New Delhi’s Ranbaxy Laboratories has launched a generic version of GlaxoSmithKline’s (GSK) herpes treatment Valtrex in the US.

According to a company spokesperson Ranbaxy has launched the generic valacyclovir hydrochloride with a 180-day marketing exclusivity in 500mg and 1g tablet form.

The 180-day marketing exclusivity will allow Ranbaxy to be the only company other than GSK to market the drug after the patent expires.

The patent for Valtrex espires in 2009 after it was launched in 1995 to treat genital herpes, cold sores and shingles.

Ranbaxy had settled a patent dispute with GSK for the drug in 2007.