Therapeutic monitoring of psychoactive drugs - antidepressants: A review

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.

Influence of antidepressant drugs on DNA methylation of ion channels genes in blood cells of psychiatric patients

Aim: This study investigated the influence of antidepressant drugs on methylation status of KCNE1, KCNH2 and SCN5A promoters and ECG parameters in adult psychiatric patients. Materials & methods: Electrocardiographic evaluation (24 h) and blood samples were obtained from 34 psychiatric patients before and after 30 days of antidepressant therapy. Methylation of promoter CpG sites of KCNE1, KCNH2 and SCN5A was analyzed by pyrosequencing. Results: Three CpG and four CpG sites of KCNE1 and SCN5A, respectively, had increased % methylation after treatment. Principal component analysis showed correlations of the methylation status with electrocardiographic variables, antidepressant doses and patient age. Conclusion: Short-term treatment with antidepressant drugs increase DNA methylation in KCNE1 and SCN5A promoters, which may induce ECG alterations in psychiatric patients.

The role of cytochromes P450 in metabolism of selected antidepressants and anxiolytics under psychological stress

In today's modern society, it seems to be more and more challenging to cope with life stresses. The effect of psychological stress on emotional and physical health can be devastating, and increased stress is associated with increased rates of heart attack, hypertension, obesity, addiction, anxiety and depression. This review focuses on the possibility of an influence of psychological stress on the metabolism of selected antidepressants (TCAs, SSRIs, SNRIs, SARIs, NDRIs a MMAs) and anxiolytics (benzodiazepines and azapirone), as patients treated with antidepressants and/or anxiolytics can still suffer from psychological stress. Emphasis is placed on the drug metabolism mediated by the enzymes of Phase I, typically cytochromes P450 (CYPs), which are the major enzymes involved in drug metabolism, as the majority of psychoactive substances are metabolized by numerous CYPs (such as CYP1A2, CYP2B6, CYP2C19, CYP2C9, CYP2A6, CYP2D6, CYP3A4). As the data on the effect of stress on human enzymes are extremely rare, modulation of the efficacy and even regulation of the biotransformation pathways of drugs by psychological stress can be expected to play a significant role, as there is increasing evidence that stress can alter drug metabolism, hence there is a risk of less effective drug metabolism and increased side effects.

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

Inter-individual differences in antidepressant drug concentrations attained in blood may limit the efficacy of pharmacological treatment of depressive disorders. Therapeutic drug monitoring (TDM) enables to determine drug concentrations in blood and adjust antidepressant dosage accordingly. However, research on the underlying assumption of TDM, association between concentration and clinical effect, has yielded ambiguous results for antidepressants. It has been proposed that this ambiguity may be caused by methodological shortcomings in studies investigating the concentration-effect relationship. Guidelines recommend the use of TDM in antidepressant treatment as expert opinion. This reflects the lack of research, particularly systematic reviews and meta-analyses of randomized controlled trials, on the relationship between concentration and effect as well as on the benefits of the use of TDM in clinical practice. In this study, a systematic review and meta-analysis of randomized controlled trials has been performed to investigate the relationship between antidepressant concentration, efficacy, and side effects. It is the first meta-analytical approach to this subject and additionally considers methodological properties of primary studies as moderators of effect in quantitative analysis. Our results identified methodological shortcomings, namely the use of a flexible dose design and the exclusion of concentrations in lower- or subtherapeutic ranges, which significantly moderate the relationship between antidepressant concentration and efficacy. Such shortcomings obscure the evidence base of using TDM in clinical practice to guide antidepressant drug therapy. Further research should consider these findings to determine the relationship between concentration and efficacy and safety of antidepressant treatments, especially for newer antidepressants.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=246149, identifier: CRD42021246149.

Chronopharmacology in Therapeutic Drug Monitoring-Dependencies between the Rhythmics of Pharmacokinetic Processes and Drug Concentration in Blood

The objective of the optimization of pharmacotherapy compliant with the basic rules of clinical pharmacology is its maximum individualization, ensuring paramount effectiveness and security of the patient's therapy. Thus, multiple factors that are decisive in terms of uniqueness of treatment of the given patient must be taken into consideration, including, but not limited to, the patient's age, sex, concomitant diseases, special physiological conditions (e.g., pregnancy, lactation, extreme age groups), polypharmacotherapy and polypragmasia (particularly related to increased risk of drug interactions), and patient's phenotypic response to the administered drug with possible genotyping. Conducting therapy while monitoring the concentration of certain drugs in blood (Therapeutic Drug Monitoring; TDM procedure) is also one of the factors enabling treatment individualization. Furthermore, another material, and yet still a marginalized pharmacotherapeutic factor, is chronopharmacology, which indirectly determines the values of drug concentrations evaluated in the TDM procedure. This paper is a brief overview of chronopharmacology, especially chronopharmacokinetics, and its connection with the clinical interpretation of the meaning of the drug concentrations determined in the TDM procedure.

Thin film molecularly imprinted polymer (TF-MIP), a selective and single-use extraction device for high-throughput analysis of biological samples

Enhancing selectivity, reducing matrix effects and increasing analytical throughput have been the main objectives in the development of biological sample preparation techniques. A thin film molecularly imprinted polymer (MIP) is employed for extraction and analysis of tricyclic antidepressants (TCAs) as a model class of compounds in human plasma for the first time to reach the abovementioned goals. The thin film MIPs prepared on a metal substrate can be used directly for extraction from biological matrices with no sample manipulation steps and no pre-conditioning. This method was validated with good linearity (R² > 0.99 in 1.0-500.0 ng mL^-1 range), excellent accuracy (90% -110%) and precision (RSD % value less than 15%) in pooled human plasma samples (N = 3). The limits of quantitation (LOQ) for TCAs in plasma samples were between 1.0-5.0 ng mL^-1 which are lower than the therapeutic ranges of these drugs. Kinetic and isotherm studies showed the superior performance of MIP sorbent compared to a non-imprinted polymer (NIP) sorbent in extracting TCAs from a bovine serum albumin (BSA) solution. The optimized and validated method for pooled human plasma was utilized for monitoring the concentration of TCAs in three patient samples who had been prescribed TCAs. These selective single-use thin film extraction devices are promising for efficient and fast procedures for analyzing biological samples.

