Proguanil-d6 HCl is a deuterated compound of Proguanil HCl. Proguanil HCl has a CAS number of 637-32-1. Proguanil Hydrochloride is a biguanide compound which metabolizes in the body to form cycloguanil, an anti-malaria agent.Upon hydrolysis, proguanil is converted to its active cyclic triazine metabolite, cycloguanil, by a cytochrome P450 dependent reaction. Cycloguanil selectively inhibits the bifunctional dihydrofolate reductase-thymidylate synthase of plasmodium parasite, thereby disrupting deoxythymidylate synthesis and ultimately blocking DNA and protein synthesis in the parasite.