Pharmacokinetics of serotonergic drugs: focus on OCD

Deprescribing Antidepressants in Children and Adolescents: A Systematic Review of Discontinuation Approaches, Cross-Titration, and Withdrawal Symptoms

Background: Antidepressant medications, including selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs), are commonly used to treat depressive, anxiety, and obsessive-compulsive disorders in youth. Yet, data on discontinuing these medications, withdrawal symptoms, and strategies to switch between them are limited. Methods: We searched PubMed and ClinicalTrials.gov through June 1, 2024, to identify randomized controlled trials assessing antidepressant discontinuation in youth. We summarized pediatric pharmacokinetic data to inform tapering and cross-titration strategies for antidepressants and synthesized these data with reports of antidepressant withdrawal. Results: Our search identified 528 published articles, of which 28 were included. In addition, 19 records were obtained through other methods, with 14 included. The corpus of records included 13 randomized, double-blind, placebo-controlled trials (3026 patients), including SSRIs (K = 10), SNRIs (K = 4), and TCAs (K = 1), ranging from 4 to 35 weeks. Deprescribing antidepressants requires considering clinical status, treatment response, and, in cross-titration cases, the pharmacokinetics and pharmacodynamics of both medications. Antidepressant withdrawal symptoms are related to the pharmacokinetics of the medication, which vary across antidepressants and may include irritability, palpitations, anxiety, nausea, sweating, headaches, insomnia, paresthesia, and dizziness. These symptoms putatively involve changes in serotonin transporter expression and receptor sensitivity, impacting the serotonin, dopamine, and norepinephrine pathways. Conclusions: Although approaches to deprescribing antidepressants in pediatric patients are frequently empirically guided, accumulating data related to the course of relapse and withdrawal symptoms, as well as the pharmacokinetic and pharmacodynamic properties of medications, should inform these approaches. Recommendations within this review support data-informed discussions of deprescribing-including when and how-that are critically important in the clinician-family-patient relationship.

Management and Treatment of Obsessive-Compulsive Disorder (OCD): A Literature Review

Obsessive-compulsive disorder (OCD) is a prevalent and debilitating mental health condition. This literature review examines the latest strategies in managing and treating OCD, with an emphasis on psychotherapy, pharmacological interventions, and neurosurgical options. A comprehensive literature search utilizing PubMed, Google Scholar, ClinicalKey, and Embase databases was conducted. Utilizing chosen keywords, the resulting articles were filtered based on inclusion and exclusion criteria. Included articles were used to discuss current research regarding OCD treatment and management. Findings reveal the efficacy and obstacles of treatments such as cognitive-behavioral therapy, selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), and evidence-based neurosurgical methods, offering a broad perspective on OCD management. We discuss the limitations of these established treatments and examine the innovative response of neurosurgery in treating patients with OCD. This review highlights the importance of individualized treatment plans and areas for future research.

Therapeutic drug monitoring of sertraline in children and adolescents: A naturalistic study with insights into the clinical response and treatment of obsessive-compulsive disorder

BACKGROUND

Sertraline is a selective serotonin reuptake inhibitor with specific indications in child and adolescent psychiatry. Notwithstanding its frequent use and clinical benefits, the relationship between pharmacokinetics, pharmacodynamics, efficacy, and tolerability of sertraline across indications, particularly in non-adult patients, is not fully understood.

METHOD

This naturalistic therapeutic drug monitoring (TDM) study was conducted in a transdiagnostic sample of children and adolescents treated with sertraline (n = 78; mean age, 14.22 ± 2.39; range, 7-18 years) within the prospective multicenter "TDM-VIGIL" project. Associations between dose, serum concentration, and medication-specific therapeutic and side effects based on the Clinical Global Impression scale were examined. Tolerability was measured qualitatively with the 56-item Pediatric Adverse Event Rating Scale.

