.7%), SSRIs (15%), typical anti-psychotics (10.6%), atypical anti-depressants (10.6%) and TCAs (6.2%). A combination of antipsychotics and anti-depressants was employed in 33.6% and 4.7% of all subjects regardless of the diagnosis, respectively. Conclusions With a few exceptions, the pharmacotherapy of psychiatric diseases in Bahrain was in line with the latest recommendations. However, psychotropic polypharmacy was observed and calls for immediate attention.

Beverage-induced enhanced bioavailability of carbamazepine and its consequent effect on antiepileptic activity and toxicity

The present study was undertaken to investigate the food–drug interaction of carbamazepine (CBZ). Common fruit juices [grapefruit juice (GFJ), lime juice (LJ)], known to inhibit the enzyme cytochrome P450 3A4 (CYP3A4), and some widely consumed beverages [milk (M), black tea (BT)] were involved in this study in the presence of CBZ, as might happen during clinical therapy. The effects of the beverages on the pharmacokinetics and drug-induced toxicity of CBZ was observed after concomitant administration for a period of 28 days. Accordingly, the influence of altered bioavailability of CBZ on its antiepileptic activity was investigated. A significant shift in the C_max as well as T_max of CBZ was observed in the presence of LJ and GFJ. This increase in bioavailability significantly enhanced hepatotoxicity and delayed the onset of tremor and piloerection against pentylene tetrazole (PTZ)-induced seizure in experimental animals. However, increased toxicity of CBZ was found to be absent with BT. Thus, from our observation, LJ or GFJ in the presence of CBZ significantly increased the bioavailability of CBZ, which might lead to increased toxicity and antiepileptic activity of the drug.

Conversions of tricyclic antidepressants and antipsychotics with selected P450s from Sorangium cellulosum So ce56

Human cytochromes P450 (P450s) play a major role in the biotransformation of drugs. The generated metabolites are important for pharmaceutical, medical, and biotechnological applications and can be used for derivatization or toxicological studies. The availability of human drug metabolites is restricted and alternative ways of production are requested. For this, microbial P450s turned out to be a useful tool for the conversion of drugs and related derivatives. Here, we used 10 P450s from the myxobacterium Sorangium cellulosum So ce56, which have been cloned, expressed, and purified. The P450s were investigated concerning the conversion of the antidepressant drugs amitriptyline, clomipramine, imipramine, and promethazine; the antipsychotic drugs carbamazepine, chlorpromazine, and thioridazine, as well as their precursors, iminodibenzyl and phenothiazine. Amitriptyline, chlorpromazine, clomipramine, imipramine, and thioridazine are efficiently converted during the in vitro reaction and were chosen to upscale the production by an Escherichia coli-based whole-cell bioconversion system. Two different approaches, a whole-cell system using M9CA medium and a system using resting cells in buffer, were used for the production of sufficient amounts of metabolites for NMR analysis. Amitriptyline, clomipramine, and imipramine are converted to the corresponding 10-hydroxylated products, whereas the conversion of chlorpromazine and thioridazine leads to a sulfoxidation in position 5. It is shown for the first time that myxobacterial P450s are efficient to produce known human drug metabolites in a milligram scale, revealing their ability to synthesize pharmaceutically important compounds.

Is nuclear factor erythroid 2-related factor 2 responsible for sex differences in susceptibility to acetaminophen-induced hepatotoxicity in mice?

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that positively regulates the expression and activity of cytoprotective genes during periods of oxidative stress. It has previously been shown that some Nrf2 genes are more highly expressed in livers of female than male mice. This could explain previously reported sex-related differences in susceptibility to acetaminophen (APAP) hepatotoxicity in mice, where females show greater resistance to APAP hepatotoxicity. Here, we examined, for the first time, differences in mRNA and protein expression for Nrf2 and a battery of Nrf2-dependent genes in naïve wild-type (WT) and overnight-fasted WT and Nrf2-null male and female mice following APAP treatment. Alanine aminotransferase (ALT) activity was measured as an indicator of hepatotoxicity. Hepatic mRNA and protein levels were measured by quantitative polymerase chain reaction and western blotting, respectively. Contrary to expectations, basal Nrf2 mRNA and protein expression were significantly lower in livers of naïve female than male mice. Although mRNA and/or protein expression of quinone oxidoreductase 1 and multidrug resistance-associated protein 4 was more pronounced in livers of female than male mice under some of the conditions examined, no higher global expression of Nrf2-dependent genes was detected in female mice. Furthermore, ALT activity was significantly elevated in overnight-fasted WT and Nrf2-null male mice following APAP treatment, but no increases in ALT were observed in either genotype of female mice. These results indicate that factors other than Nrf2 are responsible for the lower susceptibility of female mice to APAP hepatotoxicity.

Risk factors for non-adherence to antidepressant treatment in patients with mood disorders

PURPOSE

Adherence to antidepressant therapy by patients with depressive disorders is essential not only to achieve a positive patient outcome but also to prevent a relapse. The aim of this study was to identify potential modelling factors influencing adherence to antidepressant treatment by patients with mood disorders in the community mental health care setting

METHODS

A total of 160 consecutive psychiatric outpatients attending two Community Mental Health Centres on Tenerife Island between September 2011 and May 2012 were asked to participate in the study; of these, 145 accepted. The Morisky self-report scale was used to assess adherence. The potential predictors examined included socio-demographic, clinical and therapeutic variables. The Clinical Global Impression-Severity and -Improvement scales and the Beck Depression Inventory were used for clinical assessment. Drug treatment side-effects were assessed using the "Self-report Antidepressant Side-Effect Checklist." All participants were also asked to complete the "Drug Attitude Inventory" (DAI), "Beliefs about Medicine Questionnaire" (BMQ), and "Leeds Attitude towards concordance Scale". Discriminant analyses were performed to predict non-adherence.

