Vol. 7, Issue 2, Part C (2025)

Antipsychotic medications, introduced in the 1950s, remain the cornerstone of treatment for psychiatric disorders such as schizophrenia, bipolar disorder, and obsessive-compulsive disorder. However, high discontinuation rates (32-74%) due to adverse effects highlight the need for individualized treatment strategies. The wide interindividual variability in treatment response is influenced by both pharmacokinetic and pharmacodynamic factors. Pharmacogenetics offers a precision medicine approach by guiding drug selection and dosing based on genetic variations, particularly in cytochrome P450 (CYP) enzymes and neurotransmitter receptor genes. CYP2D6, CYP1A2, and CYP3A subfamilies are key determinants of antipsychotic metabolism, while genetic polymorphisms in dopamine and serotonin receptors (e.g., DRD2, HTR2A, HTR2C) influence therapeutic outcomes and risk of side effects such as tardive dyskinesia and akathisia. Evidence from clinical and pharmacogenetic studies demonstrates strong associations between genetic variants and altered plasma drug levels, treatment response, and extrapyramidal symptoms. Importantly, pharmacogenetic-guided therapy has shown cost-effectiveness in psychiatry, although routine clinical adoption remains limited due to turnaround time and implementation barriers. Advances in rapid genomic testing, polygenic risk scoring, and integration with clinical data hold promise for delivering near real-time recommendations, thereby improving treatment outcomes and reducing healthcare costs. This review highlights the current evidence, clinical implications, and future prospects of pharmacogenetics in optimizing antipsychotic therapy.