Metabolic drug interactions with newer antipsychotics: a comparative review

Alert prescribing of clozapine: a comparison of five drug-drug interaction sources

Introduction

Clozapine, an antipsychotic used in the treatment of schizophrenia, is known for its serious side effects. In order to promote patient safety, drug-drug interaction (DDI) databases can be consulted by clinicians. In this study, the degree of consensus between five sources on DDIs with clozapine is determined.

Methods

The summary of product characteristics of clozapine, Delphicare interaction database, Stockley's interaction checker, the Lexicomp interaction database, and the interaction database of Clinical Pharmacology are included. By comparing the original categories assigned to interactions with clozapine by the included DDI sources, a degree of consensus between sources is determined. Furthermore, based on the combined information, an evaluation on the severity of each potential interaction is made.

Results

One hundred eighty-three potential DDIs with clozapine are retrieved from the five included sources. A consensus between sources is found in 47.5% (n = 87) of DDIs.

Conclusion

This study shows major discrepancies between five different sources on DDIs with clozapine. The potential impact of the use of one specific database on patient safety and prescribing behavior could prove to be problematic.

Therapeutic drug monitoring in children and adolescents with schizophrenia-spectrum, affective, behavioural, tic and other psychiatric disorders treated with aripiprazole: results of the TDM-VIGIL pharmacovigilance study

Aripiprazole is approved for various severe mental disorders in adults and adolescents. However, off-label prescribing is common, especially in children and adolescents (youth) in whom aripiprazole therapeutic serum level reference ranges are lacking for any disorders. The aim of the study was to evaluate the relationship between aripiprazole dose and serum concentrations and provide further knowledge on the use of aripiprazole in order to improve drug safety and effectiveness in the treatment of minors. The clinical course of youth treated with aripiprazole in the multicentre pharmacovigilance study TDM-VIGIL was systematically followed and serum concentrations measured. Sex, age, weight and comedications were analysed to identify possible effect modifiers. A preliminary therapeutic reference range was estimated for youth with schizophrenia-spectrum disorders, affective disorders and behavioural/emotional/tic disorders coded as treatment responders based on a Clinical-Global Impressions-Improvement (CGI-I) score of much or very much improved. In 93 youth (mean age = 15.2 ± 2.6, range = 7.4-18.2 years, females = 53%, CGI-Severity = 4.4 ± 1.1, responders = 64%), a positive, moderate correlation between the weight-normalized daily dose (WNDD) and aripiprazole serum concentration (=0.791, p < 0.0001) was found. The WNDD and co-medications that interact with CYP2D6 and CYP3A4 affected aripiprazole serum levels, explaining 64% of the variance. In patients within the preliminary therapeutic ranges determined by interquartile ranges (IQRs), slightly better outcomes and fewer adverse drug reactions were found versus patients within preliminary therapeutic ranges determined by the mean ± SD. The preliminary reference range for paediatric patients with schizophrenia-spectrum disorders calculated by the IQR showed an identical lower threshold (100-230 ng/ml) compared to adult schizophrenia-spectrum disorders patients (100-350 ng/ml). The preliminary therapeutic ranges for patients with affective disorders was: 60-160 ng/ml and for patients with behavioural/tic disorders 60-140 ng/ml. The therapeutic reference ranges for aripiprazole in youth estimated via the 25th and 75th IQRs may result in more clinically relevant therapeutic windows. Further studies need to confirm these results, especially in patients with affective and behavioural/tic disorder diagnoses.

Clozapine-associated adverse drug reactions in 38,349 psychiatric inpatients: drug surveillance data from the AMSP project between 1993 and 2016

Clozapine is a second-generation antipsychotic drug that offers superior treatment results in patients with schizophrenia but is also associated with significant risks. This study analyzes data on pharmacotherapy with clozapine and the associated adverse drug reactions (ADRs) in an inpatient setting including 38,349 patients. Data about the use of clozapine and reports of severe ADRs within the period 1993-2016 were obtained from the multicentered observational pharmacovigilance program "Arzneimittelsicherheit in der Psychiatrie" (AMSP). In total, 586 severe clozapine-associated ADRs were documented (1.53% of all patients exposed). Patients aged ≥65 years had a higher risk of ADRs than patients aged <65 years (1.96 vs. 1.48%; p = 0.021). Significantly more ADRs were attributed to clozapine alone (396; 67.6% of all 586 ADRs) than to a combination with other drugs. The most frequent ADRs were grand mal seizures (0.183% of all 38,349 patients exposed), delirium (0.180%), increased liver enzymes (0.120%), and agranulocytosis (0.107%). We detected 24 cases (0.063%) of clozapine-induced extrapyramidal symptoms, of which 8 (0.021%) were attributed to clozapine alone. Five ADRs resulted in death (0.013%): 2 due to agranulocytosis (41 cases total) (mortality = 4.88%) and 3 due to paralytic (sub)ileus (16 cases) (mortality = 18.75%). The median dose of clozapine in all patients treated was 300 mg/day, in patients who developed ADRs 250 mg/day. The main risk factor for an ADR was pre-existing damage of the affected organ system. Overall, the results of this study highlight the importance of alertness-especially of frequently overlooked symptoms-and appropriate monitoring during treatment with clozapine, even at low doses.

Haloperidol for Pain Management: A Narrative Review

The use of haloperidol in pain management has been a topic of interest for several decades. Haloperidol is a widely used antipsychotic medication with unique pharmacologic properties that make it a potential candidate for pain management. However, the efficacy and safety of haloperidol for pain management remain controversial. This narrative review provides a summary of the current literature on the use of haloperidol for pain management, including its pharmacology, clinical effectiveness, adverse effects, and dosing regimens. We performed a comprehensive search of the literature for this review. The most robust clinical data from the past decade suggest that haloperidol has good efficacy in the treatment of pain related to gastroparesis and migraines and has shown promise for opioid use reduction in patients with chronic pain or receiving palliative care. The overall side effect profile is excellent, with zero reported events of QT-related cardiac arrest and minimal reports of sedation and transient extrapyramidal effects such as akathisia. Dosing regimens used were heterogeneous, with most ranging from 1 to 5 mg per dose via intravenous, intramuscular, or oral route. Studies with designs that isolated the effects of haloperidol from combinations of other drugs were extremely limited. Further high-quality prospective studies are needed to determine the ideal role of haloperidol in the routine clinical management of painful conditions.

Optimizing antidepressant and clozapine co-prescription in clinical practice: A systematic review and expert recommendations

OBJECTIVES

To synthesize the information relevant for clinical practice on clozapine-antidepressant co-prescription concerning pharmacokinetic drug-drug interactions (DDI), adverse drug reactions (ADRs) associated with the co-prescription, antidepressant add-on for clozapine-resistant symptoms and antidepressant add-on for clozapine-induced ADRs.

METHODS

Articles were identified with MEDLINE, Web of Sciences and PsycINFO search from inception through April 2023. Data were synthesized narratively.

RESULTS

ADRs are most often induced by the co-prescription of antidepressants that inhibit CYP enzymes (fluvoxamine, fluoxetine, paroxetine). Fluvoxamine add-on is hazardous because of its potent inhibition of clozapine metabolism and has few indications (lowering daily number of clozapine tablets, reducing norclozapine-induced metabolic disturbances and other dose-dependent clozapine-induced ADRs). ADR frequency may be reduced by therapeutic drug monitoring and knowledge of other factors impacting clozapine metabolism (pneumonia, inflammation, smoking, etc.). Improvement of negative symptoms is the most documented beneficial effect of antidepressant add-on for clozapine-resistant psychotic symptoms. The add-on antidepressant should be chosen according to its safety profile regarding DDI with clozapine: antidepressants inhibiting clozapine metabolism or increasing the anticholinergic load should be avoided. Other indications of antidepressant add-on (affective or obsessive compulsive symptoms, sialorrhea, and enuresis) are poorly documented.

