Venlafaxine oxidation in vitro is catalysed by CYP2D6

Venlafaxine exposure alters mitochondrial respiration and mitomiR abundance in zebrafish brains

Wastewater treatment plant (WWTP) effluent often releases pharmaceuticals like venlafaxine (a serotonin-norephinephrine reuptake inhibitor antidepressant) to freshwater ecosystems at levels causing adverse metabolic effects on fish. Changes to fish metabolism can be regulated by epigenetic mechanisms like microRNA (small RNA molecules that regulate mRNA translation), including regulating mitochondrial mRNAs. Nuclear-encoded microRNAs regulate mitochondrial gene expression in mammals, and have predicted effects in fish. We aimed to identify whether venlafaxine exposure changed mitochondrial respiration and resulted in differentially abundant mitochondrial microRNA (mitomiRs) in zebrafish brains. In vitro exposure of brain homogenate to below environmentally relevant concentrations of venlafaxine (<1 µg/L) caused a decrease in mitochondrial respiration, although this was not driven by changes to mitochondrial Complex I or II function. To identify whether these effects occur in vivo, zebrafish were exposed to 1 µg/L venlafaxine for 0, 1, 6, 12, 24, and 96 h. In vivo, venlafaxine exposure had no significant effects on brain mitochondrial respiration; however, select mitomiRs (dre-miR-301a-5p, dre-miR-301b-3p, and dre-miR-301c-3p) were also measured, because they were bioinformatically predicted to regulate mitochondrial cytochrome c oxidase subunit I (COI) abundance. These mitomiRs were differentially regulated based on venlafaxine exposure (with miR-301c-3p abundance differing during the day and miR-301b-3p being lower in exposed fish at night), and with respect to sex and time sampled. Overall, the results demonstrated that in vitro venlafaxine exposure to zebrafish brain caused a decrease in mitochondrial respiration, but these effects were not seen after acute in vivo exposure. Results may have differed because in vivo exposure allows for fish to mitigate effects through mechanisms that could include mitomiR regulation, and because fish were only acutely exposed. Environ Toxicol Chem 2024;43:1569-1582. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

PBPK modeling to predict the pharmacokinetics of venlafaxine and its active metabolite in different CYP2D6 genotypes and drug-drug interactions with clarithromycin and paroxetine

Venlafaxine, a serotonin-norepinephrine reuptake inhibitor (SNRI), is indicated for the treatment of major depressive disorder, social anxiety disorder, generalized anxiety disorder, and panic disorder. Venlafaxine is metabolized to the active metabolite desvenlafaxine mainly by CYP2D6. Genetic polymorphism of CYP2D6 and coadministration with other medications can significantly affect the pharmacokinetics and/or pharmacodynamics of venlafaxine and its active metabolite. This study aimed to establish the PBPK models of venlafaxine and its active metabolite related to CYP2D6 genetic polymorphism and to predict drug-drug interactions (DDIs) with clarithromycin and paroxetine in different CYP2D6 genotypes. Clinical pharmacogenomic data for venlafaxine and desvenlafaxine were collected to build the PBPK model. Physicochemical and absorption, distribution, metabolism, and excretion (ADME) characteristics of respective compounds were obtained from previously reported data, predicted by the PK-Sim® software, or optimized to capture the plasma concentration-time profiles. Model evaluation was performed by comparing the predicted pharmacokinetic parameters and plasma concentration-time profiles to the observed data. Predicted plasma concentration-time profiles of venlafaxine and its active metabolite were visually similar to the observed profiles and all predicted AUC and Cmax values for respective compounds were included in the twofold error range of observed values in non-genotyped populations and different CYP2D6 genotypes. When clarithromycin or clarithromycin plus paroxetine was concomitantly administered, predicted plasma concentration-time profiles of venlafaxine properly captured the observed profiles in two different CYP2D6 genotypes and all predicted DDI ratios for AUC and Cmax were included within the acceptance range. Consequently, the present model successfully captured the pharmacokinetic alterations of venlafaxine and its active metabolite according to CYP2D6 genetic polymorphism as well as the DDIs between venlafaxine and two CYP inhibitors. The present model can be used to predict the pharmacokinetics of venlafaxine and its active metabolite considering different races, ages, coadministered drugs, and CYP2D6 activity of individuals and it can contribute to individualized pharmacotherapy of venlafaxine.

Venlafaxine's therapeutic reference range in the treatment of depression revised: a systematic review and meta-analysis

INTRODUCTION

The selective serotonin and norepinephrine reuptake inhibitor venlafaxine is among the most prescribed antidepressant drugs worldwide and, according to guidelines, its dose titration should be guided by drug-level monitoring of its active moiety (AM) which consists of venlafaxine (VEN) plus active metabolite O-desmethylvenlafaxine (ODV). This indication of therapeutic drug monitoring (TDM), however, assumes a clear concentration/effect relationship for a drug, which for VEN has not been systematically explored yet.

OBJECTIVES

We performed a systematic review and meta-analysis to investigate the relationship between blood levels, efficacy, and adverse reactions in order to suggest an optimal target concentration range for VEN oral formulations for the treatment of depression.

METHODS

Four databases (MEDLINE (PubMed), PsycINFO, Web of Science Core Collection, and Cochrane Library) were systematically searched in March 2022 for relevant articles according to a previously published protocol. Reviewers independently screened references and performed data extraction and critical appraisal.

RESULTS

High-quality randomized controlled trials investigating concentration/efficacy relationships and studies using a placebo lead-in phase were not found. Sixty-eight articles, consisting mostly of naturalistic TDM studies or small noncontrolled studies, met the eligibility criteria. Of them, five cohort studies reported a positive correlation between blood levels and antidepressant effects after VEN treatment. Our meta-analyses showed (i) higher AM and (ii) higher ODV concentrations in patients responding to VEN treatment when compared to non-responders (n = 360, k = 5). AM concentration-dependent occurrence of tremor was reported in one study. We found a linear relationship between daily dose and AM concentration within guideline recommended doses (75-225 mg/day). The population-based concentration ranges (25-75% interquartile) among 11 studies (n = 3200) using flexible dosing were (i) 225-450 ng/ml for the AM and (ii) 144-302 ng/ml for ODV. One PET study reported an occupancy of 80% serotonin transporters for ODV serum levels above 85 ng/ml. Based on our findings, we propose a therapeutic reference range for AM of 140-600 ng/ml.

CONCLUSION

VEN TDM within a range of 140 to 600 ng/ml (AM) will increase the probability of response in nonresponders. A titration within the proposed reference range is recommended in case of non-response at lower drug concentrations as a consequence of VEN's dual mechanism of action via combined serotonin and norepinephrine reuptake inhibition. Drug titration towards higher concentrations will, however, increase the risk for ADRs, in particular with supratherapeutic drug concentrations.

