Ranbaxy has yet again made Pfizer to defend their patents for blockbuster drug products now adding anti-cholesterol drug Caduet in their ongoing list of patent litigations. Pfizer filed a patent infringement suit against Ranbaxy in response to Ranbaxy’s ANDA submission with the US FDA for marketing approval of generic Caduet before expiry of Orange Book listed patents. Caduet is combination of amlodipine besylate and atorvastatin calcium. In its complaint, Pfizer alleged that Ranbaxy’s ANDA products would infringe Pfizer’s patents for Caduet. However, Ranbaxy is believed to have first-to-file status for Caduet.