Cytochrome P450-mediated inhibition of venlafaxine metabolism by trimipramine

Multiplexed quantification of venlafaxine and metabolites in human plasma by liquid chromatography-tandem mass spectrometry

BACKGROUND

Venlafaxine (VEN) and its O-demethylated metabolite, O-desmethylvenlafaxine (ODV), are commonly prescribed serotonin-norepinephrine reuptake inhibitors, approved for the treatment of depression and anxiety. Both are metabolized to inactive metabolites via cytochrome P450 enzymes. While previous studies have focused on quantifying VEN and ODV, bioanalytical methods for the simultaneous measurement of all metabolites are needed to fully characterize the pharmacology of VEN and ODV.

METHODS

K2EDTA plasma was spiked with VEN, ODV, N-desmethylvenlafaxine (NDV), N,O-didesmethylvenlafaxine (NODDV), and N,N-didesmethylvenlafaxine (NNDDV). Drugs and metabolites were extracted via protein precipitation and quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The multiplexed assay was validated in accordance with regulatory recommendations, and evaluated in remnant plasma samples from persons prescribed venlafaxine.

RESULTS

The analytical measuring range for venlafaxine and all four metabolites was 5-800 ng/mL. Standard curves were generated via weighted quadratic (NNDDV) or linear (VEN, ODV, NDV, NODDV) regression of calibrators. Inter-assay imprecision was between 1.9-9.3% for all levels of all analytes. Minor matrix effects were observed, and both recovery efficiency and process efficiency were >96% for all analytes. All other assay validation assessments met acceptance criteria. Drug concentrations measured from remnant plasma specimens obtained from patients with current venlafaxine prescriptions (37.5-450 mg/day) yielded NDDV, NDV, and NODDV metabolite concentrations in 6/21, 14/21, and 20/21 samples, respectively. The ratio of active to inactive analytes ranged from 0.74 to 14.5, with a median of 6.39.

CONCLUSIONS

An efficient and accurate LC-MS/MS method was developed and validated for the quantification of VEN, ODV, and all three inactive metabolites in plasma. The assay met all acceptance criteria, and may be used in future studies of the pharmacokinetics of these drugs.

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.

[Therapy of mental disorders in patients with hematological malignancies]

OBJECTIVE

To assess the possibilities of therapy with minimal effective doses (MED) of psychotropic drugs for mental disorders (MD) that manifest during the treatment of hematological malignancies (HM).

MATERIAL AND METHODS

A prospective study was conducted at the National Medical Research Center for Hematology of the Russian Ministry of Health (Moscow), which included 204 (39.4%) men and 314 (60.6%) women (518 patients in total), aged 17 to 83 years (median 45 years), with various HM, in which the manifestation of MD occurred during the treatment of the underlying disease. To minimize the side-effects of psychotropic drugs and given the relatively mild level of MD, psychopharmacotherapy of patients was carried out mainly at MED. The severity of MD, manifested in patients, was assessed by the illness severity scale of the Clinical Global Impression (CGI) scale, and the effectiveness of the treatment was assessed by the improvement scale (CGI-I).

RESULTS

Mainly mild (188, 36%) and moderately pronounced (270, 52%) MD were noted in patients with HM during the treatment of the underlying disease. Severe psychopathological disorders (60, 12%) were observed much less often. Because of psychopharmacotherapy with MED, patients experienced a very significant (97, 19%) and significant improvement (354, 68%) of their mental state, less often the improvement was regarded as minimal (67, 13%). Therefore, almost all patients showed a stable relief of MD; in 87% (95% CI 84-90) of patients, this improvement was significant.

CONCLUSION

The tactics of treatment MD that manifest in patients with HM with MED of psychotropic drugs turned out to be therapeutically effective according to the results of the assessment on CGI scales.

Joint population pharmacokinetic modeling of venlafaxine and O-desmethyl venlafaxine in healthy volunteers and patients to evaluate the impact of morbidity and concomitant medication

Introduction: Venlafaxine (VEN) is a widely used dual selective serotonin/noradrenaline reuptake inhibitor indicated for depression and anxiety. It undergoes first-pass metabolism to its active metabolite, O-desmethyl venlafaxine (ODV). The aim of the present study was to develop a joint population pharmacokinetic (PPK) model to characterize their pharmacokinetic characters simultaneously. Methods: Plasma concentrations with demographic and clinical data were derived from a bioequivalence study in 24 healthy subjects and a naturalistic TDM setting containing 127 psychiatric patients. A parent-metabolite PPK modeling was performed with NONMEM software using a non-linear mixed effect modeling approach. Goodness of fit plots and normalized prediction distribution error method were used for model validation. Results and conclusion: Concentrations of VEN and ODV were well described with a one-compartment model incorporating first-pass metabolism. The first-pass metabolism was modeled as a first-order conversion. The morbid state and concomitant amisulpride were identified as two significant covariates affecting the clearance of VEN and ODV, which may account for some of the variations in exposure. This model may contribute to the precision medication in clinical practice and may inspire other drugs with pre-system metabolism.