RESULTS

There was no clear correlation between adherence and the socio-demographic variables examined, but adherence was related to a positive attitude of the patients towards his/her treatment (DAI) and low scores in the BMQ-Harm and -Concern subscales. Non-adherence was also related to an increasing severity of depression and to the presence and severity of side-effects.

CONCLUSIONS

Among our study cohort, the profiles of adherent patients to antidepressant treatment were more closely associated with each patient's attitudes and beliefs than to objective socio-demographic variables. The severity of depression played a relevant role in adherence, but whether this role is direct or an interaction with several concurrent factors is not yet clear. Side-effects were also closely related to adherence, as conditioned by frequent polypharmacy.

World Federation of Societies of Biological Psychiatry (WFSBP) guidelines for biological treatment of unipolar depressive disorders, part 1: update 2013 on the acute and continuation treatment of unipolar depressive disorders

OBJECTIVES

This 2013 update of the practice guidelines for the biological treatment of unipolar depressive disorders was developed by an international Task Force of the World Federation of Societies of Biological Psychiatry (WFSBP). The goal has been to systematically review all available evidence pertaining to the treatment of unipolar depressive disorders, and to produce a series of practice recommendations that are clinically and scientifically meaningful based on the available evidence. The guidelines are intended for use by all physicians seeing and treating patients with these conditions.

METHODS

The 2013 update was conducted by a systematic update literature search and appraisal. All recommendations were approved by the Guidelines Task Force.

RESULTS

This first part of the guidelines (Part 1) covers disease definition, classification, epidemiology, and course of unipolar depressive disorders, as well as the management of the acute and continuation phase treatment. It is primarily concerned with the biological treatment (including antidepressants, other psychopharmacological medications, electroconvulsive therapy, light therapy, adjunctive and novel therapeutic strategies) of adults.

CONCLUSIONS

To date, there is a variety of evidence-based antidepressant treatment options available. Nevertheless there is still a substantial proportion of patients not achieving full remission. In addition, somatic and psychiatric comorbidities and other special circumstances need to be more thoroughly investigated. Therefore, further high-quality informative randomized controlled trials are urgently needed.

Psychiatric outpatients' self-reported adherence versus psychiatrists' impressions on adherence in affective disorders

OBJECTIVE

The objective of this study is to explore correlation between patients' self-reported adherence to medication and their treating psychiatrists' impressions on adherence.

METHODS

During a 9-month period, 140 consecutive psychiatric outpatients with affective disorders attending two community mental health centers, and their treating psychiatrists, took part. Data were collected on socio-demographic, clinical, and therapeutic variables. The Clinical Global Impression-Severity and Improvement scales and the Beck Depression Inventory were used for clinical assessment. Adherence was assessed by the psychiatrist's report and the Morisky scale from patients. In addition, "Drug Attitude Inventory," "Beliefs about Medicine Questionnaire," and "Leeds Attitude towards concordance scale" were applied to all participants. A multivariate analysis of variance (Bonferroni control) and a subsequent stepwise regression were performed.

RESULTS

The allocation of patients to "adherent" or "non-adherent" categories by the patients themselves and their treating psychiatrists was divergent in more than 40% of the cases. The best agreement appears when treatment is prolonged. There is a better agreement with patients having a positive view of the medicines. When patients consider the medication harmful, this is when psychiatrists perceive more non-adherence. The agreement is also better in mild cases of depression.

CONCLUSIONS

Adherence was principally compromised by patient-related factors, especially their beliefs and attitudes toward their treatment and its duration.

Sex and gender differences in cardiovascular drug therapy

This chapter outlines sex differences in pharmacokinetics and pharmacodynamics of the most frequently used drugs in cardiovascular diseases, e.g., coronary artery disease, hypertension, heart failure. Retrospective analysis of previously published drug trials revealed marked sex differences in efficacy and adverse effects in a number of cardiovascular drugs. This includes a higher mortality among women taking digoxin for heart failure, more torsade de pointes arrhythmia in QT prolonging drugs and more cough with ACE inhibitors. Trends towards a greater benefit for women and/or female animals have been observed in some studies for endothelin receptor antagonists, the calcium channel blocker amlodipine, the ACE-inhibitor ramipril and the aldosterone antagonist eplerenone. However, reproduction of these results in independent studies and solid statistical evidence is still lacking. Some drugs require a particularly careful dose adaptation in women: the beta-blocker metoprolol, the calcium channel blocker verapamil, loop-, and thiazide diuretics. In conclusion, sex differences in pharmacokinetics and pharmacodynamics have to be taken into account for cardiovascular drug therapy in women.

Clinically important drug-drug interactions in primary care

WHAT IS KNOWN AND OBJECTIVE

Drug-drug interactions (DDIs) cause considerable morbidity and mortality worldwide and may lead to hospital admission. Sophisticated computerized drug information and monitoring systems, more recently established in many of the emerging economies, including Malaysia, are capturing useful information on prescribing. Our aim is to report on an investigation of potentially serious DDIs, using a university primary care-based system capturing prescription records from its primary care services.

METHODS

We retrospectively collected data from two academic years over 20 months from computerized databases at the Universiti Sains Malaysia (USM) from users of the USM primary care services.

RESULTS AND DISCUSSION

Three hundred and eighty-six DDI events were observed in a cohort of 208 exposed patients from a total of 23,733 patients, representing a 2-year period prevalence of 876·4 per 100,000 patients. Of the 208 exposed patients, 138 (66·3%) were exposed to one DDI event, 29 (13·9%) to two DDI events, 15 (7·2%) to three DDI events, 6 (2·9%) to four DDI events and 20 (9·6%) to more than five DDI events. Overall, an increasing mean number of episodes of DDIs was noted among exposed patients within the age category ≥70 years (P=0·01), an increasing trend in the number of medications prescribed (P<0·001) and an increasing trend in the number of long-term therapeutic groups (P<0·001).

