Stable heavy isotopes of hydrogen, carbon, and other elements have been incorporated into drug molecules, largely as tracers for quantitation during the drug development process. Deuteration has gained attention because of its potential to affect the pharmacokinetic and metabolic profiles of drugs[1].
References:
[1]. Russak EM, et al. Impact of Deuterium Substitution on the Pharmacokinetics of Pharmaceuticals. Ann Pharmacother. 2019;53(2):211-216.
[2]. Biot C, et al. Synthesis and antimalarial activity in vitro of potential metabolites of ferrochloroquine and related compounds. Bioorg Med Chem. 1999 Dec;7(12):2843-7.
[3]. Essien EE, et al. Effects of chloroquine and didesethylchloroquine on rabbit myocardium and mitochondria. J Pharm Pharmacol. 1986 Jul;38(7):543-6.