Pharmacogenetics of antipsychotic treatment response and side effects

Tardive Dyskinesia with Antipsychotic Medication in Children and Adolescents: A Systematic Literature Review

BACKGROUND

Tardive dyskinesia (TD) is a persisting, and potentially irreversible, movement disorder associated with treatment with dopamine receptor antagonists. Few data are available on the risk of TD in children and adolescents treated with antipsychotic medication.

OBJECTIVE

To review the literature on incidence, risk factors, and treatment options for antipsychotic-associated TD in children and adolescents (aged < 18 years).

METHODS

Relevant articles were identified through a systematic search of Embase and Medline performed in January 2024. Methodological quality was assessed using the Newcastle-Ottawa Scale and Joanna Briggs Institute Critical Appraisal tools.

RESULTS

Thirteen studies were identified. The reported TD point prevalence was 5-20%, with higher rates in studies involving typical antipsychotics. Lower estimates (around 1%) emerged from analyses of clinical database data suggesting underdiagnosis in clinical practice. Risk factors included treatment with typical antipsychotics, higher doses, longer duration of exposure, older age, female gender, higher baseline Abnormal Involuntary Movements Scale (AIMS) scores, intellectual impairment, and perinatal complications.

CONCLUSION

Although relatively few cases have been reported in children and adolescents, TD remains a risk in this population. Individuals receiving antipsychotics should be monitored carefully for the emergence of abnormal movements. Other than dose reduction, discontinuation, or switch to a lower-risk antipsychotic, few interventions have demonstrated efficacy. The strongest evidence for pharmacological treatment is for VMAT-2 inhibitors (valbenazine and deutetrabenazine), but these drugs are not licensed for use in children. To reduce risk, antipsychotics should be prescribed only if necessary, at the minimum effective dose and for the minimum necessary duration.

Prediction of antipsychotics efficacy based on a polygenic risk score: a real-world cohort study

Background: Response to antipsychotics is subject to a wide interindividual variability, due to genetic and non-genetic factors. Several single nucleotide polymorphisms (SNPs) have been associated with response to antipsychotics in genome-wide association studies (GWAS). Polygenic risk scores (PRS) are a powerful tool to aggregate into a single measure the small effects of multiple risk alleles. Materials and methods: We studied the association between a PRS composed of SNPs associated with response to antipsychotics in GWAS studies (PRSresponse) in a real-world sample of patients (N = 460) with different diagnoses (schizophrenia spectrum, bipolar, depressive, neurocognitive, substance use disorders and miscellaneous). Two other PRSs composed of SNPs previously associated with risk of schizophrenia (PRSschizophrenia1 and PRSschizophrenia2) were also tested for their association with response to treatment. Results: PRSresponse was significantly associated with response to antipsychotics considering the whole cohort (OR = 1.14, CI = 1.03-1.26, p = 0.010), the subgroup of patients with schizophrenia, schizoaffective disorder or bipolar disorder (OR = 1.18, CI = 1.02-1.37, p = 0.022, N = 235), with schizophrenia or schizoaffective disorder (OR = 1.24, CI = 1.04-1.47, p = 0.01, N = 176) and with schizophrenia (OR = 1.27, CI = 1.04-1.55, p = 0.01, N = 149). Sensitivity and specificity were sub-optimal (schizophrenia 62%, 61%; schizophrenia spectrum 56%, 55%; schizophrenia spectrum plus bipolar disorder 60%, 56%; all patients 63%, 58%, respectively). PRSschizophrenia1 and PRSschizophrenia2 were not significantly associated with response to treatment. Conclusion: PRSresponse defined from GWAS studies is significantly associated with response to antipsychotics in a real-world cohort; however, the results of the sensitivity-specificity analysis preclude its use as a predictive tool in clinical practice.

The role of alcohol intake in the pharmacogenetics of treatment with clozapine

Clozapine (CLZ) is an atypical antipsychotic reserved for patients with refractory psychosis, but it is associated with a significant risk of severe adverse reactions (ADRs) that are potentiated with the concomitant use of alcohol. Additionally, pharmacogenetic studies have explored the influence of several genetic variants in CYP450, receptors and transporters involved in the interindividual response to CLZ. Herein, we systematically review the current multiomics knowledge behind the interaction between CLZ and alcohol intake, and how its concomitant use might modulate the pharmacogenetics. CYP1A2*1F, *1C and other alleles not yet discovered could support a precision medicine approach for better therapeutic effects and fewer CLZ ADRs. CLZ monitoring systems should be amended and include alcohol intake to protect patients from severe CLZ ADRs.

Current and emerging long-acting antipsychotics for the treatment of schizophrenia

Introduction: In this review, the authors discuss the role of long-acting injectable antipsychotics (LAIs) for schizophrenia, focusing on the effectiveness and new perspectives introduced by such treatment strategy. Despite their promising pharmacokinetic features and their potential advantages in medication adherence, clinical outcomes, and medical costs, LAIs are not habitually presented as an option for patients, especially in the early phase of schizophrenia.Areas covered: This review explores the panorama of available LAIs for the treatment of schizophrenia, first-episode of psychosis, approved indications, medical costs, medication adherence, side effects, effectiveness and differences between first-generation (FGA)-LAIs and second-generation (SGA)-LAIs.Expert Opinion: LAIs differ in terms of specific indications, approved injection sites, needle size, injection volume, injection interval as well as potential drug-drug interactions, and commonly reported adverse reactions. The approved indications have expanded beyond schizophrenia to include bipolar and schizoaffective disorder. SGA-LAIs are often preferred to FGA-LAIs. FGA-LAIs although are less chosen in new patients due to the induction of cognitive and extrapyramidal side effects, even if, on the other hand, many SGA-LAIs are burden by hyperprolactinemia and weight gain. After a review of the available evidence, insight is provided into the potential and current therapeutic opportunities offered by LAI antipsychotic formulations.

