Pre-prescription testing in psychiatry: An overview

Abstract

Drug therapy 'tailored' towards an individual based on his/her genetic profile is becoming increasingly popular in the era of personalised medicine. Pre-prescription testing which enables this, exploits the link between a relevant set of genetic variants and drug metabolism profile to maximise drug efficacy and lower the risk of adverse drug reactions. Since the conception over 50 years ago that drug response might be linked to underlying genetic makeup, the science around this field has evolved rapidly across a wide range of drugs including antipsychotics. Over 80% of both typical and atypical antipsychotics are known to be metabolised by phase-I drug metabolising enzymes such as cytochrome P450 (CYP450) family of genes which harbour extensive genetic variations. This has encouraged variant testing in these genes among patients with neuropsychiatric disorders. A confluence of accelerated variant discovery and next generation sequencing offers a fast and cost-effective approach. However, genomic literacy among the end users, i.e., the psychiatrists, patients, and their primary caregivers remains low, posing a major hindrance in the realisation of this pharmacogenetic goal. A well-oiled, multi-disciplinary machinery comprising of researchers, psychiatrists, and genetic counsellors would be the key for optimal dissemination of this intervention. This review presents a broad conceptual background of pharmacogenetics/pharmacogenomics, its potential in psychiatry in particular, together with clinical evidence, and the accompanying challenges for its effective implementation in clinical settings.