WHAT IS NEW AND CONCLUSION

We describe the prevalence of clinically important DDIs in an emerging economy setting and identify the more common potentially serious DDIs. In line with the observations in developed economies, a higher number of episodes of DDIs were seen in patients aged ≥70 years and with more medications prescribed. The easiest method to reduce the frequency of DDIs is to reduce the number of medications prescribed. Therapeutic alternatives should be selected cautiously.

Acute anxiogenic-like effects of selective serotonin reuptake inhibitors are attenuated by the benzodiazepine diazepam in BALB/c mice

Selective serotonin re-uptake inhibitors (SSRIs), which are used commonly to treat anxiety disorders, have characteristic anxiogenic effects following acute administration. Treatment with anxiolytic benzodiazepines (BZs) may reduce these effects, although little is known about potential drug interactions. Our study evaluated acute anxiogenic-like effects of SSRIs, alone and combined with a BZ. Adult male BALB/c mice received fluoxetine (3.0-30.0mg/kg, i.p.) or citalopram (3.0-30.0mg/kg, i.p.) alone or in combination with diazepam (0.3-10.0mg/kg, i.p.), after which they were evaluated with the light/dark and open-field tests for anxiogenesis/anxiolysis. In addition, release of the stress hormone corticosterone was assessed following combined SSRI/BZ administration. In the light/dark and open-field tests, acute SSRIs produced a behavioral profile consistent with anxiogenesis, while diazepam produced an anxiolytic-like profile. Pre-treatment with diazepam (0.3-10mg/kg) reversed the effects of an anxiogenic-like dose of an SSRI (18mg/kg fluoxetine, 30mg/kg citalopram) in both light/dark and open-field tests. Diazepam, fluoxetine or citalopram, and their combination all significantly increased plasma corticosterone levels to the same degree. These findings suggest that a BZ-type drug can attenuate acute anxiogenic-like effects of an SSRI via a mechanism independent of corticosterone regulation.

17β-Estradiol protects against acetaminophen-overdose-induced acute oxidative hepatic damage and increases the survival rate in mice

Acetaminophen overdose causes acute liver injury or even death in both humans and experimental animals. We investigated the effect of 17β-estradiol against acetaminophen-induced acute liver injury and mortality in mice. Male mice were given acetaminophen (p-acetamidophenol; 300 mg/kg; orally) to induce acute liver injury. Acetaminophen significantly increased the levels of aspartate transaminase, alanine transaminase, myeloperoxidase, lipid peroxidation, and glutathione reductase, but it decreased superoxide dismutase, catalase, and glutathione. In addition, acetaminophen-induced mortality began 4h post-treatment, and all mice died within 9h. 17β-Estradiol (200 μg/kg; i.p.) protected against acetaminophen-induced oxidative hepatic damage by inhibiting neutrophil infiltration and stimulating the antioxidant defense system. However, 17β-estradiol did not affect acetaminophen-induced glutathione depletion or increased glutathione reductase activity. We conclude that 17β-estradiol specifically attenuates acute hepatic damage and decreases mortality in acetaminophen-overdosed male mice.

Clinically based evidence of drug-herb interactions: a systematic review

IMPORTANCE OF THE FIELD

Healthcare practitioners are deeply concerned about drug-herb interactions and how concurrent administration may affect both the safety and effectiveness of prescribed drugs. Interactions between botanical medicines and synthetic drugs can be clinically relevant and it is important to understand what kinds of interactions are possible. Better knowledge in this area will help avoid negative interactions and may also help enable synergistic interactions.

AREAS COVERED IN THIS REVIEW

Includes articles related to the investigation of Western botanicals or whole herbal extracts in human subjects, investigating either the impact on Cytochrome P450 isoenzymes or an assessment of specific drug-herb interactions within a clinical trial. Searches were conducted in both Pubmed and EMBASE from inception to March 2009.

WHAT THE READER WILL GAIN

Knowledge regarding specific interactions to consider in clinical practice. The reader will also gain an appreciation of the complexities associated with the area of drug-herb interactions. Summary tables of relevant drug-herb interactions are presented both for the individual herbs included and at the level of the CYP450 enzymes.

TAKE HOME MESSAGE

Knowledge of drug-herb interactions is limited and much more research needs to be done to further document clinically relevant interactions. Even though preclinical data are often poorly generalizable to the human situation, caution must be taken in the absence of clinical evidence especially where drugs with narrow therapeutic windows are concerned.

Azoles and antidepressants: a mini-review of the tolerability of co-administration

Depression is a common condition in chronically ill immunosuppressed patients on long-term antifungal therapy with azoles. As both azoles and more recent antifungals are metabolised by the P450 enzymatic system in the liver, here we review the potential of clinically meaningful interactions between antidepressants and azoles. Selective serotonin reuptake inhibitors are safer compared to tricycle antidepressants when co-administered with azoles. More pharmacovigilance is needed.

Genetic underpinnings of tardive dyskinesia: passing the baton to pharmacogenetics

Manifestation of tardive dyskinesia (TD) among schizophrenia subjects on long-term antipsychotic treatment with typical drugs has been a clinical concern. Despite its association with extrapyramidal symptoms, typical drugs are still routinely prescribed globally though marginally superior atypical drugs have long been available. The genetic component in the etiology of TD is well documented. Search for these determinants has led to a few consensus associations of CYP2D6 *10, CYP1A2*1F, DRD2 Taq1A (rs1800497), DRD3 Ser9Gly (rs6280) and MnSOD Ala9Val (rs4880) variants with TD. However, translation of these observations into the clinic has not been achieved so far. This review discusses the salient features of TD etiopathology, current status of TD genetics, interactions between genetic and nongenetic factors, some major drawbacks, challenges and expected focus in TD research over the next decade, with emphasis on pharmacogenetics.

