2-Amino-7-[(2-hydroxyethoxy)methyl]-1,7-dihydro-6H-purin-6-one; Aciclovir N7-Isomer; 2-Amino-7-(2-hydroxy-ethoxymethyl)-1,7-dihydro-purin-6-one; 2-Amino-7-(2-hydroxyethoxymethyl)-3H-purin-6-one; 2-Amino-7-[(2-hydroxyethoxy)methyl]-6,7-dihydro-1H-purin-6-one; Acyclovir N7-Isomer; 2-Amino-7-[(2-hydroxyethoxy)methyl]-1,7-dihydro-6H-purin-6-one (USP)