Sex and body weight are major determinants of venlafaxine pharmacokinetics

Pharmacokinetic correlates of clinical response in a naturalistic sample of escitalopram-treated patients

OBJECTIVE

We assessed pharmacokinetic correlates of treatment response to escitalopram using a large therapeutic drug monitoring database.

METHODS

A large naturalistic sample of patients receiving escitalopram was analyzed. Responders were defined as 'very much improved' or 'much improved' based on the Clinical Global Impression - Improvement score, CGI-I. We compared responders (n = 83) vs. non-responders (n = 388) with the primary outcome being the escitalopram plasma concentration and concentration corrected by the daily dose (C/D ratio). Effects of age, sex, body-mass-index (BMI), and C/D ratio were assessed in a multivariate logistic regression model predicting response.

RESULTS

There were no statistically significant differences in clinical and demographic characteristics between responders vs. non-responders. There were also no differences between escitalopram daily doses or plasma concentrations, while C/D ratios were significantly higher in non-responders than in responders (1.6 ± 1.7 vs. 1.2 ± 0.9 (ng/mL)/(mg/day), p = 0.007); C/D ratios (odds ratio 0.52, 95% confidence interval 0.34-0.80, p < 0.003) were associated with response to escitalopram, after controlling for age, sex, and BMI.

CONCLUSIONS

Patients with low clearance of escitalopram as reflected upon high C/D ratios may be less likely respond to escitalopram. Identifying these patients during dose titration may support clinical decision-making, including switching to a different antidepressant instead of increasing daily dose.

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.

Effects of Sleeve Gastrectomy and Roux-en-Y Gastric Bypass on Escitalopram Pharmacokinetics: A Cohort Study

BACKGROUND

Changes in the gastrointestinal physiology after bariatric surgery may affect the pharmacokinetics of medications. Data on the impact of different surgical techniques on the pharmacokinetics of commonly prescribed antidepressants such as escitalopram are limited.

METHODS

This case-only prospective study investigated escitalopram-treated patients who underwent bariatric surgery at hospitals in Central Norway. Escitalopram concentrations were assessed using serial blood samples obtained during a dose interval of 24 hours preoperatively and at 1, 6, and 12 months, postoperatively. The primary outcomes were changes in the area under the time-concentration curve (AUC 0-24 ) with secondary outcomes, including full pharmacokinetic profiling. We performed repeated-measures analysis of variance for the AUC 0-24 and secondary outcomes.

RESULTS

Escitalopram-treated obese patients who underwent sleeve gastrectomy (n = 5) and Roux-en-Y gastric bypass (n = 4) were included. Compared with preoperative baseline, dose-adjusted AUC 0-24 values were within ±20% at all time points, postoperatively in the sleeve gastrectomy and oux-en-Y gastric bypass groups, with the largest changes occurring 1 month postoperatively (+14.5 and +17.2%, respectively). No statistically significant changes in any pharmacokinetic variables over time were reported; however, there was a trend toward increased maximum concentrations after surgery ( P = 0.069).

CONCLUSIONS

Our findings suggest that bariatric surgery has no systematic effect on the pharmacokinetics of escitalopram. However, because of the substantial interindividual variation, therapeutic drug monitoring can be considered to guide postoperative dose adjustments.

Current Status of Therapeutic Drug Monitoring in Mental Health Treatment: A Review

Therapeutic drug monitoring (TDM) receives growing interest in different psychiatric clinical settings (emergency, inpatient, and outpatient services). Despite its usefulness, TDM remains underemployed in mental health. This is partly due to the need for evidence about the relationship between drug serum concentration and efficacy and tolerability, both in the general population and even more in subpopulations with atypical pharmacokinetics. This work aims at reviewing the scientific literature published after 2017, when the most recent guidelines about the use of TDM in mental health were written. We found 164 pertinent records that we included in the review. Some promising studies highlighted the possibility of correlating early drug serum concentration and clinical efficacy and safety, especially for antipsychotics, potentially enabling clinicians to make decisions on early laboratory findings and not proceeding by trial and error. About populations with pharmacokinetic peculiarities, the latest studies confirmed very common alterations in drug blood levels in pregnant women, generally with a progressive decrease over pregnancy and a very relevant dose-adjusted concentration increase in the elderly. For adolescents also, several drugs result in having different dose-related concentration values compared to adults. These findings stress the recommendation to use TDM in these populations to ensure a safe and effective treatment. Moreover, the integration of TDM with pharmacogenetic analyses may allow clinicians to adopt precise treatments, addressing therapy on an individual pharmacometabolic basis. Mini-invasive TDM procedures that may be easily performed at home or in a point-of-care are very promising and may represent a turning point toward an extensive real-world TDM application. Although the highlighted recent evidence, research efforts have to be carried on: further studies, especially prospective and fixed-dose, are needed to replicate present findings and provide clearer knowledge on relationships between dose, serum concentration, and efficacy/safety.