A Review of CYP-Mediated Drug Interactions: Mechanisms and In Vitro Drug-Drug Interaction Assessment

Drug metabolism is a major determinant of drug concentrations in the body. Drug-drug interactions (DDIs) caused by the co-administration of multiple drugs can lead to alteration in the exposure of the victim drug, raising safety or effectiveness concerns. Assessment of the DDI potential starts with in vitro experiments to determine kinetic parameters and identify risks associated with the use of comedication that can inform future clinical studies. The diverse range of experimental models and techniques has significantly contributed to the examination of potential DDIs. Cytochrome P450 (CYP) enzymes are responsible for the biotransformation of many drugs on the market, making them frequently implicated in drug metabolism and DDIs. Consequently, there has been a growing focus on the assessment of DDI risk for CYPs. This review article provides mechanistic insights underlying CYP inhibition/induction and an overview of the in vitro assessment of CYP-mediated DDIs.

Pharmacogenetics in the Treatment of Huntington’s Disease: Review and Future Perspectives

Huntington’s disease (HD) is an autosomal dominant progressive brain disorder, caused by a pathological expansion of a CAG repeat that encodes the huntingtin gene. This genetic neurodegenerative rare disease is characterized by cognitive, motor, and neuropsychiatric manifestations. The aim of the treatment is symptomatic and addresses the hyperkinetic disorders (chorea, dystonia, myoclonus, tics, etc.) and the behavioural and cognitive disturbances (depression, anxiety, psychosis, etc.) associated with the disease. HD is still a complex condition in need of innovative and efficient treatment. The long-term goal of pharmacogenetic studies is to use genotype data to predict the effective treatment response to a specific drug and, in turn, prevent potential undesirable effects of its administration. Chorea, depression, and psychotic symptoms have a substantial impact on HD patients’ quality of life and could be better controlled with the help of pharmacogenetic knowledge. We aimed to carry out a review of the available publications and evidence related to the pharmacogenetics of HD, with the objective of compiling all information that may be useful in optimizing drug administration. The impact of pharmacogenetic information on the response to antidepressants and antipsychotics is well documented in psychiatric patients, but this approach has not been investigated in HD patients. Future research should address several issues to ensure that pharmacogenetic clinical use is appropriately supported, feasible, and applicable.

The pharmacogenetics of CYP2D6 and CYP2C19 in a case series of antidepressant responses

Pharmacogenetics has potential for optimizing use of psychotropics. CYP2D6 and CYP2C19 are two clinically relevant pharmacogenes in the prescribing of antidepressants. Using cases recruited from the Understanding Drug Reactions Using Genomic Sequencing (UDRUGS) study, we aimed to evaluate the clinical utility of genotyping CYP2D6 and CYP2C19 in antidepressant response. Genomic and clinical data for patients who were prescribed antidepressants for mental health disorders, and experienced adverse reactions (ADRs) or ineffectiveness, were extracted for analysis. Genotype-inferred phenotyping of CYP2D6 and CYP2C19 was carried out as per Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines. A total of 52 patients, predominantly New Zealand Europeans (85%) with a median age (range) of 36 years (15-73), were eligible for analysis. Thirty-one (60%) reported ADRs, 11 (21%) ineffectiveness, and 10 (19%) reported both. There were 19 CYP2C19 NMs, 15 IMs, 16 RMs, one PM and one UM. For CYP2D6, there were 22 NMs, 22 IMs, four PMs, three UMs, and one indeterminate. CPIC assigned a level to each gene-drug pair based on curated genotype-to-phenotype evidence. We analyzed a subgroup of 45 cases, inclusive of response type (ADRs/ineffectiveness). Seventy-nine (N = 37 for CYP2D6, N = 42 for CYP2C19) gene-drug/antidepressant-response pairs with CPIC evidence levels of A, A/B, or B were identified. Pairs were assigned as 'actionable' if the CYP phenotypes potentially contributed to the observed response. We observed actionability in 41% (15/37) of CYP2D6-antidepressant-response pairs and 36% (15/42) of CYP2C19-antidepressant-response pairs. In this cohort, CYP2D6 and CYP2C19 genotypes were actionable for a total of 38% pairs, consisting of 48% in relation to ADRs and 21% in relation to drug ineffectiveness.

Precision Medicine in Antidepressants Treatment

Precision medicine uses innovative approaches to improve disease prevention and treatment outcomes by taking into account people's genetic backgrounds, environments, and lifestyles. Treatment of depression is particularly challenging, given that 30-50% of patients do not respond adequately to antidepressants, while those who respond may experience unpleasant adverse drug reactions (ADRs) that decrease their quality of life and compliance. This chapter aims to present the available scientific data that focus on the impact of genetic variants on the efficacy and toxicity of antidepressants. We compiled data from candidate gene and genome-wide association studies that investigated associations between pharmacodynamic and pharmacokinetic genes and response to antidepressants regarding symptom improvement and ADRs. We also summarized the existing pharmacogenetic-based treatment guidelines for antidepressants, used to guide the selection of the right antidepressant and its dose based on the patient's genetic profile, aiming to achieve maximum efficacy and minimum toxicity. Finally, we reviewed the clinical implementation of pharmacogenomics studies focusing on patients on antidepressants. The available data demonstrate that precision medicine can increase the efficacy of antidepressants and reduce the occurrence of ADRs and ultimately improve patients' quality of life.

A state-of-the-art review on the nanomaterial-based sensor for detection of venlafaxine

Venlafaxine (denoted as VFX), a member of the most extensively prescribed antidepressants, is used to handle major depressive disorder, panic disorder and anxiety. This medication affects brain chemistry, which could cause an imbalance in depressed people. VFX and its metabolites, on the other hand, are pollutants in the water environment. Through movement and transformation in several procedures like adsorption, photolysis, hydrolysis and biodegradation, they have harmed living creatures, resulting in the enhancement of diverse active chemicals found in the environment. As a result, determining VFX at modest concentrations with excellent sensitivity, specificity and repeatability are critical. To quantify VFX, various analytical methodologies have been developed. Electroanalytical processes, on the other hand, have piqued interest because of their superior benefits over traditional techniques such as speed, sensitivity, directness and affordability. Subsequently, the purpose of this article is to show how to determine VFX electrochemically using a wide range of electrodes, including CPE, GCE, MCE, SPE, PGE and ISE.

