Famciclovir N7-Isomer with CAS No: 131266-15-4 is an impurity standard of Famciclovir. Famciclovir is an antiviral medication used to treat infections caused by herpes viruses, including genital herpes, shingles (herpes zoster) and cold sores (herpes labialis).Famciclovir is usually available in tablet form. Buy high quality Famciclovir N7-Isomer from Molsyns Research. Molsyns Research is one of the leading manufacturer and exporter of Famciclovir N7-Isomer