Effects of body weight, smoking status, and sex on plasma concentrations of once-monthly paliperidone palmitate

OBJECTIVES

Knowledge about the impact of body composition features on pharmacokinetics of newer long-acting injectable antipsychotics is limited.

METHODS

We analyzed steady-state plasma concentrations of paliperidone in different body mass index (BMI), age, sex, and smoking status patient subgroups treated with once-monthly paliperidone palmitate (PP1M). Paliperidone plasma concentrations and dose-adjusted-plasma concentrations (C/D) from a therapeutic drug monitoring (TDM) database of PP1M-treated patients were compared among normal BMI, overweight, and obese patients as well as between females vs. males, elderly vs. non-elderly, and smokers vs. non-smokers using non-parametric tests.

RESULTS

In a total of 183 PP1M-treated patients, we found highly variable paliperidone plasma concentrations between individuals but no significant effect of PP1M dose or dosing intervals (p> 0.05). C/D ratios were similar in 54 obese, 82 overweight, and 47 normal BMI patients (p> 0.05). Females had 13.7% higher C/D ratios compared to males, yet this difference was not significant (p> 0.05). No differences were found between elderly vs. non-elderly patients or for smokers vs. non-smokers (p> 0.05).

CONCLUSION

Our findings suggest that age, sex, smoking, or body weight may not substantially affect pharmacokinetic indices of PP1M. The high interindividual variation of plasma concentrations implies that TDM may be helpful to enhance PP1M efficacy and tolerability.

Impact of Body Mass Index on Serum Concentrations of Antidepressants and Antipsychotics

BACKGROUND

Rates of overweight and obesity are higher in patients suffering from psychiatric disorders than in the general population. Body composition and enzyme functions are affected by overweight, and consequently, the pharmacokinetics of drugs may vary in overweight patients. Thus, overweight and obesity are important factors in psychiatric disorders and their treatment. This analysis aimed to investigate the impact of body mass index (BMI) on serum concentrations of the antidepressant drugs amitriptyline, doxepin, escitalopram, mirtazapine, and venlafaxine, and the antipsychotic drugs clozapine, quetiapine, and risperidone, taking into account the following confounding parameters: age, sex, and smoking habit.

METHODS

Inpatients and outpatients (N = 1657) who took at least one of the target drugs were included in this retrospective analysis. Serum concentrations of the target drugs and their metabolites were determined at the Department of Psychiatry, Psychosomatics, and Psychotherapy of the University Hospital of Würzburg during routine therapeutic drug monitoring (January 2009-December 2010), which was performed in the morning (trough level) at steady state.

RESULTS

Dose-corrected serum concentrations (CD) of the active moiety of doxepin and venlafaxine and of O-desmethylvenlafaxine were negatively associated with BMI (partial Pearson correlation, R = -0.267, P = 0.002; R = -0.206, P ≤ 0.001; R = -0.258, P ≤ 0.001), and the CDs were different in normal weight, overweight, and obese patients (analysis of covariance, P = 0.004, P < 0.001, P ≤ 0.001). No association was found between BMI and serum concentrations of amitriptyline, escitalopram, mirtazapine, clozapine, quetiapine, and risperidone.

CONCLUSIONS

In obese patients, higher doses of doxepin and venlafaxine are necessary to achieve similar serum concentrations as in normal weight patients and to avoid treatment-resistant depression.

Body mass index as a determinant of clozapine plasma concentrations: A pharmacokinetic-based hypothesis

BACKGROUND

Knowledge regarding the impact of body composition measures on pharmacokinetics of antipsychotics is limited.

AIMS

Our aim was to investigate the impact of body weight and body mass index on clozapine pharmacokinetics using a therapeutic drug monitoring database.

METHODS

A large therapeutic drug monitoring dataset of clozapine plasma concentrations considering three patient subgroups was analysed: a control group (CLZ₀, 20-30 kg/m², n=266), a group with high body mass index (CLZ_high, body mass index ⩾30 kg/m², n=162) and with low body mass index values (CLZ_low, body mass index <20 kg/m², n=27). Comparisons of plasma and dose-adjusted plasma concentrations (C/D) of clozapine were based on the Spearman's correlation (rs), Kruskal Wallis and Mann-Whitney-U tests. For percentages we used the Pearson chi-square test (χ²). To assess effects of confounders we used bootstrapping analysis of covariates.