RESULTS

A strong linear positive dose-serum concentration relationship (with dose explaining 45% of the variance in concentration) and significant effects of weight and co-medication were found. Neither dose nor serum concentration were associated with side effects. An overall mild-to-moderate tolerability profile of sertraline was observed. In contrast with the transdiagnostic analysis that did not indicate an effect of concentration, when split into depression (MDD) and obsessive-compulsive disorder (OCD) diagnoses, the probability of clinical improvement significantly increased as both dose and concentration increased for OCD, but not for MDD.

CONCLUSIONS

This TDM-flexible-dose study revealed a significant diagnosis-specific effect between sertraline serum concentration and clinical efficacy for pediatric OCD. While TDM already guides clinical decision-making regarding compliance, dose calibration, and drug-drug interactions, combining TDM with other methods, such as pharmacogenetics, may facilitate a personalized medicine approach in psychiatry.

All-Solid-State Potentiometric Platforms Modified with a Multi-Walled Carbon Nanotubes for Fluoxetine Determination

Novel cost-effective screen-printed potentiometric platforms for simple, fast, and accurate assessment of Fluoxetine (FLX) were designed and characterized. The potentiometric platforms integrate both the FLX sensor and the reference Ag/AgCl electrode. The sensors were based on the use of 4′-nitrobenzo-15-crown-5 (ionophore I), dibenzo-18-crown-6 (ionophore II), and 2-hydroxypropyl-β-cyclodextrin (2-HP-β-CD) (ionophore III) as neutral carriers within a plasticized PVC matrix. Multiwalled carbon nanotubes (MWCNTs) were used as a lipophilic ion-to-electron transducing material and sodium tetrakis [3,5-bis(trifluoromethyl)phenyl] borate (NaTFPB) was used as an anionic excluder. The presented platforms revealed near-Nernstian potentiometric response with slopes of 56.2 ± 0.8, 56.3 ± 1.7 and 64.4 ± 0.2 mV/decade and detection limits of 5.2 × 10−6, 4.7 × 10−6 and 2.0 × 10−7 M in 10 mM Tris buffer solution, pH 7 for sensors based on ionophore I, II, and III, respectively. All measurements were carried out in 10 mM tris buffer solution at pH 7.0. The interfacial capacitance before and after insertion of the MWCNTs layer was evaluated for the presented sensors using the reverse-current chronopotentiometry. The sensors were introduced for successful determination of FLX drug in different pharmaceutical dosage forms. The results were compared with those obtained by the standard HPLC method. Recovery values were calculated after spiking fixed concentrations of FLX in different serum samples. The presented platforms can be potentially manufacturable at large scales and provide a portable, rapid, disposable, and cost-effective analytical tool for measuring FLX.

Protocol for a Pragmatic Trial of Pharmacotherapy Options Following Unsatisfactory Initial Treatment in OCD (PROCEED)

BACKGROUND

Selective serotonin reuptake inhibitors (SSRIs) are the first-line pharmacotherapy for obsessive-compulsive disorder (OCD), but a large proportion of patients do not achieve remission after an adequate SSRI trial. To the best of our knowledge, there have been no well-powered randomized controlled trials (RCTs) of sequenced pharmacotherapy using pragmatic research designs. China provides a unique context for undertaking such a trial that will recruit the largest treatment-naïve participants and systematically compare the efficacy of different sequenced pharmacotherapy.

METHODS

A pragmatic research design will be adopted, with n = 1,600 treatment-naïve OCD patients initially treated for sertraline for 12 weeks, and with non-remitters then randomized to 5 different augmentation or switching pharmacotherapy options for another 12 weeks. The 5 arms will include: (1) treatment with higher than usual doses of sertraline, (2) switch to fluvoxamine, (3) switch to venlafaxine, (4) augmentation with memantine, and (5) augmentation with aripiprazole.

DISCUSSION

China is uniquely positioned to recruit sufficiently large sample sizes of treatment-naïve OCD patients to compare different pharmacotherapy options; data from the proposed trial promises to help inform current clinical practice guidelines by providing important information about optimal pharmacotherapy choice for those who demonstrate no response or response but no remission to first line pharmacotherapy.

TRIAL REGISTRATION

The trail was registered on 27 August 2020 in ClinicalTrials.gov (https://register.clinicaltrials.gov/) (NCT04539951).