Association Between Selective Serotonin-Reuptake Inhibitors, Second-Generation Antipsychotics, and Neuroleptic Malignant Syndrome

Objective

To review the published reports of neuroleptic malignant syndrome (NMS) associated with the use of selective serotonin-reuptake inhibitors (SSRIs) and second-generation antipsychotics.

Data Source:

Information was selected from a MEDLINE search of English-language literature (1950–May 2008). Manual search of all published cases indexed in MEDLINE (English language only) of NMS associated with second-generation antipsychotics was also performed.

Study Selection And Data Extraction:

Pertinent information from all reports obtained was included, with specific emphasis on patient age, sex, second-generation antipsychotic involved, SSRI or other antidepressant involved, time of onset of NMS symptoms in relation to medication changes, treatment administered, and outcome of the reaction.

Data Synthesis:

NMS has been reported with every second-generation antipsychotic agent. It is unclear whether concomitant therapy with other agents may increase the risk of NMS development via pharmacodynamic or pharmacokinetic mechanisms or both, The suggested pharmacodynamic mechanism for increased risk of NMS with concomitant use of SSRIs is the effect of serotonin on dopamine release. Serotonin further inhibits dopamine release and thereby may worsen a hypodopaminergic state induced by antipsychotics. Pharmacokinetic factors may also play a role in some NMS cases involving an SSRI by increasing antipsychotic concentrations. An examination of case reports seems to indícale that at least in some casos, a temporal relationship exists with the addition of an SSRI to existing antipsychotic therapy.

Conclusions:

The use of SSRIs may be associated with an increased risk of NMS development in (hose receiving second-generation antipsychotics. Clinicians should closely monitor patients for the potential development of NMS.

Drug-associated disease: cytochrome P450 interactions

Critically ill patients generally are older, frequently have organ failure, and commonly receive multiple medications, all of which make them susceptible to adverse effects of drugs. Drug interactions are a common adverse effect, and many are predictable based on understanding the mechanisms that underlie drug interactions. This article identifies commonly used medications in critically ill patients and the associated drug interactions that may occur with emphasis on the cytochrome P450 enzyme system.

Effects of cytochrome P450 3A modulators ketoconazole and carbamazepine on quetiapine pharmacokinetics

AIMS

To explore the potential for drug interactions on quetiapine pharmacokinetics using in vitro and in vivo assessments.

METHODS

The CYP enzymes responsible for quetiapine metabolite formation were assessed using recombinant expressed CYPs and CYP-selective inhibitors. P-glycoprotein (Pgp) transport was tested in MDCK cells expressing the human MDR1 gene. The effects of CYP3A4 inhibition were evaluated clinically in 12 healthy volunteers that received 25 mg quetiapine before and after 4 days of treatment with ketoconazole 200 mg daily. To assess CYP3A4 induction in vivo, 18 patients with psychiatric disorders were titrated to steady-state quetiapine levels (300 mg twice daily), then titrated to 600 mg daily carbamazepine for 2 weeks.

RESULTS

CYP3A4 was found to be responsible for formation of quetiapine sulfoxide and N- and O-desalkylquetiapine and not a Pgp substrate. In the clinical studies, ketoconazole increased mean quetiapine plasma C(max) by 3.35-fold, from 45 to 150 ng ml(-1) (mean C(max) ratio 90% CI 2.51, 4.47) and decreased its clearance (Cl/F) by 84%, from 138 to 22 l h(-1) (mean ratio 90% CI 0.13, 0.20). Carbamazepine decreased quetiapine plasma C(max) by 80%, from 1042 to 205 ng ml(-1) (mean C(max) ratio 90% CI 0.14, 0.28) and increased its clearance 7.5-fold, from 65 to 483 l h(-1) (mean ratio 90% CI 6.04, 9.28).

CONCLUSIONS

Cytochrome P450 3A4 is a primary enzyme responsible for the metabolic clearance of quetiapine. Quetiapine pharmacokinetics were affected by concomitant administration of ketoconazole and carbamazepine, and therefore other drugs and ingested natural products that strongly modulate the activity or expression of CYP3A4 would be predicted to change exposure to quetiapine.

Acetaminophen metabolism does not contribute to gender difference in its hepatotoxicity in mouse

Gender is an important factor in pharmacokinetics and pharmacodynamics. In the current study, gender difference in acetaminophen (APAP)-induced hepatotoxicity has been examined. Male and female mice were injected with a toxic dose of APAP (500 mg/kg, ip). Female mice were resistant to the hepatotoxic effects of APAP, depicted by serum alanine aminotransferase and sorbital dehydrogenase activities and histological analysis. Basal hepatic reduced glutathione (GSH) levels were lower in females than in males, suggesting that basal GSH level may not be a factor in determining the gender difference of APAP hepatotoxicity. APAP metabolism was slower in females than males, revealed by lower levels of glucuronidation and sulfation and higher amounts of free APAP in the livers of female mice. Lower basal Cyp1a2 mRNA levels and lower expression of Cyp1a2 and Cyp3a11 mRNAs after APAP dosing were also observed in females compared with males. However, there was no gender difference in N-acetyl-p-benzoquinone imine covalent binding 2 h after APAP administration, suggesting similar APAP bioactivation between genders. Moreover, liver Gst pi mRNA levels were significantly lower in females than males. This finding is consistent with a previous report, which showed that Gst pi knockout mice are protected from APAP-induced liver toxicity. In conclusion, gender difference of APAP-induced hepatotoxicity is not likely due to APAP metabolism. Perhaps, it is in part due to gender-dependent Gst pi expression. However, the mechanism underlying the association between reduction in Gst pi expression and hepatoprotective effect against APAP toxicity remains to be further explored.