Effects of Zuojin Pill (Rhizoma Coptidis and Fructus Evodiae preparation) on the pharmacokinetics and side effects of venlafaxine in humans

Venlafaxine (VEN), a first-line antidepressant, and Zuojin Pill (ZJP), a common herbal medicine consisting of Rhizoma Coptidis and Fructus Evodiae, are high likely co-administered in China. ZJP could significantly inhibit VEN pharmacokinetics in vitro and in rats through suppression of CYP2D6 activity. To date, however, no clinical study has demonstrated the clinical relevance. Here, the VEN pharmacokinetics at a single dose of VEN with or without co-administration of ZJP was compared. ZJP had a weak HDI on the pharmacokinetics of VEN. The geometric means of C_max and AUC_0-∞ of VEN increased by 36.7% and 34.6%, respectively, and the corresponding 90% CIs of geometric mean ratios (GMRs) exceed outside bioequivalent range of 0.80-1.25. However, the corresponding 90% CIs of GMRs of these parameters for ODV were within the range. Since ODV exposure (AUC), approximately 3.4-fold higher than that of VEN, hardly changed, the systemic exposure of VEN active moiety (VEN + ODV) with ZJP increased slightly (≤ 8.5%) compared with that of VEN alone. In addition, the incidence of VEN-related side effects, especially gastrointestinal relevance, were significantly reduced with ZJP. Therefore, rational concomitant use of VEN and ZJP might have low risk of HDI and be promising in clinical practice.

Pre-clinical drug-drug interactions (DDIs) of gefitinib with/without losartan and selective serotonin reuptake inhibitors (SSRIs): citalopram, fluoxetine, fluvoxamine, paroxetine, sertraline, and venlafaxine

Objective

Methods

Results

Conclusion

•

In vitro hepatocytes assays can predict relevant drug-drug interactions (DDIs).

•

Proof-of concept data testing can provide a clear insight of multidrug regimen DDIs.

•

Classifying drugs as inhibitors/inducers alone cannot successfully identify DDIs.

•

Regimens requiring three or more drugs may cause significant DDIs (p-value < 0.05).

•

SSRI metabolism by human hepatocytes can be affected by gefitinib and losartan.

Transplacental transfer of venlafaxine evaluated by ex vivo perfusion

INTRODUCTION

Depression is frequent among pregnant women and decision for treatment with antidepressants needs careful consideration of risks for the fetus. Since data regarding fetal antidepressant exposure are rare, we aimed to evaluate transplacental transfer of venlafaxine, a selective norepinephrine reuptake inhibitor.

METHODS

Ex vivo human placental perfusion experiments were conducted in double closed set-up. Venlafaxine (18.1 ± 2.1 μg/L) was offered in maternal circuit and maternal-to-fetal transfer was monitored over a period of 3h. Venlafaxin and O-desmethylvenlafaxine concentrations were determined by HPLC-MS in maternal and fetal perfusion medium.

RESULTS

We observed maternal-to-fetal transfer of venlafaxine within 5 min perfusion. The concentration equilibrium was approximated between maternal (7.5 ± 0.5 μg/L) and fetal (6.5 ± 0.6 μg/L) compartment at time point 180 min, which corresponds to a fetal-maternal (FM) ratio of 0.89.

DISCUSSION

Our results are comparable with in vivo data from an observational study which emphasizes that the ex vivo placental perfusion model is suitable for systematic evaluation of fetal antidepressant exposure.

Effects of CYP2D6 Genotypes on Venlafaxine Metabolism in Japanese Psychiatric Patients With Depression

BACKGROUND

Venlafaxine (VEN) is primarily metabolized by CYP2D6. Although several studies have reported the significant effects of CYP2D6 on VEN and O-desmethylvenlafaxine (ODV) pharmacokinetics in Whites, limited data are available regarding the effects of the Asian-specific CYP2D6 genotype on VEN metabolism. This study evaluated the effects of the CYP2D6*10 and CYP2D6*5 genotypes on the steady-state plasma concentrations of VEN and ODV in Japanese patients.

METHODS

This study included 75 Japanese patients with depression who were treated with VEN. Steady-state plasma concentrations of VEN and ODV were measured using liquid chromatography. Polymerase chain reaction was used to determine CYP2D6 genotypes. A stepwise multiple regression analysis was performed to analyze the relationship between independent variables (sex, age, smoking habit, and number of mutated alleles, CYP2D6*10 and CYP2D6*5), subject-dependent variables (plasma concentrations of VEN and ODV [all corrected for dose and body weight]), and the ODV/VEN ratio.

RESULTS

Significant correlations were observed between the daily dose of VEN (corrected for body weight) and plasma concentrations of VEN (r = 0.498, P < 0.001) and ODV (r = 0.380, P = 0.001); ODV plasma concentrations were approximately 3.2 times higher than VEN plasma concentrations (VEN versus ODV = 18.60 ng/mL versus 59.10 ng/mL). VEN plasma concentrations (corrected for dose and body weight) did not differ with differing numbers of CYP2D6-mutated alleles. However, the ODV/VEN ratio decreased as the number of mutated CYP2D6 alleles increased (P = 0.001).

CONCLUSIONS

This is the first study to examine the effects of CYP2D6*10 in a clinical setting. Although no effects on the plasma concentrations of VEN or ODV were observed, CYP2D6 polymorphism affects the ODV/VEN ratio. Further studies are needed to confirm the clinical relevance of these findings.

Endogenous and iatrogenic sources of variability in response to opioid therapy in Post-Surgical and injured orthopedic patients

BACKGROUND

Hydrocodone is the most prescribed opioid in the US. The objective was to evaluate associations between genetic, intrinsic, and extrinsic patient factors, plasma hydrocodone and metabolites, common side effects, and pain scores in a cohort of orthopedic surgery patients.

METHODS

Data for each patient was collected by review of the electronic hospital record (EHR), and patient interview. Patients were recruited from those with trauma or undergoing scheduled elective surgery for total knee replacement or total hip at the University of Louisville Hospital, Baptist East Hospital, and Jewish Hospital, Louisville, KY. Plasma opiate concentrations and a targeted genotyping panel was performed.

RESULTS

There were statistically significant correlations with daily (p < 0.001) and total dose (p = 0.002) of hydrocodone in hospital and duration of opioid therapy. The length of opioid administration was significantly shorter in CYP2D6 EM/UM versus CYP2D6 PM/IM patients (p = 0.018). Subjects with the OPRM1 c.118G variant were also on opioids longer (p = 0.022). The effect of co-administration of a CYP2D6 inhibitor had a significant effect on the length of opioid therapy (P < 0.001). And not surprisingly the effect of the inhibitor adjusted CYP2D6 phenotype was greater in both the hospital stay period and days of opioid use post hospital discharge (p < 0.001).

CONCLUSIONS

Based on this study, patients should be evaluated for the use of inhibitors of CYP2D6, during hydrocodone therapy can alter the phenotype of the patient (phenocopy) and increase the probability that the patient will be on opioids for longer periods of time.