CONCLUSION

Antidepressant add-on to clozapine is associated with potential benefits in clozapine users as this strategy may contribute to reduce the burden of clozapine-resistant symptoms or of clozapine-induced ADRs. Further studies are needed to determine whether antidepressant add-on can reduce the risk of clozapine discontinuation.

A Chinese medicine called Danggui Longhui may be a new clinically relevant clozapine inducer: Two case reports identified by therapeutic drug monitoring

BACKGROUND

Danggui Longhui is a traditional Chinese medicine made from the dried root of Angelica sinensis. It is used in psychiatric patients in China to reduce associated constipation. In a population pharmacokinetic model in olanzapine patients from Beijing Anding Hospital, we demonstrate that dangguilonghui tablets doubled olanzapine clearance, indicating the induction of olanzapine metabolism. Olanzapine metabolism is similar to clozapine metabolism.

METHODS

Two cases of possible clozapine induction using dangguilonghui tablets 4 g/day were identified in Beijing Anding Hospital. Dividing the minimum therapeutic concentration of 350 ng/mL by the concentration-to-dose (C/D) ratio provides the minimum therapeutic dose.

RESULTS

Case 1 was a female smoker on clozapine for 415 days. The mean of 6 clozapine C/D ratios associated with smoking provided a minimum therapeutic dose of 267 mg/day. There were 6 steady-state concentrations on the combination of valproic acid and dangguilonghui tablets, which provided a much higher minimum therapeutic dose of 833 mg/day. Four steady-state clozapine C/D ratios based on smoking and valproate after 4 months of carbamazepine 200 mg/day provided a minimum therapeutic dose of 603 mg/day. Case 2 was a female non-smoker on clozapine for 58 days. She had 3 clozapine C/D ratios on dangguilonghui tablets with a mean of 0.30 ng/mL providing a minimum therapeutic dose of 1167 mg/day.

CONCLUSION

Future clinical studies with repeated measures need to replicate the possibility that dangguilonghui tablets are a moderate-to-strong inducer of clozapine metabolism as suggested by these two limited cases.

Therapeutic Drug Monitoring in Psychiatry: Enhancing Treatment Precision and Patient Outcomes

Psychiatric disorders often require pharmacological interventions to alleviate symptoms and improve quality of life. However, achieving an optimal therapeutic outcome is challenging due to several factors, including variability in the individual response, inter-individual differences in drug metabolism, and drug interactions in polytherapy. Therapeutic drug monitoring (TDM), by measuring drug concentrations in biological samples, represents a valuable tool to address these challenges, by tailoring medication regimens to each individual. This review analyzes the current landscape of TDM in psychiatric practice, highlighting its significance in optimizing drug dosages, minimizing adverse effects, and improving therapeutic efficacy. The metabolism of psychiatric medications (i.e., mood stabilizers, antipsychotics, antidepressants) often exhibits significant inter-patient variability. TDM can help address this variability by enhancing treatment personalization, facilitating early suboptimal- or toxic-level detection, and allowing for timely interventions to prevent treatment failure or adverse effects. Furthermore, this review briefly discusses technological advancements and analytical methods supporting the implementation of TDM in psychiatric settings. These innovations enable quick and cost-effective drug concentration measurements, fostering the widespread adoption of TDM as a routine practice in psychiatric care. In conclusion, the integration of TDM in psychiatry can improve treatment outcomes by individualizing medication regimens within the so-called precision medicine.

Evidence for Therapeutic Drug Monitoring of Atypical Antipsychotics

Second-generation antipsychotics (SGAs), also known as atypical antipsychotics, are a newer class of antipsychotic drugs used to treat schizophrenia, bipolar disorder, and related psychiatric conditions. The plasma concentration of antipsychotic drugs is a valid measure of the drug at its primary target structure in the brain, and therefore determines the efficacy and safety of these drugs. However, despite the well-known high variability in pharmacokinetics of these substances, psychiatric medication is usually administered in uniform dosage schedules. Therapeutic drug monitoring (TDM), as the specific method that can help personalised medicine in dose adjustment according to the characteristics of the individual patient, minimizing the risk of toxicity, monitoring adherence, and increasing cost-effectiveness in the treatment, thus seems to be an elegant tool to solve this problem. Non-response to therapeutic doses, uncertain adherence to medication, suboptimal tolerability, or pharmacokinetic drug-drug interactions are typical indications for TDM of SGAs. This review aims to summarize an overview of the current knowledge and evidence of the possibilities to tailor the dosage of selected SGAs using TDM, including the necessary pharmacokinetic parameters for personalised pharmacotherapy.

[Therapeutic drug monitoring of clozapine]

Clozapine is a prototypical atypical antipsychotic used to treat severe schizophrenia and for which a therapeutic drug monitoring (TDM) is quite commonly proposed. Clozapine is rapidly absorbed (maximum concentration reached within 1 to 4hours), and is extensively metabolized in the liver by CYP1A2 to an active metabolite (and to a lesser extent, to inactive metabolites via other enzymes). Its half-life is 8 to 16h. A therapeutic range has been proposed for clozapine as some studies have reported both a relationship between low plasmatic concentrations and resistance to treatment (threshold level is likely between 250 and 400μg/L), and a relationship between high plasmatic concentrations and an increase in the occurrence of toxicity (alert level=1000μg/L). Given the data obtained in different studies, the TDM was evaluated for this molecule, to recommended.

Case report: application of pharmacogenetics in the personalized treatment of an elderly patient with a major depressive episode

Background

Pharmacogenetic analyses can predict interpersonal differences in response to psychopharmacotherapy, which greatly facilitates the selection of the most effective medication at optimal doses. By personalizing therapy in this way, we can minimize adverse drug reactions (ADR) and prevent polypharmacy. Most psychotropic medications are metabolized by the cytochrome P450 enzymes CYP2D6, CYP2C19, and CYPA3A4, which influence drug metabolism and concentration, affecting both efficacy and the occurrence of ADR. The relationships between genetic variations and enzymatic activity allow pharmacogenetic analysis to provide important data for optimal drug selection. The following case report illustrates the impact of pharmacogenetic analysis on the course of pharmacologic treatment in an elderly patient with a major depressive episode.

Methods

We present a case of a 79-year-old patient treated for severe depression with psychotic symptoms. We collected data on treatment selection and response to treatment before and after pharmacogenetic analysis. For pharmacogenetic analysis, common functional variants in CYP1A2, CYP3A4, CYP2B6, CYP2C19, and CYP2D6 were genotyped, and corresponding evidence-based treatment recommendations were prepared.

Results

The patient suffered from lack of efficacy and serious ADR of several medications, resulting in worsening depression and treatment resistance over the course of several months of treatment. Pharmacogenetic analysis provided important insights into the patient's pharmacokinetic phenotype and allowed us to personalize treatment and achieve remission of the depressive episode.

Conclusion

In the case presented, we have shown how consideration of pharmacogenetic characteristics in an individual patient can improve treatment outcome and patient well-being. Knowledge of the patient's pharmacogenetic characteristics helped us to personalize treatment, resulting in complete remission of psychopathology. Due to the complexity of psychiatric disorders, the efficacy of combinations of different medications, which are often required in individual patients, cannot be clearly explained. Therefore, it is of great importance to conduct further pharmacokinetic and pharmacogenetic studies to better assess gene-drug interactions in psychopharmacotherapy.

Predicting plasma concentration of quetiapine in patients with depression using machine learning techniques based on real-world evidence

OBJECTIVES

We develop a model for predicting quetiapine levels in patients with depression, using machine learning to support decisions on clinical regimens.

