Ranbaxy Laboratories has received tentative approval from the US Food and Drug Administration to manufacture and market the generic version of Roche's Valcyte (valganciclovir hydrochloride Tablets, 450 mg), a drug used for treatment of cytomegalovirus retinitis in patients afflicted with AIDS. Being the first company to apply for the marketing the medicine in the US, Ranbaxy is expected to get 180-days exclusive marketing opportunity after the patent protection on the drug expires. Roche's patent for Valcyte will end in 2015. Roche has already sought legal action against Ranbaxy citing alleged patent infringement on valganciclovir. According to market research agency IMS, the total annual market sales for valganciclovir HCl tablets for March 2008 was $239 million. The drug is also indicated for preventing cytomegalovirus (CMV) disease in kidney, heart and kidney-pancreas transplant patients at high risk (donor CMV seropositive/recipient CMV seronegative [(D+/R-)]). Ranbaxy will launch valganciclovir after receiving final approval and resolution of litigation, Bill Winter, vice-president, Tradey in USA Ranbaxy is known to be having 18 such first to file opportunities with a significant market size of over $ 27 billion, at innovator prices. While patent disputes over five of them have been settled, four, including vulganciclovir, are under litigations.