Pharmacogenetic-Guided Antidepressant Selection as an Opportunity for Interprofessional Collaboration: A Case Report

In the herein reported case of a 42-year-old woman diagnosed with anxiety and depression, a long history of antidepressant ineffectiveness and adverse drug reactions was decisive for an in-depth medication review including pharmacogenetic panel testing. In detail, treatment attempts with paroxetine and escitalopram were ineffective and discontinued due to subjective gastrointestinal intolerance. Due to the worsening of the depression after the failed treatment attempts, admission to our clinic became necessary. Herein, owing to the collaboration of psychiatrists with clinical pharmacists, individualized incorporation of pharmacogenetic data into the process of antidepressant selection was enabled. We identified vortioxetine as a suitable therapeutic, namely for being most likely pharmacokinetically unaffected as predicted by pharmacogenetic panel testing and taking into account the current comedication, as well as for its favorable action profile. Herein, our collaborative effort proved to be successful and resulted in the patient's depression remission and clinic discharge with the interprofessionally selected pharmacotherapy. This exemplary case not only highlights the potential benefits and challenges of pre-emptive pharmacogenetic testing in antidepressant prescription, but also proposes an approach on how to put pharmacogenetics into practice.

CYP2D6*10 polymorphism and the enantioselective O-desmethylation of S-(+)- and R-(-)-venlafaxine in Japanese psychiatric patients

According to previous studies, R-(-)-venlafaxine (VEN) has higher enantioselectivity than S-(+)-VEN, and the plasma concentration of R-(-)-VEN varies depending on CYP2D6 activity. Therefore, we examined the pharmacokinetic effects of CYP2D6*10 genotypes on the steady-state concentrations of the enantiomers of VEN. The individuals were 71 Japanese depressed patients treated with racemic VEN. The concentrations of the enantiomers of VEN and O-desmethylvenlafaxine (ODV) were measured. Polymerase chain reaction (PCR) was used to determine the CYP2D6*10 genotypes. The plasma concentrations of S-(+)-VEN were approximately 1.9-fold higher than those of R-(-)-VEN. The plasma concentrations of S-(+)-VEN and R-(-)-VEN seemed to be higher in individuals with two mutant alleles of CYP2D6*10, although no significant differences were found in the plasma levels of S-(+)-VEN and R-(-)-VEN between CYP2D6*10 genotypes. The number of mutant alleles of CYP2D6*10 was a significant factor associated with the R-(-)-ODV/R-(-)-VEN ratio (P = .004) in multiple regression analysis. This suggests that CYP2D6*10 mutations affect the metabolism of R-(-)-VEN and S-(+)-VEN. Further studies are needed to examine how these findings affect clinical practice.

Reversible Mechanisms of Enzyme Inhibition and Resulting Clinical Significance

Inhibition of a drug-metabolizing enzyme by the reversible interaction of a drug with the enzyme, thus decreasing the metabolism of another drug, is a major cause of clinically significant drug-drug interactions. This chapter defines the four reversible mechanisms of inhibition exhibited by drugs: competitive, noncompetitive, uncompetitive, and mixed competitive/noncompetitive. An in vitro procedure to determine the potential of a drug to be a reversible inhibitor is also provided. Finally, a number of examples of clinically significant drug-drug interactions resulting from reversible inhibition are described.

How Can Drug Metabolism and Transporter Genetics Inform Psychotropic Prescribing?

Many genetic variants in drug metabolizing enzymes and transporters have been shown to be relevant for treating psychiatric disorders. Associations are strong enough to feature on drug labels and for prescribing guidelines based on such data. A range of commercial tests are available; however, there is variability in included genetic variants, methodology, and interpretation. We herein provide relevant background for understanding clinical associations with specific variants, other factors that are relevant to consider when interpreting such data (such as age, gender, drug-drug interactions), and summarize the data relevant to clinical utility of pharmacogenetic testing in psychiatry and the available prescribing guidelines. We also highlight areas for future research focus in this field.

Therapeutic Drug Monitoring of Venlafaxine and Impact of Age, Gender, BMI, and Diagnosis

Depression is a common mental disorder affecting more than 264 million people in the world and 5.1% of the Slovak population. Although various antidepressant approaches have been used; still, about 40% of patients do not respond to a first-choice drug administration and one third of patients do not achieve total remission. Therapeutic drug monitoring (TDM) is a method used for quantification and interpreting the drug concentrations in plasma in order to optimize the pharmacotherapy. The aim of this study was to measure the plasma concentrations of venlafaxine, the fourth most prescribed antidepressant in Slovakia, as well as its active metabolite and interpret them with the relevant patients’ characteristics.

The study was of retrospective nature and 28 adult patients in total were included. The concentrations of venlafaxine and its active metabolite O-desmethylvenlafaxine (ODV) in plasma were quantified using the validated UHPLC-MS/MS method. The effects of potential influencing factors were evaluated by a multivariate linear regression model.

Only 39% of patients reached the venlafaxine active moiety concentrations within the recommended therapeutic range. Plasma concentrations were dependent on age, gender, and duration of the therapy. Venlafaxine metabolism expressed as a metabolite-to-parent concentrations ratio was influenced by a combination of age, gender, and body mass index (BMI). We did not observe any significant difference in plasma concentrations between the patients with a single and recurrent diagnosis of depression. Combining variables made an additive effect on plasma concentrations, for example, active moiety plasma concentrations were higher in older women. In contrast, drug metabolism was higher in older men and men with lower BMI. TDM of venlafaxine is recommended in clinical practice, especially in the elderly when beginning the pharmacotherapy.

Nifedipine Does Not Alter the Pharmacokinetics of Venlafaxine Enantiomers in Healthy Subjects Phenotyped for CYP2D6, CYP2C19, and CYP3A

Venlafaxine (VEN) is a P-glycoprotein (P-gp) substrate, and nifedipine has been described by in vitro and experimental studies as a P-gp inhibitor. The present study aimed to investigate whether nifedipine alters the kinetic disposition of VEN enantiomers and their metabolites in healthy subjects. A crossover study was conducted in 10 healthy subjects phenotyped as extensive metabolizers for cytochrome P450 (CYP) 2D6, CYP2C19, and CYP3A. In phase 1, the subjects received a single oral dose of 150 mg racemic VEN, and in phase 2, a single oral dose of 40 mg nifedipine was administered with the VEN treatment. Plasma concentrations of VEN enantiomers and their metabolites O-desmethylvenlafaxine and N, O- didesmethylvenlafaxine (ODV and DDV, respectively) were evaluated by liquid chromatography with tandem mass spectrometry up to 72 hours after drug administration. Phase 2 was compared with phase 1 using the 90% confidence interval (CI) of the ratio of geometric means for C_max and area under the curve (AUC). AUC enantiomeric ratios S-(+)/R-(-) were evaluated within each and between phases using the Wilcoxon test (P ≤ .05). The kinetic disposition of VEN was enantioselective (phase 1) with VEN S-(+)/R-(-) AUC ratio median of 2.83 (AUC_0-∞ , 526 vs 195 ng·h/mL). However, AUC median did not differ between enantiomers for the metabolites ODV (1971 vs 2226 ng·h/mL) and DDV (199 vs 151 ng·h/mL). The 90%CI of the ratio of geometric means showed that the phases are bioequivalent. A single oral dose of 40 mg nifedipine did not alter VEN enantiomer pharmacokinetics in healthy subjects.