METHODS

Inpatients diagnosed with depression at the First Hospital of Hebei Medical University from 1 November 2019, to 31 August were enrolled. The ratio of training cohort to testing cohort was fixed at 80%:20% for the whole dataset. Univariate analysis was executed on all information to screen the important variables influencing quetiapine TDM. The prediction abilities of nine machine learning and deep learning algorithms were compared. The prediction model was created using an algorithm with better model performance, and the model's interpretation was done using the SHapley Additive exPlanation.

RESULTS

There were 333 individuals and 412 cases of quetiapine TDM included in the study. Six significant variables were selected to establish the individualized medication model. A quetiapine concentration prediction model was created through CatBoost. In the testing cohort, the projected TDM's accuracy was 61.45%. The prediction accuracy of quetiapine concentration within the effective range (200-750 ng/mL) was 75.47%.

CONCLUSIONS

This study predicts the plasma concentration of quetiapine in depression patients by machine learning, which is meaningful for the clinical medication guidance.

Evaluation of various scoring systems as predictors of the need for intensive care unit admission and other adverse outcomes among patients with acute clozapine poisoning

Acute clozapine poisoning (ACP) is frequently reported worldwide. We evaluated the efficacy of the Poison Severity Score (PSS), Acute Physiology and Chronic Health Evaluation II (APACHE II) score, Rapid Emergency Medicine Score (REMS), and Modified Early Warning Score (MEWS) as predictors for intensive care unit (ICU) admission, mechanical ventilation (MV), mortality, and length of hospital stay in patients with ACP. A retrospective cohort study was conducted using records of patients diagnosed with ACP from January 2017 to June 2022 and admitted to an Egyptian poison control center. Analyzing 156 records showed that all assessed scores were significant predictors of the studied outcomes. The PSS and APACHE II score showed the highest area under the curve (AUC) as ICU admission predictors with insignificant variations. The APACHE II score showed the best discriminatory power in predicting MV and mortality. Nevertheless, MEWS exhibited the highest odds ratio (OR) as an ICU predictor (OR = 2.39, and 95% confidence interval = 1.86-3.27) and as a mortality predictor (OR = 1.98, and 95% confidence interval = 1.16-4.41). REMS and MEWS were better predictors of length of hospital stay compared with the APACHE II score. The simpler, lab-independent nature and the comparable discrimination but higher odds ratio of MEWS compared with APACHE II score justify MEWS' superior utility as an outcome predictor in ACP. We recommend using either the APACHE II score or MEWS, depending on the availability of laboratory investigations, resources, and the case's urgency. Otherwise, the MEWS is a substantially feasible, economical, and bedside alternative outcome predictor in ACP.

Association Between Clozapine Plasma Concentrations and Treatment Response: A Systematic Review, Meta-analysis and Individual Participant Data Meta-analysis

BACKGROUND AND OBJECTIVES

Although therapeutic drug monitoring of clozapine is recommended, its optimisation is often adjusted only on the basis of dosage. The aim of this study was to assess the link between clozapine plasma concentrations and clinical response by a meta-analysis of published studies and by an individual participant data meta-analysis.

METHODS

We conducted a computerised search of bibliographic databases (EMBASE, PubMed, Clinical Trials, and Web of Science) to identify studies that assessed the relationship between clozapine serum or plasma concentrations and clinical efficacy. Using pooled data, we investigated the association between improvement of clinical outcome and clozapine or norclozapine plasma concentrations, the sum of clozapine and norclozapine plasma concentrations, and the coefficient of variation of clozapine plasma concentrations. Using available individual data, we assessed the relationship between clozapine plasma concentrations and clinical response (changes in the Brief Psychiatric Rating Scale score) and identified a threshold level for a favourable clinical response.

RESULTS

Fifteen studies satisfied inclusion criteria. Our meta-analysis showed that responders had clozapine plasma concentrations that were, on average, 117 ng/mL higher than non-responders. The patients with plasma clozapine concentrations above the thresholds identified in each study had a higher likelihood of responding (odds ratio = 2.94, p < 0.001). Norclozapine plasma concentrations were not associated with a clinical response. The meta-analysis of individual data supported this result and confirmed the link between clozapine concentrations and a change in the Brief Psychiatric Rating Scale score and/or the probability of clinical response. Finally, with the analysis of the coefficient of variation of clozapine plasma concentrations, we found that a greater inter-individual fluctuation in plasma concentrations was associated with a loss of clinical response.

CONCLUSIONS

Our work confirmed that, in contrast to clozapine doses, clozapine plasma concentrations were related to a favourable clinical response, with a mean difference between responders and non-responders of 117 ng/mL. A threshold for a treatment response of 407 ng/mL was determined, with a high discriminatory capacity, and a sensitivity and specificity of 71% and 89.1%, respectively.

Seventy Years of Antipsychotic Development: A Critical Review

Since the mid-1950s discovery of the first effective antipsychotic medications (APM), we have only been able to improve the tolerability but not the overall efficacy of currently available APMs, as reflected by effectiveness trials in Europe and the United States. This inability to develop more effective APMs is attributable to multiple factors, including failure to create and use assessment tools to assess core symptom domains in schizophrenia, move beyond the dopaminergic hypothesis and to develop "me too" drugs, imposing ill-defined research domain criteria, and lacking federal funding for clinical trials. The classification of APMs is also confusing, including second-generation, partial agonists, and multimodal APMs in the same class of APMs, despite significant differences in their mechanisms of action. Other factors stagnating drug development include inadequate sample sizes to address heterogeneity, lack of statistical measures correlating with clinical significance, using the atheoretical basis of psychiatric diagnoses, failure to control placebo response, and high cost of newer and perhaps more tolerable APMs. Furthermore, there has been a failure to develop early predictors of antipsychotic response and various tools to optimize an APM response. Finally, some mental health providers are also responsible for the suboptimal use of APMs, by using excessive maintenance doses, often with irrational polypharmacy, further compromising effectiveness and medication adherence. However, some bright spots in antipsychotic development include improved tolerability of APMs and long-acting injectables to address the high prevalence of medication nonadherence. This review critically reviews 70 years of antipsychotic development, the reasons behind the failure to develop more effective APMs, and suggestions for future direction.

The Effect of Menopause on Antipsychotic Response

Background: It has been hypothesized that, whenever estrogen levels decline, psychosis symptoms in women increase. At menopause, this can happen in two main ways: (a) the loss of estrogen (mainly estradiol) can directly affect central neurotransmission, leading to increase in schizophrenia-related symptoms, and (b) the loss of estrogen can decrease the synthesis of enzymes that metabolize antipsychotic drugs, thus weakening their efficacy. Aims and Methods: The aim of this narrative review was to investigate the second possibility by searching PubMed and ClinicalTrials.gov for studies over the last two decades that investigated the metabolism of antipsychotics and their efficacy before and after menopause in women or that studied systemic and local estrogen level effects on the pharmacokinetics and pharmacodynamics of individual antipsychotic drugs. Results: The evidence suggests that symptom level in women with schizophrenia rises after menopause for many reasons beyond hormones but, importantly, there is an estrogen-dependent loss of efficacy related to antipsychotic treatment. Conclusion: Effective clinical intervention is challenging; nevertheless, several promising routes forward are suggested.

CYP2D6 Genetic Variation and Antipsychotic-Induced Weight Gain: A Systematic Review and Meta-Analysis

BACKGROUND

Antipsychotic-induced weight gain is a contributing factor in the reduced life expectancy reported amongst people with psychotic disorders. CYP2D6 is a liver enzyme involved in the metabolism of many commonly used antipsychotic medications. We investigated if CYP2D6 genetic variation influenced weight or BMI among people taking antipsychotic treatment.

