Is Therapeutic Drug Monitoring Relevant for Antidepressant Drug Therapy? Implications From a Systematic Review and Meta-Analysis With Focus on Moderating Factors

How to Determine a Therapeutic Reference Range for a Psychotropic Drug Systematically? Recommendations of the TDM Task Force of the AGNP

BACKGROUND

Therapeutic drug monitoring (TDM) is essential for controlling pharmacogenetic and pharmacokinetic variations and for optimizing pharmacotherapy. However, its value is often underestimated because of nonsystematic recommendations for target ranges in the literature. The purpose of this study was to emphasize transparency and systematization in the forthcoming Updates to the Arbeitsgemeinschaft für Neuropsychopharmakologie und Pharmakopsychiatrie (AGNP)-TDM Consensus Guidelines.

METHODS

Here, a stepwise method for determining therapeutic reference ranges (TRRs) in psychiatry is introduced. By using various data types, a multidimensional approach for establishing a range is presented. The data types were classified based on how effectively they supported the target ranges. This method was demonstrated for 3 drugs commonly used in psychiatry (aripiprazole, olanzapine, and escitalopram).

RESULTS

Despite the methodological shortcomings in published concentration-effect studies, the approach used here enabled the determination of reference ranges by combining multiple types of data. The lower limit of the TRR is ideally derived from studies that link blood drug concentrations to clinical effectiveness, particularly symptom-specific responses, after fixed-dose treatment. The upper limit depends on the concentrations associated with adverse reactions or maximal response. Thresholds can be estimated using receiver operating characteristic analyses. Preliminary thresholds were derived from responder concentration data or from expected drug concentrations under approved doses. Positron emission tomography studies were used to further validate these ranges.

CONCLUSIONS

This study proposed a new standard for determining the TRR of psychotropic drugs, thereby enhancing their clinical utility and validity. Adjusting blood levels to these ranges should improve response rates and medication tolerance.

An update on the pharmacotherapy of postpartum depression

Extensive research has been conducted on postpartum depression (PPD) over the past century, and yet no definitive answer regarding its etiopathogenesis, risk factors, genetic predilection, and treatment has been found. The few preclinical and clinical studies propose that maternal brain adaptations to the endocrinological, immunological, and behavioral changes and external sociodemographic risk factors in the perinatal period make women more vulnerable to anxiety and depression. Irrespective of the cause, a dilemma exists regarding the type of help to provide postpartum mothers. With very few treatment options at our disposal, deciding between psychotherapy, pharmacological, and non-pharmacological therapy on a case-by-case basis is unproductive because in developing countries infrastructure is limited and the availability of medications, especially for psychiatric illnesses, is still evolving. Hence, regardless of psychotherapy, antidepressants remain the first line of treatment with selective serotonin reuptake inhibitors (SSRIs); sertraline has the best efficacy and safety profile in breastfeeding women. As endocrine factors play a significant role in etiopathogenesis, hormonal therapy with oxytocin has been shown to be efficacious, and studies investigating the role of testosterone in treating PPD are also under way. In 2019, the US Food and Drug Administration (FDA) approved the first and only drug for the sole purpose of treating PPD, brexanolone. Zuranolone, a drug recently approved by the FDA, has a similar mechanism of action to brexanolone. For breastfeeding mothers reluctant to use pharmacotherapy, somatic therapy has been studied, including bright light therapy, vagal nerve stimulation, and newer noninvasive interventions. This article encompasses a short note on PPD, including its etiopathogenesis and clinical characteristics, and recapitulates the various available and evolving pharmacological and nonpharmacological therapies.

High-performance liquid chromatography-tandem mass spectrometry was used to measure 20 antidepressants in human serum

Aim: This study used high performance liquid chromatography-tandem mass spectrometry to quantify the blood concentrations of 20 antidepressants, such as bupropion and fluoxetine, in human serum samples.Methods: After direct precipitation with a 1:9 protein precipitant of methanol and acetonitrile, serum samples were examined using high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS). The material was separated using a Poroshell 120 EC-C18 column (3.0 mm × 50 mm, 2.7 μm) and gradient elution. The mobile phases were phase A 0.01% formic acid aqueous solution (containing 2 mmol/ml ammonium acetate) and phase B methanol solution. A 0.45 ml/min flow rate was used to divide the sample and inject 5 μl. Electrospray ionization source positive ion mode and multiple reaction monitoring modes were used for analysis. Measurement was quantified using an internal standard technique.Results: Accuracy ranged from 90.3 to 114.3%, intra-day precision from 100.1 to 112.3%, inter-day precision from 100.4 to 112.6%, extraction recoveries from 85.5 to 114.5% and matrix effect from 85.6 to 98.7%.Conclusion: This approach is fast, accurate, sensitive and repeatable. It can identify 20 antidepressants in blood simultaneously. This can be used to monitor blood drug levels and medication metabolism.