Recent Advances in the Electrochemical Sensing of Venlafaxine: An Antidepressant Drug and Environmental Contaminant

Venlafaxine (VEN), as one of the popular anti-depressants, is widely utilized for the treatment of major depressive disorder, panic disorder, as well as anxiety. This drug influences the chemicals in the brain, which may result in imbalance in depressed individuals. However, venlafaxine and its metabolites are contaminants in water. They have exerted an adverse influence on living organisms through their migration and transformation in various forms of adsorption, photolysis, hydrolysis, and biodegradation followed by the formation of various active compounds in the environment. Hence, it is crucial to determine VEN with low concentrations in high sensitivity, specificity, and reproducibility. Some analytical techniques have been practically designed to quantify VEN. However, electroanalytical procedures have been of interest due to the superior advantages in comparison to conventional techniques, because such methods feature rapidity, simplicity, sensitivity, and affordability. Therefore, this mini-review aims to present the electrochemical determination of VEN with diverse electrodes, such as carbon paste electrodes, glassy carbon electrodes, mercury-based electrodes, screen-printed electrodes, pencil graphite electrodes, and ion-selective electrodes.

Influence of Zuojin Pill on the Metabolism of Venlafaxine in Vitro and in Rats and Associated Herb-Drug Interaction

Venlafaxine (VEN), a first-line antidepressant, and Zuojin Pill (ZJP), a common Chinese herbal medicine consisting of Rhizoma Coptidis and Fructus Evodiae, have a high likelihood of combination usage in patients with depression with gastrointestinal complications. ZJP exhibits inhibitory effects on recombinant human cytochrome P450 isoenzymes (rhP450s), especially on CYP2D6, whereas VEN undergoes extensive metabolism by CYP2D6. From this perspective, we investigated the influence of ZJP on the metabolism of VEN in vitro and in rats for the first time. In this study, ZJP significantly inhibited the metabolism of VEN in both rat liver microsomes (RLM) and human liver microsomes (HLM); meanwhile, it inhibited the O-demethylation catalytic activity of RLM, HLM, rhCYP2D6*1/*1, and rhCYP2D6*10/*10, primarily through CYP2D6, with IC₅₀ values of 129.9, 30.5, 15.4, and 2.3 μg/ml, respectively. Furthermore, the inhibitory effects of ZJP on hepatic metabolism and pharmacokinetics of VEN could also be observed in the pharmacokinetic study of rats. The area under drug concentration-time curve₀-_{24 hour} of VEN and its major metabolite O-desmethylvenlafaxine (ODV) increased by 39.6% and 22.8%, respectively. The hepatic exposure of ODV decreased by 57.2% 2 hours after administration (P = 0.014). In conclusion, ZJP displayed inhibitory effects on hepatic metabolism and pharmacokinetics of VEN in vitro and in rats mainly through inhibition of CYP2D6 activity. The human pharmacokinetic interaction between ZJP and VEN and its associated clinical significance needed to be seriously considered. SIGNIFICANCE STATEMENT: Zuojin Pill, a commonly used Chinese herbal medicine, demonstrates significant inhibitory effects on hepatic metabolism and pharmacokinetics of venlafaxine in vitro and in rats mainly through suppression of CYP2D6 activity. The human pharmacokinetic interaction between Zuojin Pill and venlafaxine and its associated clinical significance needs to be seriously considered.

Pharmacotherapeutic profile of venlafaxine

When selecting an antidepressant, a number of factors must be considered. These considerations are summarized under the mnemonic STEPS: Safety, Tolerability, Efficacy, Payment (eg, cost-effectiveness), and Simplicity of use. Venlafaxine is the first of a new class of antidepressants that selectively blocks the serotonin and noradrenaline uptake pumps without blocking muscarinic, histaminergic and adrenergic receptors or inhibiting sodium fast channels. Because venlafaxine avoids these mechanisms of action, it has a wide therapeutic index, an improved tolerability profile and a reduced risk of causing pharmacodynamically mediated drug-drug interactions when compared to tricyclic antidepressants (TCAs). In contrast to some other new antidepressants, venlafaxine also avoids effects on cytochrome P450 which are likely to cause clinically meaningful, pharmacokinetically mediated drug-drug interactions. The effects on the uptake pumps of both serotonin and noradrenaline appear to be responsible for some of venlafaxine's unique features in terms of antidepressant efficacy, including its ascending antidepressant dose-response curve and its apparent rapid onset of antidepressant action at the upper end of its clinically relevant dosing range. Venlafaxine is effective in a broad spectrum of patients, including outpatients and inpatients, those with and without melancholia, patients with symptoms of anxiety or agitation or retardation and patients with first time or recurrent episodes of major depression. An important factor when selecting an antidepressant is the simplicity of the dosing regimen and the ability to rapidly and confidently achieve the optimal dose for the patient. In this regard, venlafaxine can be initiated at a clinically effective dose from the beginning. If the patient fails to respond to this dose, there is evidence that increased antidepressant efficacy can be achieved by increasing the dose rather than having to resort to an augmentation strategy or switch to another class of antidepressants. In the immediate release form, venlafaxine has proven antidepressant efficacy when using a twice-or three-times-a-day schedule. A sustained release formulation is expected to be marketed soon and will permit once-a-day-dosing.

A review of the efficacy and tolerability of venlafaxine

Venlafaxine is a selective serotonin norepinephrine reuptake inhibitor with no activity at muscarinic, histaminergic or adrenergic receptors. The antidepressant activity of venlafaxine has been demonstrated in placebo-controlled and active comparator-controlled clinical trials. Venlafaxine was effective in outpatients and hospitalized patients with major depression and in those with melancholia, agitated or retarded symptoms, and refractory or treatment-resistant depression. Venlafaxine was at least as effective as comparative antidepressants and was more effective than fluoxetine or imipramine in some trials. A positive dose-response relationship has been shown with venlafaxine. When doses of venlafaxine are titrated rapidly upward, an onset of antidepressant action has been detected within one week in some studies. Venlafaxine is well tolerated during short- and long-term treatment. The most common adverse effects are nausea, somnolence and dry mouth. The overall tolerability of venlafaxine appears to exceed that of tricyclic antidepressants and compares favorably with that of selective serotonin reuptake inhibitors. Venlafaxine is a novel antidepressant that is appropriate for first-line therapy in patients with major depression.