METHODS

We conducted a systematic review and a random effects meta-analysis of publications in Pubmed, Embase, PsychInfo, and CENTRAAL that had BMI and/or weight measurements of patients on long-term antipsychotics by their CYP2D6-defined metabolic groups (poor, intermediate, normal/extensive, and ultra-rapid metabolizers, UMs).

RESULTS

Twelve studies were included in the systematic review. All cohort studies suggested that the presence of reduced-function or non-functional alleles for CYP2D6 was associated with greater antipsychotic-induced weight gain, whereas most cross-sectional studies did not find any significant associations. Seventeen studies were included in the meta-analysis with clinical data of 2,041 patients, including 93 poor metabolizers (PMs), 633 intermediate metabolizers (IMs), 1,272 normal metabolizers (NMs), and 30 UMs. Overall, we did not find associations in any of the comparisons made. The estimated pooled standardized differences for the following comparisons were (i) PM versus NM; weight = -0.07 (95%CI: -0.49 to 0.35, p = 0.74), BMI = 0.40 (95%CI: -0.19 to 0.99, p = 0.19). (ii) IM versus NM; weight = 0.09 (95% CI: -0.04 to 0.22, p = 0.16) and BMI = 0.09 (95% CI: -0.24 to 0.41, p = 0.60). (iii) UM versus EM; weight = 0.01 (95% CI: -0.37 to 0.40, p = 0.94) and BMI = -0.08 (95%CI: -0.57 to 0.42, p = 0.77).

CONCLUSION

Our systematic review of cohort studies suggested that CYP2D6 poor metabolizers have higher BMI than normal metabolizers, but the data of cross-sectional studies and the meta-analysis did not show this association. Although our review and meta-analysis constitutes one of the largest studies with comprehensively genotyped samples, the literature is still limited by small numbers of participants with genetic variants resulting in poor or UMs status. We need further studies with larger numbers of extreme metabolizers to establish its clinical utility in antipsychotic treatment. CYP2D6 is a key gene for personalized prescribing in mental health.

Monte Carlo optimization method based QSAR modeling of postmortem redistribution of structurally diverse drugs

The Monte Carlo optimization method was employed for the development of the QSAR model for the prediction for postmortem redistribution of structurally diverse drugs.

Selective Serotonin Reuptake Inhibitors and Clozapine: Clinically Relevant Interactions and Considerations

The monoamine hypothesis of depression attributes the symptoms of major depressive disorders to imbalances of serotonin, noradrenaline, and dopamine in the limbic areas of the brain. The preferential targeting of serotonin receptor (SERT) by selective serotonin reuptake inhibitors (SSRIs) has offered an opportunity to reduce the range of these side effects and improve patient adherence to pharmacotherapy. Clozapine remains an effective drug against treatment-resistant schizophrenia, defined as failing treatment with at least two different antipsychotic medications. Patients with schizophrenia who display a constellation of negative symptoms respond poorly to antipsychotic monotherapy. Negative symptoms include the diminution of motivation, interest, or expression. Conversely to the depressive symptomology of interest presently, supplementation of antipsychotics with SSRIs in schizophrenic patients with negative symptoms lead to synergistic improvements in the function of these patients. Fluvoxamine is one of the most potent inhibitors of CYP1A2 and can lead to an increase in clozapine levels. Similar increases in serum clozapine were detected in two patients taking sertraline. However, studies have been contradictory as well, showing no such increases, which are worrying. Clinicians should be aware that clozapine levels should be monitored with any coadministration with SSRIs.

The Influence of Long-Term Treatment with Asenapine on Liver Cytochrome P450 Expression and Activity in the Rat. The Involvement of Different Mechanisms

Therapy of schizophrenia requires long-term treatment with a relevant antipsychotic drug to achieve a therapeutic effect. The aim of the present study was to investigate the influence of prolonged treatment with the atypical neuroleptic asenapine on the expression and activity of rat cytochrome P450 (CYP) in the liver. The experiment was carried out on male Wistar rats. Asenapine (0.3 mg/kg s.c.) was administered for two weeks. The levels of CYP mRNA protein and activity were determined in the liver and hormone concentrations were measured in the pituitary gland and blood serum. Asenapine significantly decreased the activity of CYP1A (caffeine 8-hydroxylation and 3-N-demethylation), CYP2B, CYP2C11 and CYP3A (testosterone hydroxylation at positions 16β; 2α and 16α; 2β and 6β, respectively). The neuroleptic did not affect the activity of CYP2A (testosterone 7α-hydroxylation), CYP2C6 (warfarin 7-hydroxylation) and CYP2E1 (chlorzoxazone 6-hydroxylation). The mRNA and protein levels of CYP1A2, CYP2B1, CYP2C11 and CYP3A1 were decreased, while those of CYP2B2 and CYP3A2 were not changed. Simultaneously, pituitary level of growth hormone-releasing hormone and serum concentrations of growth hormone and corticosterone were reduced, while that of triiodothyronine was enhanced. In conclusion, chronic treatment with asenapine down-regulates liver cytochrome P450 enzymes, which involves neuroendocrine mechanisms. Thus, chronic asenapine treatment may slow the metabolism of CYP1A, CYP2B, CYP2C11 and CYP3A substrates (steroids and drugs). Since asenapine is metabolized by CYP1A and CYP3A, the neuroleptic may inhibit its own metabolism, therefore, the plasma concentration of asenapine in patients after prolonged treatment may be higher than expected based on a single dose.

Bioequivalence of 2 Aripiprazole Orally Disintegrating Tablets in Healthy Chinese Volunteers Under Fasting and Fed Conditions

To assess the bioequivalence of 2 formulations of aripiprazole orally disintegrating tablets and to monitor their safety and tolerability in Chinese subjects, a single-site, open-label, randomized, 2-preparation, single-dose, 2-period crossover design was conducted. All 60 subjects were randomly divided into the fasting group and the fed group. Blood samples were collected at scheduled times after a single oral dose of orodispersible tablets containing 10 mg of aripiprazole. In the fasting state, the geometric mean ratios (90% confidence intervals [CIs]) of the test/reference formulation were 92.22%-100.20% for the area under the concentration-time curve (AUC) from time zero to the last measured concentration (AUC_0-t ), 91.73%-100.14% for the AUC from administration to infinite time (AUC_0-∞ ), and 98.52%-112.52% for the maximum plasma concentration (C_max ). In the fed state, AUC_0-t , AUC_0-∞ , and C_max were 92.23%-100.20%, 91.73%-100.14%, and 95.91%-105.13%, respectively. The 90%CIs of the test/reference AUC ratio and C_max ratio were within the acceptance range of 80.00%-125.00% for bioequivalence. Neither the maximum peak plasma concentration (t_max ) nor the terminal elimination half-life (t_1/2 ) showed any significant difference. No serious adverse events) were encountered during the study. The test and reference formulations were bioequivalent under both fasting and fed conditions and were found to be safe and tolerated.

Risk of Prolonged Corrected QT Interval With Amisulpride Therapy for Renal Function Management in Patients With Schizophrenia

BACKGROUND

Amisulpride (AMI) is a popular antipsychotic drug prescribed for the management of schizophrenia. However, patients may experience prolonged corrected QT (QTc) interval. We therefore aimed to assess the risk factors for QTc prolongation during AMI therapy in patients with schizophrenia.

METHODS

This study retrospectively enrolled 271 patients with schizophrenia. Continuous variables were analyzed with a t test or analysis of variance, and categorical variables were analyzed with a χ test. Patients with and without QTc prolongation were compared using a backward stepwise logistic regression analysis to identify the important variables.

RESULTS

Comedication of AMI with clozapine (odds ratio, 3.5 [95% confidence interval, 1.3-9.7]) and decreased renal function (mildly decrease, 3.4 [1.2-10.1]; mild to moderately decreased, 4.8 [1.3-17.3]; moderately decreased, 13.6 [2.0-90.6]) were identified as the independent risk factors of QTc prolongation. The dose-normalized plasma concentration of AMI (plasma concentration per dose) was significantly higher in the QTc prolongation group (z = -1.735, P = 0.015) and renal dysfunction group (F = 16.002, P < 0.001).

