Pharmacogenomic

Pharmacogenomics is a field of study that examines how genetic variation influences an individual's response to medicines. It seeks to optimize drug therapy by accounting for genetic factors that affect drug absorption, metabolism, distribution, and action. As a facet of precision medicine, pharmacogenomics aims to tailor drug choice and dosing to maximize efficacy while minimizing adverse effects.

Pharmacogenomics includes both genome-wide analyses and gene-specific investigations. Pharmacogenetics historically focused on single genes, whereas pharmacogenomics tends to consider the broader genomic context and multiple gene–drug interactions that contribute to drug response.

Common examples encompass warfarin dosing guided by variants in VKORC1 and CYP2C9, which influence dose requirements and bleeding risk; metabolism of certain drugs by CYP2D6 such as codeine and various antidepressants; TPMT variants that affect toxicity with thiopurines; and HLA alleles associated with hypersensitivity reactions to particular medications, such as carbamazepine or abacavir in susceptible populations.

Applications of pharmacogenomics include guiding initial drug choice and dosing, preemptive testing in high-risk patients, informing drug development, and supporting regulatory labeling and guidelines. Clinical resources like the Clinical Pharmacogenetics Implementation Consortium (CPIC) and the Dutch Pharmacogenetics Working Group (DPWG) provide practice guidelines for applying genetic information to prescribing.

Limitations and challenges include that genetics explain only part of interindividual variability, with environmental factors, age, organ function, drug interactions, and polygenic effects also shaping outcomes. Implementation requires infrastructure, cost considerations, and attention to privacy and equity. Ongoing research expands actionable gene–drug pairs and integration into electronic health records.