The influence of bariatric surgery on oral drug bioavailability in patients with obesity: A systematic review

Anatomical changes in the gastrointestinal tract and subsequent weight loss may influence drug disposition and thus drug dosing following bariatric surgery. This review systematically examines the effects of bariatric surgery on drug pharmacokinetics, focusing especially on the mechanisms involved in restricting oral bioavailability. Studies with a longitudinal before-after design investigating the pharmacokinetics of at least one drug were reviewed. The need for dose adjustment following bariatric surgery was examined, as well as the potential for extrapolation to other drugs subjected to coinciding pharmacokinetic mechanisms. A total of 22 original articles and 32 different drugs were assessed. The majority of available data is based on Roux-en-Y gastric bypass (RYGBP) (18 of 22 studies), and hence, the overall interpretation is more or less limited to RYGBP. In the case of the majority of studied drugs, an increased absorption rate was observed early after RYGBP. The effect on systemic exposure allows for a low degree of extrapolation, including between drugs subjected to the same major metabolic and transporter pathways. On the basis of current understanding, predicting the pharmacokinetic change for a specific drug following RYGBP is challenging. Close monitoring of each individual drug is therefore recommended in the early postsurgical phase. Future studies should focus on the long-term effects of bariatric surgery on drug disposition, and they should also aim to disentangle the effects of the surgery itself and the subsequent weight loss.

Significantly lower CYP2D6 metabolism measured as the O/N-desmethylvenlafaxine metabolic ratio in carriers of CYP2D6*41 versus CYP2D6*9 or CYP2D6*10: a study on therapeutic drug monitoring data from 1003 genotyped Scandinavian patients

AIMS

CYP2D6*9, CYP2D6*10 and CYP2D6*41 are the most frequent reduced-function CYP2D6 alleles in Caucasians. Despite lacking in vivo evidence, they are collectively classified with an enzyme activity score of 0.5. Thus, the aim of this study was to compare the functional impact of CYP2D6*9, CYP2D6*10 and CYP2D6*41 on CYP2D6 metabolism in a large patient population.

METHODS

A total of 1003 patients (mainly Caucasians) with data on CYP2D6 genotype and serum concentrations of venlafaxine and metabolites were included from a therapeutic drug monitoring service in Oslo, Norway. The O-desmethyl-to-N-desmethyl-venlafaxine metabolic ratio (MR) was applied as CYP2D6 biomarker and compared (Mann-Whitney) between carriers of CYP2D6*9-10 (merged) and CYP2D6*41, either combined with CYP2D6*1 or non-coding (null) alleles. MR subgroup estimates were obtained by multiple linear regression for calculations of CYP2D6*9-10 and CYP2D6*41 activity scores.

RESULTS

MR was significantly lower in carriers of CYP2D6*41 than CYP2D6*9-10 (P < 0.002). The majority of CYP2D6*41/null carriers (86.7%) had MR in the observed range of CYP2D6null/null carriers compared with the minority of CYP2D6*9-10/null carriers (17.4%). CYP2D6 genotype explained 60.7% of MR variability in the multivariate analysis providing subgroup estimates of 9.54 (95% CI; 7.45-12.20), 3.55 (2.06-6.10), 1.33 (0.87-2.05) and 0.47 (0.35-0.61) in carriers of CYP2D6*1/null (n = 269), CYP2D6*9-10/null (n = 17), CYP2D6*41/null (n = 30) and CYP2D6null/null (n = 95), respectively. Based on these estimates, the calculated activity score of CYP2D6*41 was 0.095 compared to 0.34 for CYP2D6*9-10.

CONCLUSIONS

CYP2D6 metabolism measured as the O/N-desmethylvenlafaxine ratio is significantly lower in Scandinavian carriers of CYP2D6*41 vs. CYP2D6*9-10. Thus, these alleles should be differentiated when classifying CYP2D6 phenotype from genotype.

Assessment of CYP2D6 re-activation after inhibitory effect of MDMA using tramadol as a probe

Background

In recent years, the use of tramadol as a probe drug for human cytochrome p450 2D6 (CYP2D6) has been investigated. The objective of this study was to assess the recovery of rat CYP2D1 enzymatic activity after mechanism-based inhibition induced by a single dose of ecstasy (MDMA, 3,4-methylenedioxymethamphetamine) and evaluation of the tramadol ability as a probe drug. CYP2D1 is orthologous in rats to human CYP2D6 and was employed in the current study.

Methods

A total of 16 male rats were selected and divided into control and treatment groups. The control group did not receive MDMA, while rats in the treatment group received a single dose of MDMA (1 mg/kg) and were subsequently divided into groups that were tested at 1 h, 10 days or 30 days post-administration. The rats were subjected to liver perfusion with Krebs-Heinslet buffer containing tramadol for 60 min and the tramadol and M1 levels were determined by HPLC-fluorescence.

Results

The enzymatic activity of CYP2D1 for the 1-h group decreased significantly when compared with the control group (p<0.05). Moreover, enzymatic activity increased non-significantly in the 10- and 30-day groups in comparison with the control group. The concentration and AUC0−60 of tramadol increased in the 1-h and 10-day groups when compared with the control group but decreased in the 30-day group; however, none of these changes was statistically significant (p>0.05). The M1 metabolic ratio in the 1-h group decreased significantly when compared with the control group (p<0.05). The M1 metabolic ratio of the 10-day group increased and of the 30-day group decreased, but neither of these changes were significant.

Conclusions

Regardless of the genotype, the enzymatic activity of rat CYP2D1 recovered by 10 days post-administration of MDMA. It appears that tramadol, irrespective of its stereoselectivity, is not able to appraise rat hepatic CYP2D1 activity. It can be extrapolated that tramadol is a not suitable probe drug for human hepatic CYP2D1 because CYP2D1 in rats is orthologous to human CYP2D6. Further animal and human studies are required to confirm this hypothesis.