Impact of CYP1A2 genetic polymorphisms on pharmacokinetics of antipsychotic drugs: a systematic review and meta-analysis

OBJECTIVE

To determine the impact of CYP1A2 genetic polymorphisms on the pharmacokinetics of CYP1A2-metabolized antipsychotic drugs in humans by means of systematic review and meta-analysis.

METHOD

A systematic search was conducted in PubMed and Scopus databases as of June 26, 2018. Studies reporting the pharmacokinetic parameters of CYP1A2-metabolized antipsychotic drugs in individuals who were genotyped for CYP1A2 genetic polymorphisms were retrieved. Pharmacokinetic parameters of individuals who have mutant alleles of a CYP1A2 genetic polymorphism were compared with the wild-type individuals. Pooled-effect estimates, presented as standardized mean difference, were calculated by means of the fixed-effect or random-effects model, as appropriate.

RESULTS

Ten studies involving 872 clozapine users, seven studies involving 712 olanzapine users, and two studies involving 141 haloperidol users were included. All but one study reported no associations between any CYP1A2 genetic polymorphisms and the pharmacokinetics of CYP1A2-metabolized antipsychotic drugs. The pooled-effect estimates through meta-analyses of seven studies demonstrated no significant associations between the -163C>A or -2467delT polymorphism and clozapine or olanzapine concentrations in the blood.

CONCLUSIONS

This study suggests that CYP1A2 genetic polymorphisms have no significant impact on the pharmacokinetics of CYP1A2-metabolized antipsychotic drugs. CYP1A2 genotyping may have no clinical implications for personalized dosing of CYP1A2-metabolized antipsychotic drugs.

[Pharmacogenetic-based risk assessment of antipsychotic-induced extrapyramidal symptoms]

"Typical" antipsychotics remain the wide-prescribed drugs in modern psychiatry. But these drugs are associated with development of extrapyramidal symptoms (EPS). Preventive methods of EPS are actively developed and they concentrate on personalized approach. The method of taking into account genetic characteristics of patient for prescribing of treatment was proven as effective in cardiology, oncology, HIV-medicine. In this review the modern state of pharmacogenetic research of antipsychotic-induced EPS are considered. There are pharmacokinetic and pharmacodynamic factors which impact on adverse effects. Pharmacokinetic factors are the most well-studied to date, these include genetic polymorphisms of genes of cytochrome P450. However, evidence base while does not allow to do the significant prognosis of development of EPS based on genetic testing of CYP2D6 and CYP7A2 polymorphisms. Genes of pharmacodynamics factors, which realize the EPS during antipsychotic treatment, are the wide field for research. In separate part of review research of such systems as dopaminergic, serotonergic, adrenergic, glutamatergic, GABAergic, BDNF were analyzed. The role of oxidative stress factors in the pathogenesis of antipsychotic-induced EPS was enough detailed considered. The system of those factors may be used for personalized risk assessment of antipsychotics' safety in the future. Although there were numerous studies, the pharmacogenetic-based prevention of EPS before prescribing of antipsychotics was not introduced. However, it is possible to distinguish the most perspectives markers for further research. Furthermore, brief review of new candidate genes provides here, but only preliminary results were published. The main problem of the field is the lack of high- quality studies. Moreover, the several results were not replicated in repeat studies. The pharmacogenetic-based research must be standardized by ethnicity of patients. But there is the ethnical misbalance in world literature. These facts explain why the introduction of pharmacogenetic testing for risk assessment of antipsychotic-induced EPS is so difficult to achieve.

Role of ethnicity in antipsychotic-induced weight gain and tardive dyskinesia: genes or environment?

Aim: This study explored the role of self-reported ethnicity and genetic ancestry on antipsychotic (AP)-induced weight gain and tardive dyskinesia (TD) in schizophrenia. Patients & methods: Ethnicity was determined by self-report as well as Structure analysis of 190 SNPs selected from HapMap3, genotyped using a customized Illumina BeadChip. Age, gender, baseline weight and AP response using Brief Psychiatric Rating Scale were assessed. Multivariate regression models for AP-induced weight gain and TD, based on the Abnormal Involuntary Movement Scale were constructed. Results: African–American ethnicity (self-report, p = 0.021 and Structure analysis, p = 0.042) predicted AP-induced weight gain but not TD (self-report, p = 0.408 and Structure analysis, p = 0.714). Conclusion: Self-reported African–American ethnicity seemed to better predict AP-induced weight gain in schizophrenia compared with genetic ancestry, suggesting a possible role of environmental in addition to genetic factors. Future larger studies are needed to clarify specific gene–environment mechanisms mediating the effect of ethnicity on AP-induced weight gain.

Original submitted 1 January 2013; Revision submitted 17 June 2013