CONCLUSIONS

Renal function should be monitored in patients prescribed with AMI, particularly in those taking clozapine. Plasma concentration per dose values can be considered as a risk factor of QTc interval prolongation. The founding help clinicians to analyze the risk of QTc prolongation before prescribing AMI and to monitor QTc prolongation during AMI therapy.

Therapeutic Drug Monitoring of Olanzapine and Cytochrome P450 Genotyping in Nonsmoking Subjects

BACKGROUND

The relationship between a daily dose of olanzapine, its serum concentration, and the genotype of young nonsmoking men treated for schizophrenia or schizophreniform disorder was investigated in day-to-day clinical practice. Pharmacogenetics was also examined for the selected patients.

METHODS

A total of 49 participants were recruited as in-patients at the Mental Health Research Center (Moscow, Russia). Inclusion criteria were patients who had been diagnosed with schizophrenia or schizoaffective disorder (following DSM-IV guidelines) and were being treated with OLZ. A prospective, observational, open-study design was implemented. In line with the literature, patients were only included if they attained steady-state OLZ concentrations lasting for at least 8 days. A liquid chromatographic-tandem mass spectrometric method was developed for analyzing OLZ in human serum. The single cytochrome P450 polymorphisms were genotyped using an amplifier real-time polymerase chain reaction system following standard protocols.

RESULTS

Evidence indicating that CYP2D6 polymorphism has a significant (P = 0.046) effect on the pharmacokinetics of olanzapine was obtained, confirming the beneficial effects of therapeutic drug monitoring (TDM) for olanzapine.

CONCLUSIONS

TDM should therefore be used as a standard care during olanzapine therapy. TDM is also useful in assessing adherence and may have a role in limiting olanzapine dosage geared at minimizing the risk of long-term toxicity.

Edoxaban and the Issue of Drug-Drug Interactions: From Pharmacology to Clinical Practice

Edoxaban, a direct factor Xa inhibitor, is the latest of the non-vitamin K antagonist oral anticoagulants (NOACs). Despite being marketed later than other NOACs, its use is now spreading in current clinical practice, being indicated for both thromboprophylaxis in patients with non-valvular atrial fibrillation (NVAF) and for the treatment and prevention of venous thromboembolism (VTE). In patients with multiple conditions, the contemporary administration of several drugs can cause relevant drug-drug interactions (DDIs), which can affect drugs' pharmacokinetics and pharmacodynamics. Usually, all the NOACs are considered to have significantly fewer DDIs than vitamin K antagonists; notwithstanding, this is actually not true, all of them are affected by DDIs with drugs that can influence the activity (induction or inhibition) of P-glycoprotein (P-gp) and cytochrome P450 3A4, both responsible for the disposition and metabolism of NOACs to a different extent. In this review/expert opinion, we focused on an extensive report of edoxaban DDIs. All the relevant drugs categories have been examined to report on significant DDIs, discussing the impact on edoxaban pharmacokinetics and pharmacodynamics, and the evidence for dose adjustment. Our analysis found that, despite a restrained number of interactions, some strong inhibitors/inducers of P-gp and drug-metabolising enzymes can affect edoxaban concentration, just as it happens with other NOACs, implying the need for a dose adjustment. However, our analysis of edoxaban DDIs suggests that given the small propensity for interactions of this agent, its use represents an acceptable clinical decision. Still, DDIs can be significant in certain clinical situations and a careful evaluation is always needed when prescribing NOACs.

Chemical Aspects of Human and Environmental Overload with Fluorine

Over the last 100-120 years, due to the ever-increasing importance of fluorine-containing compounds in modern technology and daily life, the explosive development of the fluorochemical industry led to an enormous increase of emission of fluoride ions into the biosphere. This made it more and more important to understand the biological activities, metabolism, degradation, and possible environmental hazards of such substances. This comprehensive and critical review focuses on the effects of fluoride ions and organofluorine compounds (mainly pharmaceuticals and agrochemicals) on human health and the environment. To give a better overview, various connected topics are also discussed: reasons and trends of the advance of fluorine-containing pharmaceuticals and agrochemicals, metabolism of fluorinated drugs, withdrawn fluorinated drugs, natural sources of organic and inorganic fluorine compounds in the environment (including the biosphere), sources of fluoride intake, and finally biomarkers of fluoride exposure.

Atypical Antipsychotics and Metabolic Syndrome: From Molecular Mechanisms to Clinical Differences

Atypical antipsychotics (AAPs) are commonly prescribed medications to treat schizophrenia, bipolar disorders and other psychotic disorders. However, they might cause metabolic syndrome (MetS) in terms of weight gain, dyslipidemia, type 2 diabetes (T2D), and high blood pressure, which are responsible for reduced life expectancy and poor adherence. Importantly, there is clear evidence that early metabolic disturbances can precede weight gain, even if the latter still remains the hallmark of AAPs use. In fact, AAPs interfere profoundly with glucose and lipid homeostasis acting mostly on hypothalamus, liver, pancreatic β-cells, adipose tissue, and skeletal muscle. Their actions on hypothalamic centers via dopamine, serotonin, acetylcholine, and histamine receptors affect neuropeptides and 5'AMP-activated protein kinase (AMPK) activity, thus producing a supraphysiological sympathetic outflow augmenting levels of glucagon and hepatic glucose production. In addition, altered insulin secretion, dyslipidemia, fat deposition in the liver and adipose tissues, and insulin resistance become aggravating factors for MetS. In clinical practice, among AAPs, olanzapine and clozapine are associated with the highest risk of MetS, whereas quetiapine, risperidone, asenapine and amisulpride cause moderate alterations. The new AAPs such as ziprasidone, lurasidone and the partial agonist aripiprazole seem more tolerable on the metabolic profile. However, these aspects must be considered together with the differences among AAPs in terms of their efficacy, where clozapine still remains the most effective. Intriguingly, there seems to be a correlation between AAP's higher clinical efficacy and increase risk of metabolic alterations. Finally, a multidisciplinary approach combining psychoeducation and therapeutic drug monitoring (TDM) is proposed as a first-line strategy to avoid the MetS. In addition, pharmacological treatments are discussed as well.

Therapeutic drug monitoring and pharmacogenetics of antipsychotics and antidepressants in real life settings: A 5-year single centre experience

OBJECTIVES

Exposure and clinical response to CNS drugs are largely variable. AGNP guidelines suggest therapy individualisation with therapeutic drug monitoring of plasma concentrations and pharmacogenetic testing. We present the retrospective analysis of the last 5 years' data collected in real life settings as indirect evidence of the applications of the AGNP guidelines in the routine clinical management of psychiatric patients requiring pharmacologic treatments.

METHODS

Plasma concentrations were quantified using a liquid chromatography/tandem mass spectrometry method. Genomic DNA was isolated using an automatic DNA extraction system. All genotypes were determined by Real-Time PCR.

RESULTS

We collected a total of 4582 requests for TDM and 212 requests for pharmacogenetic analysis. A wide distribution in the trough concentrations was observed for most drugs indicating a high interpatient variability. Nearly 45% of the samples had trough levels below the minimum effective drug concentrations set by the AGNP guidelines; only 8% of the samples had high concentrations. For pharmacogenetics analysis, among antipsychotics, clozapine, haloperidol and aripiprazole were the most requested (78%); while for antidepressants SSRIs were the most frequently prescribed.

CONCLUSIONS

These data suggest that physicians are becoming more confident with the laboratory pharmacologic tools to optimise treatments and/or that the pharmacological treatment of patients with psychiatric disorders is becoming more challenging. TDM and PGx might significantly contribute to the rational selection of the best drug and best dose in individual cases.

