Oravir; Famvir|Famciclovir is a guanosine nucleoside analog that exhibits antiviral activity. Clinically, famciclovir is used to treat herpes virus infections; it is a prodrug of penciclovir.|C14H19N5O4|321.33||Ambient|Soluble in acetone or methanol. Slightly soluble in ethanol or isopropylalcohol.