Unveiling the power of deuterium in drug discovery: a comprehensive overview

Deuterium, the heavy isotope of hydrogen, has unfolded as a cornerstone in modern drug discovery due to its potential to influence metabolic stability and pharmacokinetic behavior. The deuterium kinetic isotope effect (KIE), which strengthens carbon–deuterium bonds, make it possible to improve therapeutic efficacy while maintaining pharmacological activity. Although some deuterated drugs, notably donafenib and deutetrabenazine, have demonstrated clinically significant efficacy, their limited use is an effect of ongoing challenges with metabolic switching and species-specific variation, as well as inadequate mechanistic understanding. This review presents a systematic discussion of the recent innovations in site-selective deuteration, the principles that underpin the KIE process, and the effects of deuterium substitution on drug metabolism, toxicity, and blood–brain barrier penetration. It illustrates novel implications in oncology, rare diseases, and central nervous system disorders, as well as the integration of deuterated chemistry with modalities such as proteolysis-targeting chimaeras, peptides, and nucleic acid therapeutics. Furthermore, the review's discussion includes the current challenges, synthesis, analytical limits, and regulatory considerations that influence further development. Overall, the review offers a strategic roadmap for utilizing deuterium-enabled molecular engineering to accelerate the development of next-generation precision medicine, guiding rational design, innovation toward safer, longer-lasting, and more effective treatments.