The More, the Merrier…? Antipsychotic Polypharmacy Treatment Strategies in Schizophrenia From a Pharmacology Perspective

Antipsychotic polypharmacy/drug combination treatment (APP) is a remarkably common practice in the schizophrenia context, given the lack of general support in treatment Guidelines. There is also a vast literature on APP outcomes, but a paucity of high-quality evidence-based data to guide and optimize adequate use of APP. This seems particularly true regarding many pharmacology-based considerations involved in APP treatment strategies. This paper first briefly summarizes clinical literature related to the use of APP. Against this backdrop, the pharmacological target profile features are then described of frequently used antipsychotic agents, in relation to estimated free plasma exposure levels at clinically efficacious dosing. APP strategies based on the properties of these drugs are then scrutinized and gauged within the background literature framework. The anticipated usefulness of APP from the pharmacological standpoint is detailed regarding efficacy, adverse effect (AE)/tolerability, and safety perspective, including why, when, and how it may be used to its advantage. For the purpose, a number of theoretically beneficial combinations as well as instances with suboptimal-and even futile-APP approaches are exemplified and discussed from the rational pharmacodynamic and pharmacokinetic pros and cons point-of-view. In this exposé, particular attention is paid to the utility and features of 3rd Generation Antipsychotic dopamine (DA) D2-D3 agonists within an APP setting.

Pharmacogenetics of antipsychotics: Clinical utility and implementation

Decades of research have produced extensive evidence of the contribution of genetic factors to the efficacy and toxicity of antipsychotics. Numerous genetic variants in genes controlling drug availability or involved in antipsychotic processes have been linked to treatment variability. The complex mechanism of action and multitarget profile of most antipsychotic drugs hinder the identification of pharmacogenetic markers of clinical value. Nevertheless, the validity of associations between variants in CYP1A2, CYP2D6, CYP2C19, ABCB1, DRD2, DRD3, HTR2A, HTR2C, BDNF, COMT, MC4R genes and antipsychotic response has been confirmed in independent candidate gene studies. Genome wide pharmacogenomic studies have proven the role of the glutamatergic pathway in mediating antipsychotic activity and have reported novel associations with antipsychotic response. However, only a limited number of the findings, mainly functional variants of CYP metabolic enzymes, have been shown to be of clinical utility and translated into useful pharmacogenetic markers. Based on the currently available information, actionable pharmacogenetics should be reduced to antipsychotics' dose adjustment according to the genetically predicted metabolic status (CYPs' profile) of the patient. Growing evidence suggests that such interventions will reduce antipsychotics' side-effects and increase treatment safety. Despite this evidence, the use of pharmacogenetics in psychiatric wards is minimal. Hopefully, further evidence on the clinical and economic benefits, the development of clinical protocols based on pharmacogenetic information, and improved and cheaper genetic testing will increase the implementation of pharmacogenetic guided prescription in clinical settings.

Prescribed drugs containing nitrogen heterocycles: an overview

Heteroatoms as well as heterocyclic scaffolds are frequently present as the common cores in a plethora of active pharmaceuticals natural products. Statistically, more than 85% of all biologically active compounds are heterocycles or comprise a heterocycle and most frequently, nitrogen heterocycles as a backbone in their complex structures. These facts disclose and emphasize the vital role of heterocycles in modern drug design and drug discovery. In this review, we try to present a comprehensive overview of top prescribed drugs containing nitrogen heterocycles, describing their pharmacological properties, medical applications and their selected synthetic pathways. It is worth mentioning that the reported examples are actually limited to current top selling drugs, being or containing N-heterocycles and their synthetic information has been extracted from both scientific journals and the wider patent literature.

Clinically Relevant Interactions between Atypical Antipsychotics and Anti-Infective Agents

This is a comprehensive review of the literature on drug interactions (DIs) between atypical antipsychotics and anti-infective agents that focuses on those DIs with the potential to be clinically relevant and classifies them as pharmacokinetic (PK) or pharmacodynamic (PD) DIs. PubMed searches were conducted for each of the atypical antipsychotics and most commonly used anti-infective agents (13 atypical antipsychotics by 61 anti-infective agents/classes leading to 793 individual searches). Additional relevant articles were obtained from citations and from prior review articles written by the authors. Based on prior DI articles and our current understanding of PK and PD mechanism, we developed tables with practical recommendations for clinicians for: antibiotic DIs, antitubercular DIs, antifungal DIs, antiviral DIs, and other anti-infective DIs. Another table reflects that in clinical practice, DIs between atypical antipsychotics and anti-infective agents occur in patients also suffering an infection that may also influence the PK and PD mechanisms of both drugs (the atypical antipsychotic and the anti-infective agent(s)). These tables reflect the currently available literature and our current knowledge of the field and will need to be updated as new DI information becomes available.

Recent trends in antipsychotic polypharmacy in the treatment of schizophrenia

Ichihashi et al reported that 43% of patients had antipsychotic polypharmacy. Number of antipsychotics used in patients with schizophrenia in Japan was the greatest among Asian countries. However, the antipsychotic polypharmacy rate in Japan decreased gradually. Recent systematic review, meta‐analysis and meta‐regression analysis demonstrated that antipsychotic augmentation was superior to monotherapy. However, several cohort studies have suggested a significant association between antipsychotic daily dose and mortality. In addition, most pharmacokinetic interactions with antipsychotics occur at the metabolic level and usually involve changes in the activity of the major drug‐metabolizing enzymes involved in their biotransformation. Thus, avoidance of unnecessary polypharmacy, knowledge of the interaction profiles of individual agents, and careful individualization of dosage based on close evaluation of clinical response and possibly plasma drug concentrations are essential to prevent and minimize potentially adverse drug interactions in patients receiving antipsychotics.

A pilot study of the safety and efficacy of amisulpride and risperidone in elderly psychotic patients

Objective

The primary objective of this randomised, active–controlled, parallel group, double-blind study was to evaluate the tolerability of treatment with either amisulpride or risperidone in elderly patients with schizophrenia aged over 65 years; evaluation of efficacy was a secondary objective.

Methods

The study included patients of either sex aged 65 years or older fulfilling DSM IV-diagnostic criteria for psychotic disorders and who presented psychotic symptoms severe enough to require antipsychotic medication. Subjects were randomly allocated to a flexible dose of either amisulpride (100–400 mg/day) or risperidone (1–4 mg/day) for six weeks following a three- to six-day placebo wash-out period. Safety assessment involved adverse event reporting, physical examination, blood pressure, heart rate and ECG monitoring, and laboratory tests. Extrapyramidal symptoms were evaluated with the Simpson–Angus Scale, Barnes Akathisia Scale and the AIMS. Efficacy parameters were changes in score on the PANSS, BPRS, CDS and MMSE scores.

Results

Thirty-eight patients were randomised, 25 to amisulpride and 13 to risperidone. A total of 26 adverse events were experienced by 10 patients in the amisulpride group and five patients in the risperidone group. One patient in each group discontinued the study due to the emergence of a movement disorder. Changes in scores on the three measures of extrapyramidal symptoms were similar in the two groups. The PANSS total score decreased by 27.8% in the amisulpride group and by 29% in the risperidone group between inclusion and study end.

Conclusion

Amisulpride and risperidone are generally well tolerated in elderly patients with schizophrenia. Both drugs appeared to be efficacious in this study population, with no differences in efficacy being observed. However, the sample size was too low to reveal potential inter-group differences. Both these atypical antipsychotics thus appear to be suitable for the treatment of schizophrenia in the elderly.

