Proguanil-d6 hydrochloride is the deuterium labeled Proguanil hydrochloride (HY-B0806A). Proguanil hydrochloride, an antimalarial prodrug, is metabolized to the active metabolite Cycloguanil (HY-12784). Proguanil hydrochloride is a dihydrofolate reductase (DHFR) inhibitor[2].In Vitro: 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.