RESULTS/OUTCOMES

Regarding demographic characteristics, groups differed only for sex percentage with more females than males in CLZ_low and CLZ_high compared to CLZ₀ (p=0.001 for χ² test). Plasma and C/D values were positively associated with body mass index (rs=0.108, p=0.022 and rs=0.156, p=0.001 respectively). Intergroup differences were observed for plasma and dose-adjusted concentrations of clozapine (p=0.031 and p=0.029 for Kruskal Wallis respectively): post-hoc pairwise comparisons showed higher plasma concentrations and C/D of clozapine in CLZ_high compared to CLZ₀ (p=0.014 and p=0.007 respectively for Mann-Whitney U-test), by mean 21 and 18%, respectively. Differences for C/D values remained after accounting for sex (p=0.02).

CONCLUSIONS/INTERPRETATION

In obese patients, bioavailability, distribution or elimination of clozapine may be altered due to increased clozapine deposits in fat tissue and hepatic enzyme activity changes.

The effect of obesity, macronutrients, fasting and nutritional status on drug-metabolizing cytochrome P450s: a systematic review of current evidence on human studies

BACKGROUND

Cytochrome P450s (CYPs) are a class of hemoproteins involved in drug metabolism. It has been reported that body composition, proportion of dietary macronutrients, fasting and nutritional status can interfere with the activity of drug-metabolizing CYPs.

OBJECTIVES

The present systematic review was conducted to summarize the effect of obesity, weight reduction, macronutrients, fasting and malnutrition on the CYP-mediated drug metabolism.

METHODS

PubMed (Medline), Scopus, Embase and Cochrane Library databases and Google Scholar were searched up to June 2020 to obtain relevant studies. The PRISMA guidelines were employed during all steps. Two reviewers independently extracted the information from the included studies. Studies investigating CYPs activity directly or indirectly through pharmacokinetics of probe drugs, were included. Increase in clearance (CL) or decrease in elimination half-life (t½) and area under the curve (AUC) of probe drugs were considered as increase in CYPs activity.

RESULTS

A total of 6545 articles were obtained through searching databases among which 69 studies with 126 datasets fully met the inclusion criteria. The results indicated that obesity might decrease the activity of CYP3A4/5, CYP1A2 and CYP2C9 and increase the activity of CYP2E1. The effect of obesity on CYP2D6 is controversial. Also, weight loss increased CYP3A4 activity. Moreover, CYP1A2 activity was decreased by high carbohydrate diet, increased by high protein diet and fasting and unchanged by malnutrition. The activity of CYP2C19 was less susceptible to alterations compared to other CYPs.

CONCLUSION

The activity of drug-metabolizing CYPs are altered by body composition, dietary intake and nutritional status. This relationship might contribute to drug toxicity or reduce treatment efficacy and influence cost-effectiveness of medical care.

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.

Pharmacokinetic correlates of venlafaxine: associated adverse reactions

To address the potential correlation between plasma concentrations of venlafaxine (VEN), its active metabolite O-desmethylvenlafaxine (ODVEN) and the active moiety, AM, (ODVEN + VEN) and adverse drug reactions (ADR) in a large naturalistic sample of in- and outpatients. We compared plasma concentrations of VEN, ODVEN and AM and dose-adjusted (C/D) levels as well the ODVEN/VEN ratios between patients complaining ADRs, following the Udvalg for Kliniske Undersogelser side effect rating scales (UKU) (n = 114) and patients without ADRs (control group, n = 688) out of a naturalistic database. We also investigated potential pharmacokinetic correlates of the four UKU categories by comparing patients complaining ADRs with those who did not. Based on previous literature we applied different ODVEN/VEN ratio values as cut-offs to split our sample into two groups at a time and compare frequencies of ADRs between the groups. No differences for demographic and pharmacokinetic variables including plasma and C/D concentrations as well as ODVEN/VEN ratios were observed between study groups. Neither the comparisons between females and males nor between elderly and non-elderly patients revealed significant differences (p > 0.05 in all cases). No differences were also reported exploring the patients complaining ADRs from the 4 UKU categories separately. After applying various ODVEN/VEN cut-offs, groups did not display differences in frequencies of ADRs (p > 0.05 in all cases). Our findings do not demonstrate a direct link between venlafaxine metabolism measures and ADRs. Therefore, additional dimensions are needed to be considered in future trials aiming to disentangle the involved aspects of ADRs in patients receiving venlafaxine.