Ribavirin 5''-monophosphate inhibits viral DNA and RNA replication in vitro via the strong competitive inhibition of inosine monophosphate dehydrogenase (IMPDH), with a reported Ki value of 270 nM, and thus inhibits guanosine triphosphate synthesis. This agent, a metabolite of the prodrug ribavirin , exhibits broad-spectrum antiviral activity, particularly against myxoviruses. The antiviral effects of ribavirin require conversion to the monophosphate form via adenosine kinase. The anti-HIV activity of ribavirin in cultured human lymphocytes, as well as the anti-influenza activity of this prodrug in MDCK cells, have been attributed to ribavirin 5''-monophosphate.