Rates of In Vivo Methylation of Desipramine and Nortriptyline

Routine monitoring of an 81-year-old man receiving treatment with nortriptyline for generalized anxiety disorder and depression revealed plasma concentrations of both amitriptyline and nortriptyline. In humans, the tricyclic antidepressant (TCA) tertiary amines imipramine and amitriptyline are typically metabolized by demethylation to the secondary active metabolites desipramine and nortriptyline, respectively. However, to our knowledge, methylation of secondary amine TCAs has been reported in only one case report of nortriptyline overdose and in two studies involving desipramine. In a retrospective analysis of patients from five Veterans Affairs medical centers, the rate of methylation of desipramine and nortriptyline was 8.9 % (five of 56 patients) and 14.6% (36 of 247), respectively. Possible explanations for methylation include genetic polymorphisms in cytochrome P450 metabolizing enzymes, polymorphism of amine N-methyltransferase enzyme, drug-drug interactions, smoking, and alcohol consumption. However, the mechanism by which methylation occurs is unclear and warrants further investigation. Awareness of the phenomenon could help in discouraging repeated laboratory tests and unnecessary adjustments of drug therapies, resulting in cost savings and better patient outcomes.

Systematic overview of drug interactions with antidepressant medications

OBJECTIVE

Antidepressants are commonly used drugs with potential for numerous drug interactions. This study aims to systematically review the literature on drug interactions with antidepressants.

METHODS

We searched MEDLINE (1966 to November 2003) and EMBASE (1980 to 2003), using the heading drug interactions combined with individual antidepressant names. We restricted searches to English-language articles and human studies. We screened drug interaction texts and review articles for relevant studies. We included articles reporting original human data on drug interactions with antidepressants commonly used in North America. Articles were independently evaluated by 2 reviewers on clinical effect, clinical significance, and quality of evidence. Discrepancies were resolved by consensus.

RESULTS

There were 904 eligible interactions, involving 9509 patients, for a total of 598 summary interactions. Of these, 439 (73%) demonstrated an interaction, 148 (25%) had no effect, and 11 (2%) had conflicting evidence. For 510 interactions (85%), the quality of evidence was poor. It was fair for 67 (11%) interactions and good for 10 (2%) interactions. There were no interactions with excellent quality of evidence. There were 145 (24%) interactions of major clinical significance. These were predominantly hypertensive emergencies and serotonin syndrome. Most interacting drugs had central nervous system (CNS) activity. As expected, monoamine oxidase inhibitors (MAOIs) appear to be the most problematic family in terms of potential for serious drug interactions.

CONCLUSIONS

Drug interactions with antidepressants are an important cause for concern, but this concern is based primarily on poor evidence. We recommend caution when combining antidepressants with other CNS drugs, particularly when coadministering MAOIs with other substances.

Psychotropic drug interactions with valproate

Valproate is a well-established anticonvulsant that is increasingly being employed, often in combination with other psychotropics, for its mood-stabilizing properties. This compound is metabolized by conjugation, beta-oxidation, and cytochrome P450 oxidation (CYP2C9, CYP2C19, and CYP2A6) and also acts as a broad-spectrum inhibitor of a variety of hepatic enzymes including glucoronyltransferase, epoxide hydrolase, and the CYP2C enzymes. In addition, it exhibits saturable protein binding and competes with many drugs for protein binding sites. It is therefore not surprising that valproate has been noted to interact with psychotropic medications of all classes. This article provides an overview of the noted pharmacokinetic psychotropic interactions with valproate, with a particular focus on the mechanisms of these interactions and potential clinical consequences.

Polypharmacy in psychiatric practice in the Canary Islands

BACKGROUND

Polypharmacy with psychoactive drugs is an increasingly common and debatable contemporary practice in clinical psychiatry based more upon experience than evidence. The objective of this study was to evaluate the prevalence and conditioners of polypharmacy in psychiatric patients.

METHOD

A cross-sectional survey was carried out using the Canary Islands Health Service Clinical Records Database. A representative sample (n = 2,647) of patients with mental disorders receiving psychotropic medication was studied.

RESULTS

The mean number of psychoactive drugs prescribed was 1.63 +/- 0.93 (range 1-7). The rate of polypharmacy was 41.9%, with 27.8% of patients receiving two drugs, 9.1% receiving three, 3.2% receiving four, and 1.8% of the patients receiving five or more psychotropic drugs. Multiple regression analysis shows that variables sex and diagnosis have a predictive value with regard to the number of psychotropic drug used, being men and schizophrenic patients the most predisposed. Benzodiazepines were the more prevalent drugs in monotherapy, while anticonvulsants and antipsychotics were the more used in combination with other treatment. A questionable very high degree of same-class polypharmacy was evidenced, while multi-class, adjunctive and augmentation polypharmacy seem to be more appropriate.

CONCLUSIONS

Almost half of the psychiatric patients are treated with several psychotropics. Polypharmacy is common and seems to be problematic, especially when same class of drugs are prescribed together. Some diagnoses, such as schizophrenia, are associated with an increase risk of Polypharmacy but there is a lack of evidence based indicators that allows for quality evaluation on this practice.

