Pharmaceutical Science: Research Trends and Challenges Vol. 1

Pharmacogenomics is one of the most mature genomic applications within personalised medicine, yet its translation into routine care remains uneven. This critical narrative review examines the evidential, technical and organisational conditions under which inherited genomic variation can improve medication selection, dosing and safety. Literature published from 1997 to 31 May 2026 was identified through PubMed/MEDLINE, Crossref metadata verification, the Clinical Pharmacogenetics Implementation Consortium and ClinPGx/PharmGKB resources, regulatory information, and backward and forward citation searching. Evidence was appraised according to analytical validity, genotype-to-phenotype reliability, clinical validity, clinical utility, study design, population representation, implementation feasibility and economic transferability. The strongest evidence concerns prevention of severe, mechanism-linked toxicity, particularly HLA-associated hypersensitivity and selected metabolic defects, where the causal chain from variant to phenotype and therapeutic action is comparatively direct. Evidence is also persuasive for several context-specific dosing or drug-selection decisions, including thiopurines, fluoropyrimidines, clopidogrel and selected statins. By contrast, results for warfarin and combinatorial psychiatric testing show that biological plausibility and altered prescribing do not necessarily yield large or persistent patient-level benefits. Pre-emptive panel testing can reduce clinically relevant adverse reactions, but its effectiveness depends on laboratory completeness, harmonised phenotype translation, rapid result availability, electronic decision support, clinician uptake and longitudinal data portability. Current evidence is constrained by ancestry imbalance, incomplete interrogation of complex pharmacogenes, proprietary algorithms, inconsistent outcomes and economic models that often depend on local assumptions. Pharmacogenomics should therefore be treated neither as a universal replacement for clinical judgement nor as a collection of isolated genetic tests. Its most defensible role is as durable prescribing infrastructure integrated with phenotype, co-medication, organ function, treatment indication and patient preference. Progress will require ancestry-diverse prospective studies, standardised test content, transparent algorithms, learning health-system evaluation and governance that prevents genomic benefit from widening existing inequities.