Pharmacogenetics and the Blood–Brain Barrier: A Whirlwind Tour of Potential Clinical Utility

Genetic factors influence medication response (pharmacogenetics), affecting the pharmacodynamics and pharmacokinetics of many medicaments used in clinical care. The ability of medications to cross the blood–brain barrier (BBB) represents a critical putative factor in the effectiveness and tolerability of various medications relevant to central nervous system disorders (CNS), cancer, and broader medical conditions at a pharmacokinetic (dosing) level. Pharmacogenetics has the potential to personalise medicine to a greater extent than has been possible, with the potential to help reduce heuristic delays to effective tolerable pharmacotherapy. Here, we critically examine and summarise the evidence, particularly for ABCB1 polymorphisms associated with drug transportation and other clinical relevance. These transporters appear to have a role in BBB pharmacogenetics and may indicate new avenues of research that extend beyond the current paradigm of CYP450 polymorphisms. We identify some of the most promising variants for clinical translation while spotlighting the complexities of the involved systems and limitations of the current empirical literature.