Pharmacokinetic Factors in the Adverse Cardiovascular Effects of Antipsychotic Drugs

Antipsychotics may cause serious adverse cardiovascular effects, including prolonged QT interval and sudden death. This review considers antipsychotic-induced cardiovascular events from three perspectives: high-risk drugs, high-risk individuals and high-risk drug interactions. Pharmacokinetic drug interactions involving the cytochrome P450 (CYP) enzymatic pathway and pharmacodynamic interactions leading to direct cardiotoxic effects are discussed. Original reports on antipsychotic-induced drug interactions are reviewed, with consideration of management guidelines. The literature was reviewed from 1 January 1966 to 1 February 2002. The literature search revealed only 12 original articles published on antipsychotic drug interactions leading to cardiovascular adverse events. Only 4 of the 12 reports were prospective studies; the remainder were either retrospective or anecdotal.Although poor study designs preclude a definitive statement, it appears that pharmacokinetic interactions primarily involved the CYP2D6 and CYP3A4 enzymatic pathways. Those involving the CYP2D6 isozyme included interactions with tricyclic antidepressants, selective serotonergic reuptake inhibitors and beta-blockers. Among these drug interactions, tricyclic antidepressants were most likely to reach clinical significance because of their limited therapeutic index. Drug interactions related to the CYP3A4 pathway were generally less severe, and involved high-potency antipsychotics coadministered with inhibitors such as clarithromycin. Strategies are discussed for the management of adverse cardiovascular events related to antipsychotic drug interactions, including the use of an algorithm. Large, randomised, placebo-controlled studies with strict inclusion criteria are needed to determine the role that antipsychotics play in QT prolongation and sudden death.

Oral antifungal drug interactions: a mechanistic approach to understanding their cause

Oral antifungal drugs are generally regarded as effective and safe when used according to their manufacturer's recommendation. However, when an oral antifungal agent is administered with certain interacting agents or classes of drugs, rare severe iatrogenic adverse experiences including death may occur. This article alerts and demystifies some of the clinically significant oral antifungal drug interactions by exploring their underlying pharmacological basis.

Toxicological interactions involving psychiatric drugs and alcohol: an update

This review focuses on the toxicological interactions between alcohol (ethanol) and psychiatric drugs (antidepressants and antipsychotics), including those leading to fatal poisoning. Acute or chronic ingestion of alcohol when combined with psychiatric drugs may lead to several clinically significant toxicological interactions. The metabolism of these drugs is generally but not always delayed by acute alcohol ingestion. Drugs undergoing metabolism may also show increased metabolic clearance with chronic alcohol ingestion. Therefore, the net effect may be influenced by internal (e.g. disease, age, gender), external (e.g. environment, diet) and pharmacokinetic (e.g. dose, timing of ingestion, gastrointestinal absorption, distribution and elimination) factors. Cases of fatal poisoning involving coadministration of psychiatric drugs, alcohol and other drugs prompted this review.

Mechanisms of clinically relevant drug interactions associated with tacrolimus

The clinical management of tacrolimus, a macrolide used as immunosuppressant after transplantation, is complicated by its narrow therapeutic index in combination with inter- and intraindividually variable pharmacokinetics. As a substrate of cytochrome P450 (CYP) 3A enzymes and P-glycoprotein, tacrolimus interacts with several other drugs used in transplantation medicine, which also are known CYP3A and/or P-glycoprotein inhibitors and/or inducers. In clinical studies, CYP3A/P-glycoprotein inhibitors and inducers primarily affect oral bioavailability of tacrolimus rather than its clearance, indicating a key role of intestinal P-glycoprotein and CYP3A. There is an almost complete overlap between the reported clinical drug interactions of tacrolimus and those of cyclosporin. However, in comparison with cyclosporin, only few controlled drug interaction studies have been carried out, but tacrolimus drug interactions have been extensively studied in vitro. These results are inconsistent and are of poor predictive value for clinical drug interactions because of false negative results. P-glycoprotein regulates distribution of tacrolimus through the blood-brain barrier into the brain as well as distribution into lymphocytes. Interaction of other drugs with P-glycoprotein may change tacrolimus tissue distribution and modify its toxicity and immunosuppressive activity. There is evidence that ethnic and gender differences exist for tacrolimus drug interactions. Therapeutic drug monitoring to guide dosage adjustments of tacrolimus is an efficient tool to manage drug interactions. In the near future, progress can be expected from studies evaluating potential pharmacokinetic interactions caused by herbal preparations and food components, the exact biochemical mechanism underlying tacrolimus toxicity, and the potential of inhibition of CYP3A and P-glycoprotein to improve oral bioavailability and to decrease intraindividual variability of tacrolimus pharmacokinetics.

Inhibitory effects of tricyclic antidepressants (TCAs) on human cytochrome P450 enzymes in vitro: mechanism of drug interaction between TCAs and phenytoin

The ability of tricyclic antidepressants (TCAs) to inhibit phenytoin p-hydroxylation was evaluated in vitro by incubation studies of human liver microsomes and cDNA-expressed cytochrome p450s (p450s). The TCAs tested were amitriptyline, imipramine, nortriptyline, and desipramine. Amitriptyline and imipramine strongly and competitively inhibited phenytoin p-hydroxylation in microsomal incubations (estimated K(i) values of 5.2 and 15.5 micro M, respectively). In contrast, nortriptyline and desipramine produced only weak inhibition. In the incubation study using cDNA-expressed P450s, both CYP2C9 and CYP2C19 catalyzed phenytoin p-hydroxylation, whereas TCAs inhibited only the CYP2C19 pathway. All of the TCAs tested inhibited CYP2D6-catalyzed dextromethorphan-O-demethylation competitively, with estimated K(i) values of 31.0, 28.6, 7.9, and 12.5 micro M, respectively. The tertiary amine TCAs, amitriptyline and imipramine, also inhibited CYP2C19-catalyzed S-mephenytoin 4'-hydroxylation (estimated K(i) of 37.7 and 56.8 micro M, respectively). The secondary amine TCAs, nortriptyline and desipramine, however, showed minimal inhibition of CYP2C19 (estimated IC(50) of 600 and 685 micro M, respectively). None of the TCAs tested produced remarkable inhibition of any other p450 isoforms. These results suggest that TCAs inhibit both CYP2D6 and CYP2C19 and that the interaction between TCAs and phenytoin involves inhibition of CYP2C19-catalyzed phenytoin p-hydroxylation.