A pharmacological profile of intravenous amisulpride for the treatment of postoperative nausea and vomiting

INTRODUCTION

The issue of postoperative nausea and vomiting (PONV) remains important in surgical practice, contributing to patient distress, slower recovery, and increased use of healthcare resources. Many surgical patients report it to be a worse problem than the pain. New antiemetics of different classes are still needed to help manage PONV effectively, especially the treatment of established PONV after the failure of common prophylactic antiemetics such as 5-HT₃-antagonists and corticosteroids. Intravenous amisulpride, a drug with a long history of safe use in oral form as an antipsychotic, has recently been approved in the US (trade name: Barhemsys) as an intravenous antiemetic for the prevention and treatment of PONV.

AREAS COVERED

This review article summarizes the published data on the clinical pharmacology, safety, and efficacy of intravenous amisulpride as an antiemetic, supplemented by published data on oral amisulpride, where relevant to the intravenous form. Literature was obtained via the PubMed search terms 'intravenous amisulpride' and 'amisulpride AND safety.' Both primary and secondary pharmacology are covered, along with clinical pharmacokinetics (distribution, metabolism, and excretion). The review of clinical safety and efficacy includes data from four studies in the prevention of PONV, two in the treatment of PONV and two investigating effects on the QT interval of the electrocardiogram in healthy volunteers.

EXPERT OPINION

Given the importance of sufficient PONV prevention for patients and the healthcare system, the availability of intravenous amisulpride is helpful, restoring the dopamine-antagonist class as a potential mainstay in both combination prophylaxis and treatment.

Dopamine Receptor Partial Agonists for the Treatment of Bipolar Disorder

Bipolar disorder is a chronic, disabling, and costly illness with frequent relapses and recurrences, high rates of co-morbid conditions, and poor adherence to treatment. Mood stabilizers and antipsychotics are the cornerstones of treatment. Dopamine receptor partial agonists are a novel class of antipsychotic agents with original pharmacodynamic properties. Among them, two have been approved by the US Food and Drug Administration for the treatment of bipolar disorder. Aripiprazole (oral formulation) has been approved as monotherapy for the treatment of manic/mixed episodes in adult and pediatric populations and for maintenance treatment in adults, and as adjunctive treatment to mood stabilizers, for the acute treatment of manic/mixed episodes and for maintenance in adults. An intramuscular formulation of aripiprazole has been approved for the treatment of agitation in mania and a long-acting injectable formulation has been approved as maintenance treatment. In the USA, cariprazine has been approved as monotherapy for the acute treatment of manic/mixed as well as bipolar depressive episodes. Brexpiprazole is not yet approved to treat bipolar disorder. The evidence supporting these indications is reviewed via an analysis of clinical registration trials as well as additional studies, on the basis of a systematic literature search. Further studies dealing with other aspects of bipolar illness are also presented. Aripiprazole and cariprazine are efficacious and generally well tolerated agents that have shown cost effectiveness, and may therefore enrich our therapeutic armamentarium for bipolar illness. Brexpiprazole, which displays an overall promising tolerability profile, deserves further efficacy studies.

Efficacy of amisulpride on postoperative nausea and vomiting: a systematic review and meta-analysis

AIM AND BACKGROUND

Postoperative nausea and vomiting (PONV) remains a significant clinical problem for surgical patients. Amisulpride is a well-studied D_2/D₃ antagonist that has the potential to be used for preventing and treating PONV. Our aim was to assess the efficacy and safety of amisulpride for prevention and treatment of PONV through a systematic review and meta-analysis.

METHOD

A systematic literature search was performed using MEDLINE, EMBASE, PUBMED, clinicaltrials.gov, and the Cochrane Central Register of Controlled Trials from their inception to Feb 15th, 2019. The efficacy outcome was the incidence of complete response, defined as no emesis and no rescue antiemetic use in a 24-h period after study drug administration. The safety outcomes were the adverse effects associated with amisulpride.

RESULTS

Five studies comprising 3243 patients met inclusion critieria. Compared with placebo, amisulpride showed a significantly improved incidence of complete response [relative risk (RR): 1.30; 95% confidence interval (CI): 1.20-1.41; P < 0.00001, I² = 0%] with firm evidence from the trial sequential analysis. Particularly, the amisulpride at 5 mg dose indicated a significant benefit than placebo [relative risk (RR): 1.28; 95% confidence interval (CI): 1.18-1.39; P < 0.00001, I² = 4%]. The adverse event profile of amisulpride was generally similar to the placebo.

CONCLUSION

Based on our findings, low-dose, intravenous amisulpride is safe and efficacious for the prevention and treatment of PONV compared to placebo. Further studies are needed to explore the optimal dose and timing.

CLINICAL TRIAL REGISTRATION

PROSPERO: CRD42019121483.

Physiologically-Based Pharmacokinetic Modeling for Predicting Drug Interactions of a Combination of Olanzapine and Samidorphan

A combination of the antipsychotic olanzapine and the opioid receptor antagonist samidorphan (OLZ/SAM) is intended to provide the antipsychotic efficacy of olanzapine while mitigating olanzapine-associated weight gain. As cytochrome P450 (CYP) 1A2 and CYP3A4 are the major enzymes involved in metabolism of olanzapine and samidorphan, respectively, physiologically-based pharmacokinetic (PBPK) modeling was applied to predict any drug-drug interaction (DDI) potential between olanzapine and samidorphan or between OLZ/SAM and CYP3A4/CYP1A2 inhibitors/inducers. A PBPK model for OLZ/SAM was developed and validated by comparing model-simulated data with observed clinical study data. Based on model-based simulations, no DDI between olanzapine and samidorphan is expected when administered as OLZ/SAM. CYP3A4 inhibition is predicted to have a weak effect on samidorphan exposure and negligible effect on olanzapine exposure. CYP3A4 induction is predicted to reduce both samidorphan and olanzapine exposure. CYP1A2 inhibition or induction is predicted to increase or decrease, respectively, olanzapine exposure only.

Metabolism and Excretion of Intravenous, Radio-Labeled Amisulpride in Healthy, Adult Volunteers

Purpose

Intravenous amisulpride, a dopamine D₂/D₃ antagonist, has recently been shown in trials to be an effective antiemetic at low doses. This study was conducted to investigate the metabolism and elimination of a single dose of intravenous ¹⁴C-labeled amisulpride in healthy, adult volunteers.

Patients and methods

Six healthy male volunteers aged 18–65 years were given a single 10 mg dose of ¹⁴C-labeled amisulpride containing not more than 1.8 MBq of radioactivity, infused over 4 mins. Concentrations of amisulpride and total radioactivity were measured in plasma, whole blood, urine and feces at various time points up to 168 hrs after dosing. Metabolites detected in plasma, urine and feces were characterized using liquid chromatography tandem mass spectrometry (LC-MS/MS) with in-line radiometric detection.

Results

The mean recovery of radioactivity in excreta was 96.4% (range 92.0–98.5%), of which 73.6% (range 70.6–79.2%) was recovered from urine and 22.8% (range 18.9–25.7%) from feces. Four metabolites of amisulpride were detected in urine, representing 15.0% of the excreted dose; three of these were also present in feces, representing 6.1% of the excreted dose. No metabolites were detected in plasma. Excretion was initially rapid, with about two-thirds of the drug-related material eliminated within 12 hrs, primarily in the urine. A second, slower phase of excretion was predominantly fecal and was essentially complete by 96 hrs after dosing. The terminal plasma elimination half-life of parent amisulpride was 3.7 hrs and that of total ¹⁴C-labeled drug material was 4.2 hrs.

Conclusion

Intravenous amisulpride undergoes limited metabolism and is excreted primarily via the renal route.

Clinical trial registry number

ClinicalTrials.gov NCT02881840.

Potential Drug-drug Interactions in Acute Ischemic Stroke Patients at the Neurological Intensive Care Unit

Background

Clinically relevant potential drug-drug interactions are considered preventable adverse drug reactions.