Therapeutic Drug Monitoring of Fluoxetine, Norfluoxetine and Paroxetine: A New Tool Based on Microextraction by Packed Sorbent Coupled to Liquid Chromatography

The present article reports the first liquid chromatography (LC) assay for the simultaneous quantification of fluoxetine (FLU), its metabolite norfluoxetine (NFLU) and paroxetine (PAR) in human plasma, applying the microextraction by packed sorbent (MEPS) technology in sample preparation. Chromatographic analysis of FLU, NFLU and PAR was achieved in <13 min on a reverse-phase C18 column using isocratic elution and fluorescence detection (FLD). The mobile phase was composed by an aqueous solution of 25 mM sodium phosphate monobasic anhydrous and 7.5 mM di-potassium hydrogen phosphate anhydrous (pH 3.0)/acetonitrile/methanol (70:23:7, v/v/v). The detector was set at 240/312 nm for FLU, NFLU and IS and at 295/350 nm for PAR. The method showed linearity in the ranges of 20-750 ng mL-1 for FLU and NFLU, and 5-750 ng mL-1 for PAR (r2 ≥ 0.9919). The overall intra- and interday precision did not exceed 13.6% and the corresponding accuracy (bias) ranged from 0.02 to 16.7%. The method was successfully applied in the analysis of authentic plasma samples. Hence, this new MEPS/LC-FLD assay ensures robust and low-cost analyses representing, therefore, a good alternative to support therapeutic drug monitoring and clinical studies involving these antidepressant drugs.

Medication adherence, medical record accuracy, and medication exposure in real-world patients using comprehensive medication monitoring

Background

Poor adherence to medication regimens and medical record inconsistencies result in incomplete knowledge of medication therapy in polypharmacy patients. By quantitatively identifying medications in the blood of patients and reconciling detected medications with the medical record, we have defined the severity of this knowledge gap and created a path toward optimizing medication therapy.

Methods and findings

We validated a liquid chromatography-tandem mass spectrometry assay to detect and/or quantify 38 medications across a broad range of chronic diseases to obtain a comprehensive survey of patient adherence, medical record accuracy, and exposure variability in two patient populations. In a retrospectively tested 821-patient cohort representing U.S. adults, we found that 46% of medications assessed were detected in patients as prescribed in the medical record. Of the remaining medications, 23% were detected, but not listed in the medical record while 30% were prescribed to patients, but not detected in blood. To determine how often each detected medication fell within literature-derived reference ranges when taken as prescribed, we prospectively enrolled a cohort of 151 treatment-regimen adherent patients. In this cohort, we found that 53% of medications that were taken as prescribed, as determined using patient self-reporting, were not within the blood reference range. Of the medications not in range, 83% were below and 17% above the lower and upper range limits, respectively. Only 32% of out-of-range medications could be attributed to short oral half-lives, leaving extensive exposure variability to result from patient behavior, undefined drug interactions, genetics, and other characteristics that can affect medication exposure.

Conclusions

This is the first study to assess compliance, medical record accuracy, and exposure as determinants of real-world treatment and response. Variation in medication detection and exposure is greater than previously demonstrated, illustrating the scope of current therapy issues and opening avenues that warrant further investigation to optimize medication therapy.

A Case Report of Clonazepam Dependence: Utilization of Therapeutic Drug Monitoring During Withdrawal Period

Clonazepam is long-acting benzodiazepine agonist used in short-acting benzodiazepine withdrawal; however, recent observations suggest the existence of its abuse. We demonstrate a 40-year-old man with a 20-year history of psychiatric care with recently benzodiazepine dependence (daily intake of ∼60 mg of clonazepam and 10 mg of alprazolam). High serum levels of both drugs were analyzed 3 weeks before admission to hospitalization (clonazepam 543.9 ng/mL, alprazolam 110 ng/mL) and at the time of admission (clonazepam 286.2 ng/mL, alprazolam 140 ng/mL) without any signs of benzodiazepine intoxication. Gradual withdrawal of clonazepam with monitoring of its serum levels and increase of gabapentin dose were used to minimize physical signs and symptoms of clonazepam withdrawal. Alprazolam was discontinued promptly. Clinical consequences of the treatment were controllable tension, intermittent headache, and rarely insomia. It is the first case report showing utilization of therapeutic drug monitoring during withdrawal period in the patient with extreme toleration to severe benzodiazepine dependence.

Current advances in biosampling for therapeutic drug monitoring of psychiatric CNS drugs

Many CNS drugs are effective for the treatment of psychiatric disorders. Psychotropic drugs work differently, thus clinical outcomes for many patients may be insufficient. For this reason it could be useful the measurement of drug levels for clinical decision-making. Analytical goals in therapeutic drug monitoring (TDM) should be established by selecting the appropriate biological matrix. The aim of this review is to highlight the usefulness of TDM for antiepileptics, antidepressants and antipsychotics, with a focus on current advances in biosampling. The literature on TDM was reviewed up to March 2015. An overview on the use of alternative biological matrices is provided to address the current issues and advances in the field of biosampling for psychiatric CNS drug TDM.