Pharmacogenetics for the individualization of psychiatric treatment

Drug treatment of psychiatric disorders is troubled by severe adverse effects, low compliance and lack of efficacy in about 30% of patients. Pharmacogenetic research in psychiatry aims to elucidate the reasons for treatment failure and adverse reactions. Genetic variations in cytochrome P450 (CYP) enzymes have the potential to directly influence the efficacy and tolerability of commonly used antipsychotic and antidepressant drugs. The activity of psychiatric drugs can also be influenced by genetic alterations affecting the drug target molecule. These include the dopaminergic and serotonergic receptors, neurotransmitter transporters and other receptors and enzymes involved in psychiatric disorders. Association studies investigating the relation between genetic polymorphisms in metabolic enzymes and neurotransmitter receptors on psychiatric treatment outcome provide a step towards the individualization of psychiatric treatment through enabling the selection of the most beneficial drug according to the individual's genetic background.

5-HT3-receptor antagonists and the cytochrome P450 system: clinical implications

Many patients with cancer receive multiple chemotherapy agents as well as other medications for coexisting medical conditions. Despite the introduction of 5-HT3 receptor antagonists, the management of nausea and vomiting following cancer treatment and after cancer surgery remains complex, particularly when patients are receiving multiple prescription medications. As a drug class, the 5-HT3 receptor antagonists have good antiemetic efficacy and an improved safety profile over conventional antiemetics. Nevertheless, pharmacologic differences exist between these agents, such as their interaction with the metabolic cytochrome P450 system. This review examines the major metabolic differences between the most frequently prescribed 5-HT3 receptor antagonists, dolasetron, granisetron, ondansetron, and tropisetron. The potential drug interactions that these differences may precipitate and key genetic interindividual variations in drug metabolism are also considered. To avoid or minimize potential drug interactions, the 5-HT3 receptor antagonist with the lowest risk of these interactions should be considered as first choice.

Prevalence and patterns of concomitant use of selective serotonin reuptake inhibitors and other antidepressants in a high-cost polypharmacy cohort

BACKGROUND

Concomitant antidepressant therapy for patients who do not respond to selective serotonin reuptake inhibitors (SSRIs) may be appropriate under close medical supervision. However, little is known about the prevalence or patterns of concurrent antidepressant therapy in a typical large health maintenance organization.

OBJECTIVE

The purpose of this study was to determine the prevalence of concomitant SSRI-antidepressant therapy and to assess the relationship between concomitant SSRI therapy, patient demographic characteristics, and the use of multiple prescribers and pharmacies.

METHODS

This was a retrospective analysis of administrative prescription and medical claims data from January 1998 through September 1999. Data were obtained on beneficiaries who had >15 prescriptions dispensed in either of the first 2 quarters of 1999 and/or patients who accrued >$1,000 in prescription costs in either or both of the quarters. Patients were defined as undergoing concomitant SSRI therapy if they had received > or = 14 days of concomitant treatment with 2 SSRIs, an SSRI and tricyclic antidepressant, an SSRI and benzodiazepine, or an SSRI and miscellaneous antidepressant. Contingency analysis and logistic regression were used to identify factors associated with concomitant SSRI therapy.

RESULTS

The relative risk for concomitant SSRI-SSRI therapy for patients with multiple prescribers versus a single prescriber was 2.32; the relative risk for patients receiving prescriptions from multiple pharmacies versus a single pharmacy was 2.97. Female patients were 19.8% more likely than male patients to receive concomitant SSRI therapy. Use of multiple prescribers increased the odds for concomitant SSRI therapy by >3.0 across the 4 therapeutic combinations. Use of multiple pharmacies increased the odds for concomitant SSRI-SSRI therapy by 5.42.

CONCLUSIONS

Prescription of concomitant SSRI therapy was strongly associated with changes in strength of dosage and products and with use of multiple prescribers and pharmacies.

World Federation of Societies of Biological Psychiatry (WFSBP) Guidelines for Biological Treatment of Unipolar Depressive Disorders, Part 1: Acute and continuation treatment of major depressive disorder

These practice guidelines for the biological treatment of unipolar depressive disorders were developed by an international Task Force of the World Federation of Societies of Biological Psychiatry (WFSBP). The goal for developing these guidelines was to systematically review all available evidence pertaining to the treatment of unipolar depressive disorders, and to produce a series of practice recommendations that are clinically and scientifically meaningful based on the available evidence. These guidelines are intended for use by all physicians seeing and treating patients with these conditions. The data used for developing these guidelines have been extracted primarily from various national treatment guidelines and panels for depressive disorders, as well as from meta-analyses and reviews on the efficacy of antidepressant medications and other biological treatment interventions identified by a search of the MEDLINE database and Cochrane Library. The identified literature was evaluated with respect to the strength of evidence for its efficacy and was then categorized into four levels of evidence (A-D). This first part of the guidelines covers disease definition, classification, epidemiology and course of unipolar depressive disorders, as well as the management of the acute and continuation-phase treatment. These guidelines are primarily concerned with the biological treatment (including antidepressants, other psychopharmacological and hormonal medications, electroconvulsive therapy, light therapy, adjunctive and novel therapeutic strategies) of young adults and also, albeit to a lesser extent, children, adolescents and older adults.

The pharmacology and toxicology of atypical antipsychotic agents

Recently, atypical antipsychotic agents have largely replaced traditional agents as first-line drugs for the treatment of schizophrenia. It is likely that atypical agents will soon account for the majority of poisonings from antipsychotic agents that present to health care facilities in the US. This article reviews the pharmacodynamics, pharmacokinetics, and toxicology of atypical antipsychotic drugs, chiefly clozapine, risperidone, olanzapine, and quetiapine. A descriptive summary of the human overdose experience with these agents is provided. Adverse effect and drug interaction data are reviewed. Based on the available pharmacodynamic, pharmacokinetic, and human overdose data, recommendations on management are provided.