[Therapeutic drug monitoring of antidepressants: Why venlafaxine is the most monitored drug? A review of literature]

Venlafaxine is the third most frequently prescribed antidepressant in France the last decade, with about 400,000 daily doses. Therapeutic drug monitoring (TDM) of this medication, by measuring the active moiety venlafaxine (V) and O-desmethylvenlafaxine (ODV), is recommended (level of recommendation 2). However, this antidepressant seems to be the one for which clinicians most often use TDM, much more frequently than escitalopram, which is more prescribed and for which TDM is also recommended. The main goal of this review is to provide an update on the TDM of venlafaxine: its therapeutic interval, its level of recommendation and the origin of its "success". From the literature does not enable to define a therapeutic interval for the active moiety V+ODV, that is to say a steady-state trough concentration allowing a clinical response without toxicity. Nevertheless, a target concentration from 100 to 400μg/L is certainly relevant for the majority of patients without any pharmacodynamic resistance ; though a greater concentration could result in an earlier response or could be required for a clinical response in a minority of patients. A patient with no clinical response despite a concentration greater than 1000μg/L should be proposed another antidepressant. Measurement of the ODV/V ratio is also a useful tool, values below 0.3 usually reflecting a slow metabolizer phenotype for cytochrome P-450 2D6, which is more at risk of adverse effects. Research for this phenotype probably explains many prescriptions for TDM.

In Vitro and In Vivo Rat Model Assessments of the Effects of Vonoprazan on the Pharmacokinetics of Venlafaxine

Purpose

The purpose of the present study was to investigate the effects of vonoprazan on the pharmacokinetics of venlafaxine in vitro and in vivo.

Methods

The mechanism underlying the inhibitory effect of vonoprazan on venlafaxine was investigated using rat liver microsomes. In vitro, the inhibition was evaluated by determining the production of O-desmethylvenlafaxine. Eighteen male Sprague–Dawley rats were randomly divided into three groups: control group, vonoprazan (5 mg/kg) group, and vonoprazan (20 mg/kg) group. A single dose of 20 mg/kg venlafaxine was administrated to rats orally without or with vonoprazan. Plasma was prepared from blood samples collected via the tail vein at different time points and concentrations of venlafaxine and its metabolite, O-desmethylvenlafaxine, were determined by ultra-performance liquid chromatography-tandem mass spectrometry.

Results

We observed that vonoprazan could significantly decrease the amount of O-desmethylvenlafaxine (IC₅₀ = 5.544 μM). Vonoprazan inhibited the metabolism of venlafaxine by a mixed inhibition, combining competitive and non-competitive inhibitory mechanisms. Compared with that in the control group (without vonoprazan), the pharmacokinetic parameters of venlafaxine and its metabolite, O-desmethylvenlafaxine, were significantly increased in both 5 and 20 mg/kg vonoprazan groups, with an increase in MR_{O-desmethylvenlafaxine}.

Conclusion

Vonoprazan significantly alters the pharmacokinetics of venlafaxine in vitro and in vivo. Further investigations should be conducted to check these effects in humans. Therapeutic drug monitoring of venlafaxine in individuals undergoing venlafaxine maintenance therapy is recommended when vonoprazan is used concomitantly.

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.

Effect of venlafaxine dosage, valproic acid concentration, sex, and age on steady state dose-corrected concentrations of venlafaxine and O-desmethylvenlafaxine: A retrospective analysis of therapeutic drug monitoring data in a Chinese population

PURPOSE

This study aimed to investigate the influence of diagnosis, body weight, sex, age, smoking, formulations, and concomitant drugs on steady-state dose-corrected serum concentrations (C/D) of venlafaxine (VEN) and O-desmethylvenlafaxine (ODV).

METHODS

A retrospective analysis of therapeutic drug monitoring (TDM) was carried out. Patients' demographic data, therapeutic regimens, and concentrations were collected.

RESULTS

We included 91 verified samples from 80 patients. Females had by average 13% smaller body weight, 50% higher C/D of VEN, and VEN + ODV and 25% smaller ODV/VEN than males. Patients >60 years had by average 33-59% higher C/D levels of ODV and VEN + ODV than younger patients. The concomitant use of valproic acid caused an average 51% higher C/D of ODV and a 2.2-fold larger ODV/VEN, while clozapine was related with 40% smaller ratio of ODV/VEN and 38% lower C/D levels of ODV. Positive correlations were detected between valproic acid concentrations and the C/D of VEN and VEN + ODV. In a multiple linear regression analysis, variance in the C/D of VEN + ODV was partly attributed to the daily dose of VEN, sex, age and valproic acid concentration.

CONCLUSION

Our results suggested daily dose of VEN, sex, age, and valproic acid as indicators for the C/D of VEN + ODV in Chinese patients. TDM as a valuable tool was suggested in elderly female patients and patients receiving polypharmacy.