Objective

The aim of this study was to ascertain the frequency of potential drug-drug interactions in acute ischemic stroke patients and to explore factors associated with occurrence of potentially contraindicated drug-drug interactions.

Methods

This observational retrospective cohort and nested case-control study was carried out among patients treated for acute ischemic stroke at the Neurological Intensive Care Unit in the Clinical Centre Kragujevac, Serbia. The potentially drug-drug interactions for each day of hospitalization were identifi ed using Micromedex® soft ware. Based on the existence or absence of potentially contraindicated drug-drug interactions, the participants were divided into a group of cases (n=111) and the control group (n=444).

Results

A total of 696 patients were analysed. All patients had a minimum of one potential drug-drug interaction during hospitalization. The most common drugs involved in potential drug-drug interactions were aspirin (8.02%), diclofenac (7.49%) and warfarin (7.14%). The number of medications prescribed for simultaneous use during hospitalisation and the use of antipsychotics in therapy signifi cantly increased the likelihood of potentially contraindicated drug-drug interactions aft er adjustment by means of logistic regression for 1.2 and 3 times, respectively.

Conclusions

This study suggests that patients with acute ischemic stroke are frequently exposed to potential drug-drug interactions. It is essential to identify potentially drug-drug interactions in these patients as early as possible in order to prevent adverse drug reactions and ensure safe recovery. Besides, full attention should be paid when adding each new medication in therapy, particularly when a neurologist decides to prescribe antipsychotics, such as risperidone.

What are the Predictive Factors for the Treatment Outcomes in Multi Drug Poisoning Including Antidepressants/Antipsychotic Drugs?

Background

There have been studies on the outcome of acute intoxication with antidepressants or antipsychotics. We performed outcome prediction analysis in acute poisoning patients with antidepressants/antipsychotics with or without combination with other drugs.

Materials and Methods

A cross-sectional study was performed in Khorshid (PBUH) University Hospital affiliated with Isfahan University of Medical Sciences from March 2016 to May 2017. Patients with acute poisoning ingested antidepressants and antipsychotics with or without other drugs were included in the study. The outcome was categorized as survived without complications and complications/death. Binary regression analysis was performed for outcome prediction.

Results

The data from 239 patients were analyzed. Most of the patients were female (68.2%), 5.9% of patients admitted to the Intensive Care Unit. About 94.99% of patients survived without complications. There was a significant difference between patients with and without complications with respect to the level of consciousness, hypotension, seizure, electrocardiography findings, pulse rate after 24 hours (h) of admission, and need to endotracheal intubation (P < 0.0001). Binary logistic regression analysis showed admission level of consciousness (stupor/coma) (odds ratio [OR] =8.07; P = 0,005), hypotension (OR = 12.16; P = 0.001), seizure (OR = 11.15; P = 0.009), tachycardia after 24 h of admission (OR = 22.50; P = 0.003), and need for endotracheal intubation (OR = 10.47; P = 0.002) were determinant factors in outcome prediction.

Conclusions

Stupor/coma and hypotension were the predictive factors for outcome. Patients with seizure and tachycardia after 24 h of admission; and those intubated and received mechanical ventilation had a higher chance of complications.

High Doses of Drugs Extensively Metabolized by CYP3A4 Were Needed to Reach Therapeutic Concentrations in Two Patients Taking Inducers

INTRODUCTION

In the last 20 years of clinical practice, the senior author has identified these 2 rare cases in which the patients needed extremely high doses of drugs metabolized by CYP3A4 to reach and maintain serum therapeutic concentrations.

METHODS

The high metabolic ability of these 2 patients was demonstrated by the low concentration-to-dose ratios (C/D ratios) of several drugs metabolized by CYP3A4.

RESULTS

Case 1 was characterized by a history of high carbamazepine doses (up to 2,000mg/day) and needed 170 mg/day of diazepam in 2 days to cooperate with dental cleaning. The high activity of the CYP3A4 isoenzyme was manifested by fast metabolism for quetiapine and diazepam, which took more than 1 year to normalize after the inducer, phenytoin, was stopped. Case 2 was also very sensitive to CYP3A4 inducers as indicated by very low C/D ratios for carbamazepine, risperidone and paliperidone. The carbamazepine (2,800 mg/day) and risperidone (20 mg/day) dosages for this second patient are the highest doses ever seen for these drugs by the senior author. Risperidone induction appeared to last for many months and metabolism was definitively normal 3 years after stopping carbamazepine. On the other hand, olanzapine C/D ratios were normal for induction.

CONCLUSIONS

The literature has never described similar cases of very high doses of drugs metabolized by CYP3A4. We speculate that these 2 patients may have unusual genetic profiles at the nuclear receptor levels; these receptors regulate induction of drugs.

Molecular targets of atypical antipsychotics: From mechanism of action to clinical differences

The introduction of atypical antipsychotics (AAPs) since the discovery of its prototypical drug clozapine has been a revolutionary pharmacological step for treating psychotic patients as these allow a significant recovery not only in terms of hospitalization and reduction in symptoms severity, but also in terms of safety, socialization and better rehabilitation in the society. Regarding the mechanism of action, AAPs are weak D₂ receptor antagonists and they act beyond D₂ antagonism, involving other receptor targets which regulate dopamine and other neurotransmitters. Consequently, AAPs present a significant reduction of deleterious side effects like parkinsonism, hyperprolactinemia, apathy and anhedonia, which are all linked to the strong blockade of D₂ receptors. This review revisits previous and current findings within the class of AAPs and highlights the differences in terms of receptor properties and clinical activities among them. Furthermore, we propose a continuum spectrum of "atypia" that begins with risperidone (the least atypical) to clozapine (the most atypical), while all the other AAPs fall within the extremes of this spectrum. Clozapine is still considered the gold standard in refractory schizophrenia and in psychoses present in Parkinson's disease, though it has been associated with adverse effects like agranulocytosis (0.7%) and weight gain, pushing the scientific community to find new drugs as effective as clozapine, but devoid of its side effects. To achieve this, it is therefore imperative to characterize and compare in depth the very complex molecular profile of AAPs. We also introduce relatively new concepts like biased agonism, receptor dimerization and neurogenesis to identify better the old and new hallmarks of "atypia". Finally, a detailed confrontation of clinical differences among the AAPs is presented, especially in relation to their molecular targets, and new means like therapeutic drug monitoring are also proposed to improve the effectiveness of AAPs in clinical practice.

Prolactin levels: sex differences in the effects of risperidone, 9-hydroxyrisperidone levels, CYP2D6 and ABCB1 variants

AIM

The role of sex on the association of plasma prolactin levels with risperidone (R) and 9-hydroxyrisperidone (9-OHR) concentrations is investigated.

METHODS

Plasma R and prolactin concentrations, CYP2D6 and exon 21 and 26 ABCB1 gene variants were studied in 110 patients.

RESULTS

In females, a 1 ng/ml increase in R levels was associated with a significant 1.02% increase in prolactin levels. In males, a 1 ng/ml increase in 9-OHR levels was associated with a significant 1.18% increase in prolactin levels. ABCB1 haplotype 12 had significant but opposite effects in males and females. In the combined sample, 9-OHR, but not R levels had significant effects on prolactin levels.

CONCLUSION

Genes had sex-specific effects on risperidone-associated prolactin elevations.

Quetiapine-induced cervical dystonia

OBJECTIVE

Our objective was to report and describe a case of quetiapine-induced dystonia in an older lady with psychosis. Quetiapine is a second-generation antipsychotic and known to be rare in causing extrapyramidal side effects with rates similar to placebo.

CONCLUSIONS

There have been few documented cases of quetiapine-induced dystonia. It is important to be vigilant and consider the development of dystonia in patients who may not fit the typical risk profile.