Neurotropic and psychotropic drugs in dermatology

Several psychotropic and neurotropic agents are useful in treating patients with skin diseases such as obsessive compulsive skin manipulation, delusions of parasitosis, generalized pruritus, and post-herpetic neuralgia. The mechanism of action of these agents is based on their interaction with central and peripheral neuronal receptors. The medications discussed in this article include the tricyclic antidepressants, serotonin reuptake inhibitors, naltrexone, pimozide, and gabapentin. The pharmacology, mechanism of action, adverse effects, drug interactions, and monitoring guidelines are outlined for each of these drugs.

Biotransformation of post-clozapine antipsychotics: pharmacological implications

The need to develop new antipsychotics that have fewer motor adverse effects and offer better treatment of negative symptoms has led to a new generation of drugs. Most of these drugs undergo extensive first-pass metabolism and are cleared almost exclusively by metabolism, except for amisulpride whose clearance is largely due to urinary excretion. Risperidone has metabolic routes in common with ziprasidone but shows differences in regard to other main pathways: the benzisoxazole moiety of risperidone is oxidised by cytochrome P450 (CYP) 2D6 to the active 9-hydroxyrisperidone, whereas the benzisothiazole of ziprasidone is primarily oxidised by CYP3A4, yielding sulfoxide and sulfone derivatives with low affinity for target receptors in vitro. Olanzapine, quetiapine and zotepine also have some common metabolic features. However, for the thienobenzodiazepine olanzapine a main metabolic route is direct conjugation at the benzodiazepine nucleus, whereas for the dibenzothiazepine quetiapine and the dibenzothiepine zotepine it is CYP3A4-mediated oxidation, leading to sulfoxidation, hydroxylation and dealkylation for quetiapine, but N-demethylation to the active nor-derivative for zotepine. Although the promising benzisoxazole (iloperidone) and benzisothiazole (perospirone) antipsychotics share some metabolic routes with the structurally related available drugs, they too have pharmacologically relevant compound-specific pathways. For some of the new antipsychotics we know the isoenzymes involved in their main metabolic pathways and the endogenous and exogenous factors that, by affecting enzyme activity, can potentially modify steady-state concentrations of the parent drug or its metabolite(s), but we know very little about others (e.g. amisulpride isomers, nemonapride). For yet others, information is scarce about the activity of the main metabolites and whether and how these contribute to the effect of the parent drug. Aging reduces the clearance of most antipsychotics, except amisulpride (which requires further evaluation) and ziprasidone. Liver impairment has little or no effect on the pharmacokinetics of olanzapine, quetiapine, risperidone (and 9-hydroxy-risperidone) and ziprasidone, but information is lacking for amisulpride. Renal impairment significantly reduces the clearance and prolongs the elimination half-life of amisulpride and risperidone. Again, studies are still not available for some drugs (zotepine) and have focused on the parent drug for others (olanzapine, quetiapine, ziprasidone) despite the fact that renal impairment would be expected to lower the clearance of more polar metabolites. Addressing these issues may assist clinicians in the design of safe and effective regimens for this group of drugs, and in selecting the best agent for each specific population.

Pharmacogenomics: the promise of personalized medicine

Pharmacogenetics and pharmacogenomics deal with the genetic basis underlying variable drug response in individual patients. The traditional pharmacogenetic approach relies on studying sequence variations in candidate genes suspected of affecting drug response. On the other hand, pharmacogenomic studies encompass the sum of all genes, i.e., the genome. Numerous genes may play a role in drug response and toxicity, introducing a daunting level of complexity into the search for candidate genes. The high speed and specificity associated with newly emerging genomic technologies enable the search for relevant genes and their variants to include the entire genome. These new technologies have essentially spawned a new discipline, termed pharmacogenomics, which seeks to identify the variant genes affecting the response to drugs in individual patients. Moreover, pharmacogenomic analysis can identify disease susceptibility genes representing potential new drug targets. All of this will lead to novel approaches in drug discovery, an individualized application of drug therapy, and new insights into disease prevention. Current concepts in drug therapy often attempt treatment of large patient populations as groups, irrespective of the potential for individual, genetically-based differences in drug response. In contrast, pharmacogenomics may help focus effective therapy on smaller patient subpopulations which although demonstrating the same disease phenotype are characterized by distinct genetic profiles. Whether and to what extent this individual, genetics-based approach to medicine results in improved, economically feasible therapy remain to be seen. To exploit these opportunities in genetic medicine, novel technologies will be needed, legal and ethical questions must be clarified, health care professionals must be educated, and the public must be informed about the implications of genetic testing in drug therapy and disease management.

Gender-related differences in pharmacokinetics and their clinical significance

In this review I have attempted to summarize gender differences in pharmacokinetics involving the cytochrome P450 (CYP) isozymes of young and mature adults, excluding the effects of the menstrual cycle, use of oral contraceptives and pregnancy. Sex differences in drug metabolism and elimination are mainly related to steroid hormone levels. CYP3A4, responsible for the metabolism of over 50% of therapeutic drugs, exhibits higher activity in women than in men. Nonetheless, the absence of a sex difference has been reported by some workers. The activity of several other CYP (CYP2C19, CYP2D6, CYP2E1) isozymes and the conjugation (glucuronidation) activity involved in drug metabolism may be higher in men than in women. Drug metabolism in women is affected by sex-specific factors (menopause, pregnancy and menstruation) in addition to the cigarette smoking, drug ingestion and alcohol consumption that are more commonly observed factors in men. Furthermore, they are affected by physiological factors such as drug absorption, protein binding and elimination. Thus, careful attention should be paid to the side-effects and toxicity arising from sex differences in drug metabolism in clinical situations. Although there are specific ethical considerations regarding carrying out drug trials in women, the relationship between the side-effects and toxicity that may be influenced by hormones during drug metabolism and drug treatment needs further study.