Deuterium substitution enhances drug metabolic stability and efficacy across oncology, rare, and CNS diseases.

Drug discovery faces significant hurdles in optimizing therapeutic efficacy and safety, often limited by rapid metabolic degradation and suboptimal pharmacokinetic (PK) profiles. Traditional small molecule drugs frequently exhibit short half-lives, necessitating frequent dosing and increasing the risk of off-target effects. The deuterium kinetic isotope effect (KIE) offers a unique strategy to overcome these challenges by strengthening carbon-deuterium bonds, thereby slowing enzymatic metabolism without altering pharmacological activity. This approach aims to enhance drug stability and extend systemic exposure, addressing a critical gap in developing more effective and tolerable treatments.

This comprehensive review systematically discussed recent innovations in site-selective deuteration and the fundamental principles underpinning the deuterium kinetic isotope effect (KIE). It analyzed the profound effects of deuterium substitution on drug metabolism, toxicity, and blood-brain barrier (BBB) penetration. The authors illustrated novel implications across various therapeutic areas, including oncology, rare diseases, and central nervous system (CNS) disorders. Furthermore, the review integrated deuterated chemistry with emerging modalities such as proteolysis-targeting chimaeras (PROTACs), peptides, and nucleic acid therapeutics, providing a broad overview of its applicability.

The review highlighted that deuterium substitution leverages the KIE to significantly improve drug metabolic stability by strengthening C-D bonds, leading to enhanced pharmacokinetic profiles and prolonged therapeutic action. This mechanism reduces the rate of enzymatic cleavage, extending a drug's half-life in vivo. Deuterium incorporation was shown to reduce drug toxicity by minimizing the formation of reactive metabolites, while also modulating BBB penetration, which is crucial for CNS drug development. The review detailed how site-selective deuteration can be precisely engineered to optimize drug properties for specific indications, from cancer therapies to treatments for neurodegenerative conditions. It also underscored the versatility of deuterium in combination with advanced therapeutic modalities, opening new avenues for drug design.

Clinically, deuterated drugs like donafenib and deutetrabenazine have already demonstrated significant efficacy, validating the approach's potential.