Development and validation of an automated solid-phase extraction-LC-MS/MS method for the bioanalysis of fluoxetine in human plasma

A wide-range, specific, and precise liquid chromatography tandem mass spectrometric (LC-MS/MS)technique for quantifying fluoxetine (FLX) in human plasma was developed using the RapidTrace^® automated solid-phase extraction (SPE) method; the analyte and internal standard (IS) were extricated on Oasis MCX SPE cartridges. Acetonitrile and 5 mM ammonium formate buffer (90:10 v/v) were used as mobile phase to achieve chromatographic separation on the reverse phase (C₁₈ column). The analyte and IS were ionized using +ve electrospray ionization approach which was further traced by multiple-reaction monitoring on a tandem mass spectrometer. To quantify the FLX and FLX-d5, the parent-to-daughter ion transition of m/z of 310.0/44.1 and 315.0/44.0 was used, respectively. The method demonstrated a linear active limit of 0.20-30 ng/ml with recoveries ranging from 63.04% to 79.39% for quality control samples and 61.25% for IS samples. The concentrations over the calibration range demonstrated acceptable precision and accuracy. Due to the high inconsistency of the FLX concentration data, the minimum threshold of the assay was kept at 0.20 ng/ml. The flow rate was maintained at 500 μL/min, and the time for sample analysis for each injection was 3.5 min. The method was found to be specific, sensitive, and faster with minimum utilization of organic solvents and was utilized further for metabolic and pharmacokinetic studies.

Functional characterization of N-octyl 4-methylamphetamine variants and related bivalent compounds at the dopamine and serotonin transporters using Ca2+ channels as sensors

The early characterization of ligands at the dopamine and serotonin transporters, DAT and SERT, respectively, is important for drug discovery, forensic sciences, and drug abuse research. 4-Methyl amphetamine (4-MA) is a good example of an abused drug whose overdose can be fatal. It is a potent substrate at DAT and SERT where its simplest secondary amine (N-methyl 4-MA) retains substrate activity at them. In contrast, N-n-butyl 4-MA is very weak, therefore it was categorized as inactive at these transporters. Here, N-octyl 4-MA and other related compounds were synthesized, and their activities were evaluated at DAT and SERT. To expedite this endeavor, cells expressing DAT or SERT were co-transfected with a voltage-gated Ca2+ channel and, the genetically-encoded Ca2+ sensor, GCaMP6s. Control compounds and the newly synthesized molecules were tested on these cells using an automated multi-well fluorescence plate reader; substrates and inhibitors were identified successfully at DAT and SERT. N-Octyl 4-MA and three bivalent compounds were inhibitors at these transporters. These findings were validated by measuring Ca2+-mobilization using quantitative fluorescence microscopy. The bivalent molecules were the most potent of the series and were further characterized in an uptake-inhibition assay. Compared to cocaine, they showed comparable potency inhibiting uptake at DAT and higher potency at SERT. These observations support a previous hypothesis that amphetamine-related (and, here, N-extended alkyl and) bivalent arylalkylamine molecules are active at monoamine transporters, showing potent activity as reuptake inhibitors, and implicate the involvement of a distant auxiliary binding feature to account for their actions at DAT and SERT.

Case Report: Effect of Electroconvulsive Therapy on Obsessive-Compulsive Disorder Comorbid With Body Dysmorphic Disorder

Obsessive-compulsive disorder (OCD) is a chronic psychiatric condition that is associated with considerable morbidity, and ~90% of individuals with OCD have another psychiatric comorbidity. Patients with comorbid OCD and body dysmorphic disorder (BDD) have limited insight and poor psychosocial function, respond poorly to drug treatment, and have an increased risk of suicide. Modified electroconvulsive therapy (ECT) has been attempted to improve symptoms of OCD when drug treatment does not have a satisfactory effect. This report describes a patient who had OCD comorbid with BDD that was successfully treated with modified ECT. Although the mechanism of its effect is unclear, modified ECT may be an alternative treatment for patients with comorbid OCD and BDD. Its efficacy and mechanism of action require further investigation in a large sample of patients with these comorbid disorders.