The activity of brain and liver cytochrome P450 2D (CYP2D) is differently affected by antidepressants in the chronic mild stress (CMS) model of depression in the rat

The effect of two second-generation antidepressants escitalopram and venlafaxine on the activity of brain and liver cytochrome P450 2D (CYP2D) involved in the metabolism of psychotropics and neurotransmitters was determined in the chronic mild stress (CMS) model of depression. Escitalopram or venlafaxine (10 mg/kg ip/day each) were administered to control and CMS rats for 5 weeks. The activity of CYP2D was studied by measurement of the rate of bufuralol 1'-hydroxylation in microsomes derived from the liver or different brain structures. The obtained results indicate that CMS and the studied antidepressants had different effects on the CYP2D activity depending on the location of the enzyme. In the brain, CMS produced an increase in the CYP2D activity in the hippocampus. Chronic escitalopram or venlafaxine had no effect on the CYP2D activity in the brain of nonstressed rats, however, the antidepressants increased the enzyme activity in the frontal cortex, hypothalamus and cerebellum of stressed animals. In the liver, CMS did not affect the CYP2D activity, while chronic escitalopram or venlafaxine significantly decreased the CYP2D activity and protein level in nonstressed and stressed rats. We conclude that: 1) CMS stimulates the CYP2D activity in the hippocampus and triggers the stimulatory effect of antidepressants on CYP2D in other brain structures; 2) the local brain metabolism of CYP2D substrates (neurosteroids, neurotransmitters, psychotropics) may be enhanced by CMS and/or antidepressants; 3) in contrast to the brain, the liver metabolism of CYP2D substrates may be slower during long-term treatment with escitalopram or venlafaxine.

Rapid solid-phase extraction coupled with GC-MS method for the determination of venlafaxine in rat plasma: Application to the drug-drug pharmacokinetic interaction study of venlafaxine combined with fluoxetine

A rapid and sensitive gas chromatography with mass spectrometry method for the determination of venlafaxine in rat plasma has been developed and applied to a drug-drug interaction study of fluoxetine on pharmacokinetics of venlafaxine in rats. Rat plasma was spiked with 2% aqueous ammonia before subjected to preactivated C₁₈ solid-phase extraction columns and eluted with methanol. No endogenous interferences were observed under optimal condition. The calibration curve was linear (R²  = 0.9994) in the range of 10-1000 ng/mL. The quantification limit of venlafaxine in rat plasma was 10 ng/mL. The accuracy was in the range of 85-110%, and the extraction recovery was no less than 50%. Both the intra- and interday precision were 5.0-10.7%. The concentration-time curve showed that plasma concentrations of the coadministration group (group B) were higher than that of single dose group (group A). Both values of C_max (0.069 mg/L) and AUC_0→∞ (0.291 mg h/L) in group B were statistically greater than that of C_max (0.046 mg/L) and AUC_0→∞ (0.181 mg·h/L) in group A (P < 0.05). The results indicated that a significant effect of fluoxetine was shown on the pharmacokinetics of venlafaxine, suggesting that drug-drug interactions are of concern for the treatment of depression with the combined use of venlafaxine and fluoxetine.

Should a routine genotyping of CYP2D6 and CYP2C19 genetic polymorphisms be recommended to predict venlafaxine efficacy in depressed patients treated in psychiatric settings?

AIM

The antidepressant venlafaxine (VEN) is metabolized by CYP2D6 and CYP2C19. The aim of this study was to assess the relevance of generalizing to daily practice the genotyping of CYP2D6 and CYP2C19 to predict VEN efficacy in depressed patients treated in psychiatric settings.

PATIENTS & METHODS

This study was nested in a naturalistic cohort, with 206 patients requiring a new antidepressant treatment and genotyped for CYP2D6 *3, *4, *5 del, *6, *2xN, *10, *41 and CYP2C19 *2, *3, *4, *5, *17 alleles.

RESULTS

CYP2D6 and CYP2C19 phenotypes were associated neither with the Hamilton depression rating scale score improvement, nor with response and remission.

CONCLUSION

Routine CYP2D6 and CYP2C19 genotyping cannot be recommended to predict VEN efficacy in depressed patients treated in psychiatry settings.

Palpitations and Asthenia Associated with Venlafaxine in a CYP2D6 Poor Metabolizer and CYP2C19 Intermediate Metabolizer

Cardiotoxicity has been extensively reported in venlafaxine (VEN) overdoses. Asthenia is also among the common side effects described for this antidepressant. VEN is metabolized mainly by CYP2D6 and to a minor extent by CYP2C19 to the major active metabolite O-desmethylvenlafaxine (ODV). Altered pharmacokinetic parameters in patients with polymorphisms in the CYP2D6 and CYP2C19 genes that result in decreased enzymatic activity have been documented. Here we describe a patient case of VEN associated palpitations and asthenia. The patient takes VEN extended release 150 mg twice daily. Genotyping confirmed the patient is a poor metabolizer for CYP2D6 and an intermediate metabolizer for CYP2C19. We propose that the palpitations and asthenia are related to sustained VEN exposure due to reduced metabolism.

A novel prodrug strategy to improve the oral absorption of O-desmethylvenlafaxine

O-Desmethylvenlafaxine (desvenlafaxine, ODV) is the active metabolite of venlafaxine, with similar activity and less risk for pharmacokinetic drug interactions compared to its parent compound venlafaxine. The purpose of this study was to design a series of esters of ODV and assess their potential as ODV prodrugs with improved bioavailability and brain uptake. Seven esters were synthesized and pharmacokinetic screening was performed in rats. The monoester formed on the phenolic hydroxyl of ODV (ODVP-1, ODVP-2, ODVP-3 and ODVP-5) could be degraded to ODV in rat plasma. These four compounds confirmed as possible prodrugs were then studied to evaluated the relative bioavailability of ODV they produced in beagle dogs. ODVP-1, ODVP-2 and ODVP-3 demonstrated higher relative bioavailability of ODV. Finally, ODVP-1, ODVP-2 and ODVP-3 were studied to evaluate their brain uptake in rats. The concentration of ODV in the rat plasma, brain and hypothalamus after administration of ODVP-1, ODVP-2 or ODVP-3 was higher compared with that of ODV. The higher bioavailability, improved pharmacokineics properties and more rapid penetration and translation of ODV suggest that ODVP-1, ODVP-2 or ODVP-3 may warrant further development and application as ODV prodrugs.

Pharmacogenetics of CYP2D6 and tamoxifen therapy: Light at the end of the tunnel?

The clinical usefulness of assessing the enzymatic activity of CYPD6 in patients taking tamoxifen had been longly debated. In favour of preemptive evaluation of phenotypic profile of patients is the strong pharmacologic rationale, being that the formation of endoxifen, the major and clinically most important metabolite of tamoxifen, is largely dependent on the activity of CYP2D6. This enzyme is highly polymorphic for which the activity is largely depending on genetics, but that can also be inhibited by a number of drugs, i.e. antidepressants, which are frequently used in patients with cancer. Unfortunately, the clinical trials that have been published in the last years are contradicting each other on the association between CYP2D6 and significant clinical endpoints, and for this reason CYP2D6 genotyping is at present not generally recommended. Despite this, the CYP2D6 genotyping test for tamoxifen is available in many laboratories and it may still be an appropriate test to use it in specific cases.

