英文别名5-(5-(2-Chloroacetyl)-2-ethoxyphenyl)-1-methyl-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-7(6H)-one; Sildenafil Impurity 5; Sildenafil Chloroacetyl Impurity; 5-[5-(2-chloroacetyl)-2-ethoxyphenyl]-1-methyl-3-propyl-4H-pyrazolo[4,3-d]pyrimidin-7-one; Sildenafil impurities 5; 7H-Pyrazolo[4,3-d]pyrimidin-7-one, 5-[5-(2-chloroacetyl)-2-ethoxyphenyl]-1,6-dihydro-1-methyl-3-propyl- 
