2-[(2-Amino-6-oxo-1,6-dihydro-9H-purin-9-yl)methoxy]ethyl N-Methyl-L-valinate; 2-((2-Amino-6-oxo-1,6-dihydro-9H-purin-9-yl)methoxy)ethyl Methyl-L-valinate; N-Methyl Valacyclovir; Acyclovir N-Methyl-L-valinate; Valaciclovir EP Impurity C