Association of CYP2D6 and CYP2C19 metabolizer status with switching and discontinuing antidepressant drugs: an exploratory study

BACKGROUND

Tailoring antidepressant drugs (AD) to patients' genetic drug-metabolism profile is promising. However, literature regarding associations of ADs' treatment effect and/or side effects with drug metabolizing genes CYP2D6 and CYP2C19 has yielded inconsistent results. Therefore, our aim was to longitudinally investigate associations between CYP2D6 (poor, intermediate, and normal) and CYP2C19 (poor, intermediate, normal, and ultrarapid) metabolizer-status, and switching/discontinuing of ADs. Next, we investigated whether the number of perceived side effects differed between metabolizer statuses.

METHODS

Data came from the multi-site naturalistic longitudinal cohort Netherlands Study of Depression and Anxiety (NESDA). We selected depression- and/or anxiety patients, who used AD at some point in the course of the 9 years follow-up period (n = 928). Medication use was followed to assess patterns of AD switching/discontinuation over time. CYP2D6 and CYP2C19 alleles were derived using genome-wide data of the NESDA samples and haplotype data from the PharmGKB database. Logistic regression analyses were conducted to investigate the association of metabolizer status with switching/discontinuing ADs. Mann-Whitney U-tests were conducted to compare the number of patient-perceived side effects between metabolizer statuses.

RESULTS

No significant associations were observed of CYP metabolizer status with switching/discontinuing ADs, nor with the number of perceived side effects.

CONCLUSIONS

We found no evidence for associations between CYP metabolizer statuses and switching/discontinuing AD, nor with side effects of ADs, suggesting that metabolizer status only plays a limited role in switching/discontinuing ADs. Additional studies with larger numbers of PM and UM patients are needed to further determine the potential added value of pharmacogenetics to guide pharmacotherapy.

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.

Treatment-resistant depression: definition, prevalence, detection, management, and investigational interventions

Treatment-resistant depression (TRD) is common and associated with multiple serious public health implications. A consensus definition of TRD with demonstrated predictive utility in terms of clinical decision-making and health outcomes does not currently exist. Instead, a plethora of definitions have been proposed, which vary significantly in their conceptual framework. The absence of a consensus definition hampers precise estimates of the prevalence of TRD, and also belies efforts to identify risk factors, prevention opportunities, and effective interventions. In addition, it results in heterogeneity in clinical practice decision-making, adversely affecting quality of care. The US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) have adopted the most used definition of TRD (i.e., inadequate response to a minimum of two antidepressants despite adequacy of the treatment trial and adherence to treatment). It is currently estimated that at least 30% of persons with depression meet this definition. A significant percentage of persons with TRD are actually pseudo-resistant (e.g., due to inadequacy of treatment trials or non-adherence to treatment). Although multiple sociodemographic, clinical, treatment and contextual factors are known to negatively moderate response in persons with depression, very few factors are regarded as predictive of non-response across multiple modalities of treatment. Intravenous ketamine and intranasal esketamine (co-administered with an antidepressant) are established as efficacious in the management of TRD. Some second-generation antipsychotics (e.g., aripiprazole, brexpiprazole, cariprazine, quetiapine XR) are proven effective as adjunctive treatments to antidepressants in partial responders, but only the olanzapine-fluoxetine combination has been studied in FDA-defined TRD. Repetitive transcranial magnetic stimulation (TMS) is established as effective and FDA-approved for individuals with TRD, with accelerated theta-burst TMS also recently showing efficacy. Electroconvulsive therapy is regarded as an effective acute and maintenance intervention in TRD, with preliminary evidence suggesting non-inferiority to acute intravenous ketamine. Evidence for extending antidepressant trial, medication switching and combining antidepressants is mixed. Manual-based psychotherapies are not established as efficacious on their own in TRD, but offer significant symptomatic relief when added to conventional antidepressants. Digital therapeutics are under study and represent a potential future clinical vista in this population.

Low Escitalopram Concentrations in Patients with Depression predict Treatment Failure: A Naturalistic Retrospective Study

INTRODUCTION

Cross sectional therapeutic drug monitoring (TDM) data mining introduces new opportunities for the investigation of medication treatment effects to find optimal therapeutic windows. Medication discontinuation has been proven useful as an objective surrogate marker to assess treatment failure. This study aimed to investigate the treatment effects of escitalopram and pharmacokinetic influences on blood levels using retrospectively assessed data from a TDM database.