Applicability of the Rayleigh equation for enantioselective metabolism of chiral xenobiotics by microsomes, hepatocytes and in-vivo retention in rabbit tissues

In this study we propose a new approach for analyzing the enantioselective biodegradation of some antidepressant drugs mediated by human and rat liver microsomes by using the Rayleigh equation to describe the enantiomeric enrichment−conversion dependencies. Analysis of reported degradation data of additional six pesticides, an alpha blocker and a flame retardant by microsomes or hepatocytes in vitro reaffirmed the universality of the approach. In all the in vitro studied cases that involved enantioselective degradation, a Rayleigh dependence of the enantiomeric enrichment was observed. Published data regarding in vivo retention of myclobutanil in liver, kidney, muscle and brain tissues of rabbits following injection of the racemate were remodeled showing prevalence of the Rayleigh law for the chiral enrichment of the fungicide in the various tissues. This approach will revolutionize data organization in metabolic pathway research of target xenobiotics by either liver microsomes, hepatocytes or their organ-specific in vivo retention. The fact that the enantiomeric enrichment as a function of the conversion can be described by a single quantifier, will pave the road for the use of structure activity predictors of the enantiomeric enrichment and for mechanistic discrimination based on parametric dependence of the quantifier.

Where Failure Is Not an Option -Personalized Medicine in Astronauts

Drug safety and efficacy are highly variable among patients. Most patients will experience the desired drug effect, but some may suffer from adverse drug reactions or gain no benefit. Pharmacogenetic testing serves as a pre-treatment diagnostic option in situations where failure or adverse events should be avoided at all costs. One such situation is human space flight. On the international space station (ISS), a list of drugs is available to cover typical emergency settings, as well as the long-term treatment of common conditions for the use in self-medicating common ailments developing over a definite period. Here, we scrutinized the list of the 78 drugs permanently available at the ISS (year 2014) to determine the extent to which their metabolism may be affected by genetic polymorphisms, potentially requiring genotype-specific dosing or choice of an alternative drug. The purpose of this analysis was to estimate the potential benefit of pharmacogenetic diagnostics in astronauts to prevent therapy failure or side effects.

Pharmacokinetic and pharmacodynamic drug interactions with ethanol (alcohol)

Ethanol (alcohol) is one of the most widely used legal drugs in the world. Ethanol is metabolized by alcohol dehydrogenase (ADH) and the cytochrome P450 (CYP) 2E1 drug-metabolizing enzyme that is also responsible for the biotransformation of xenobiotics and fatty acids. Drugs that inhibit ADH or CYP2E1 are the most likely theoretical compounds that would lead to a clinically significant pharmacokinetic interaction with ethanol, which include only a limited number of drugs. Acute ethanol primarily alters the pharmacokinetics of other drugs by changing the rate and extent of absorption, with more limited effects on clearance. Both acute and chronic ethanol use can cause transient changes to many physiologic responses in different organ systems such as hypotension and impairment of motor and cognitive functions, resulting in both pharmacokinetic and pharmacodynamic interactions. Evaluating drug interactions with long-term use of ethanol is uniquely challenging. Specifically, it is difficult to distinguish between the effects of long-term ethanol use on liver pathology and chronic malnutrition. Ethanol-induced liver disease results in decreased activity of hepatic metabolic enzymes and changes in protein binding. Clinical studies that include patients with chronic alcohol use may be evaluating the effects of mild cirrhosis on liver metabolism, and not just ethanol itself. The definition of chronic alcohol use is very inconsistent, which greatly affects the quality of the data and clinical application of the results. Our study of the literature has shown that a significantly higher volume of clinical studies have focused on the pharmacokinetic interactions of ethanol and other drugs. The data on pharmacodynamic interactions are more limited and future research addressing pharmacodynamic interactions with ethanol, especially regarding the non-central nervous system effects, is much needed.

Is complementary and alternative therapy effective for women in the climacteric period?

Vasomotor symptoms start about 2 years prior to menopause in women who are approaching menopause, and early menopause symptoms appear including emotional disturbance and anxiety, followed by physical changes such as vaginal dryness, urinary incontinence and skin wrinkles. As time progresses, osteoporosis, cardiovascular diseases, and dementia occur consecutively. Hormone therapy is primarily considered for the relief of menopause symptoms in postmenopausal women. However, as hormone replacement has emerged as a therapy that increases the potential risk of thrombosis, cerebral infarction and breast cancer, complementary and alternative medicine has drawn much attention. This study aimed to examine the types and effects of evidence-based complementary and alternative therapies that are currently used.

Influence of the CYP2D6 isoenzyme in patients treated with venlafaxine for major depressive disorder: clinical and economic consequences

Background

Antidepressant drugs are the mainstay of drug therapy for sustained remission of symptoms. However, the clinical results are not encouraging. This lack of response could be due, among other causes, to factors that alter the metabolism of the antidepressant drug. Objective: to evaluate the impact of concomitant administration of CYP2D6 inhibitors or substrates on the efficacy, tolerability and costs of patients treated with venlafaxine for major depressive disorder in clinical practice.

Methods

We designed an observational study using the medical records of outpatients. Subjects aged ≥18 years who started taking venlafaxine during 2008–2010 were included. Three study groups were considered: no combinations (reference), venlafaxine-substrate, and venlafaxine-inhibitor. The follow-up period was 12 months. The main variables were: demographic data, comorbidity, remission (Hamilton <7), response to treatment, adverse events and costs. The statistical analysis included logistic regression models and ANCOVA, with p values <0.05 considered significant.

Results

A total of 1,115 subjects were recruited. The mean age was 61.7 years and 75.1% were female. Approximately 33.3% (95% CI: 30.5 to 36.1) were receiving some kind of drug combination (venlafaxine-substrate: 23.0%, and venlafaxine-inhibitor: 10.3%). Compared with the venlafaxine-substrate and venlafaxine-inhibitor groups, patients not taking concomitant drugs had a better response to therapy (49.1% vs. 39.9% and 34.3%, p<0.01), greater remission of symptoms (59.9% vs. 50.2% and 43.8%, p<0.001), fewer adverse events (1.9% vs. 7.0% and 6.1%, p<0.05) and a lower mean adjusted cost (€2,881.7 vs. €4,963.3 and €7,389.1, p<0.001), respectively. All cost components showed these differences.

Conclusions

The patients treated with venlafaxine alone showed a better response to anti-depressant treatment, greater remission of symptoms, a lower incidence of adverse events and lower healthcare costs.