METHODS

Data was collected from 134 patients longitudinally treated with escitalopram for whom TDM was requested to guide drug therapy. Escitalopram metabolism was estimated by the log-transformed dose-corrected concentrations and compared within subpopulations differing in age, gender, renal function, smoking status, body mass index, and comedication.

RESULTS

Patients with a depressive episode who were treated with escitalopram and discontinued the treatment within the hospital stay showed lower serum concentrations compared to patients who continued escitalopram treatment with a concentration of 15 ng/mL separating both groups. Variability was high between individuals and factors influencing blood levels, including dose, sex, and age. Comedication that inhibits cytochrome P450 (CYP) 2C19 isoenzymes were further found to influence escitalopram pharmacokinetics independent of dose, age or sex.

DISCUSSION

Medication switch is a valuable objective surrogate marker to assess treatment effects under real-world conditions. Of note, treatment discontinuation is not always a cause of insufficient response but may also be related to other factors such as medication side effects. TDM might not only be useful in addressing these issues but titrating drug concentrations into the currently recommended reference range for escitalopram will also increase response in non-responders and avoid treatment failure in underdosed patients.

Toward therapeutic drug monitoring of citalopram in depression? Insights from a systematic review

Background

Within the framework of individualized psychopharmacotherapy, therapeutic drug monitoring (TDM) has gained increasing relevance. In the absence of high-quality evidence, the TDM of citalopram (CIT) and the recommended therapeutic ranges of the plasma concentrations have been proposed by guidelines. However, the correlation between the plasma concentration of CIT and treatment outcomes has not been well established. Therefore, the aim of this systematic review was to evaluate the relationship between plasma CIT concentration and treatment outcomes in depression.

Research design and methods

PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and Chinese databases (CNKI, Wanfang Data and Sinomed) were searched up to August 6, 2022. We included clinical studies evaluating the correlation between the plasma CIT concentration and treatment outcomes in patients with depression receiving CIT treatment. Outcomes measured included efficacy, safety, medication adherence, and cost-related outcomes. A narrative synthesis was performed to summarize findings from individual studies. This study was performed according to the Preferred Reporting Items for Systematic Reviews, Meta-Analysis (PRISMA) and the reporting guideline for Synthesis without meta-analysis (SWiM).

Results

Eleven studies involving 538 patients were included in total. The reported outcomes were mainly efficacy (n = 11) and safety (n = 3); one study reported the duration of hospitalization, and no study reported medication adherence. Regarding the efficacy outcomes, three studies revealed the plasma CIT concentration-response relationship and proposed a lower limit of 50 or 53 ng/mL, whereas this was not found in the rest of the studies. Regarding adverse drug events (ADEs), one study reported more ADEs in the low-concentration group (<50 ng/mL vs. >50 ng/mL), which is not convincing from the perspective of pharmacokinetics/pharmacodynamics. Regarding the cost-related outcomes, only one study reported that the high CIT concentration group (≥50 ng/mL) contributed to shortening the hospitalization duration, but it did not provide detailed information, including direct medical expenses and multiple potential factors contributing to longer hospital stays.

Conclusions

A definite correlation between plasma concentration and clinical or cost-related outcomes of CIT cannot be drawn, whereas a tendency toward improved efficacy in patients with plasma concentration above 50 or 53 ng/mL was suggestive from limited evidence.

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.

Analysis of Antidepressants Utilization for Patients Visiting Psychiatric Out-Patient Clinic in a Tertiary Care Hospital

Depression is a prevalent mental health condition treated with antidepressants and other psychotropic medications. This study aimed to assess the utilization pattern of antidepressants among patients visiting the outpatient clinic of the psychiatry department of a tertiary care hospital. The study included the patients who visited the study site and fulfilled the mental and behavioral diagnostic criteria for depression. The demographic and clinical details, including drugs prescribed, were documented in a study-specific data collection form. The ratio of Prescribed Daily Dose to Defined Daily Dose (PDD: DDD) was calculated to assess the adequacy of antidepressant utilization. Data total of 154 patients were collected. A total of 22 psychotropic drugs were used among the study patients as mono (n = 70), dual (n = 69), triple (n = 10), or quadruple therapy (n = 1). Escitalopram was the most often prescribed antidepressant out of the nine antidepressants alone and in combination and was used in slightly high doses (PDD: DDD ratio 1.6). Sertraline, paroxetine, and desvenlafaxine, were used in adequate doses (PDD: DDD between 1 and 1.1), and fluoxetine, duloxetine, amitriptyline, imipramine, and mirtazapine, were used in inadequate doses (PDD: DDD <0.5). Our study findings reveal the need for continuous assessment of antidepressants medications usage in a hospital set up.