Chantix Patent in Post Grant Proceeding

Pfizer is involved in a post-grant opposition proceeding for its patent covering hugely popular antismoking drug Chantix. The post-grant opposition is filed by Dr. Reddy’s Laboratories against the Indian Patent No. 204091 (the ‘091 patent) covering tartrate salt of Varenicline, the active ingredient of Chantix. The ‘091 patent is issued against the Application No. 863/MUMNP/2003 and corresponding of Orange Book listed US Patent Nos. 6,890,927 and 7,265,119. Last year in February, Pfizer launched the Varenicline prescription drug in India under the brand name Champix. However, in past there had been an alarming and strong adverse reports related with the use of Varenicline causing a wide spectrum of injuries, including serious accidents and falls, potentially lethal cardiac rhythm disturbances, severe skin reactions, acute myocardial infarction, seizures, diabetes, psychosis, aggression and suicide (read here). In November 2007, the United States FDA issued a safety alert for Varenicline reporting cases of suicidal thoughts and aggressive and erratic behavior in patients taking Chantix. Report also described Chantix affecting patients’ ability to drive or operate machinery. Later in May 2008, the United States FDA issued another alert highlighting important revisions made to the prescribing information for Chantix. Earlier this year in February, CBC News reported that Health Canada received 818 complaints for Canadian patients, many of them reporting mood swings, depression or suicidal thoughts.

We really wonder and concern whether the Indian Drug Regulatory had taken the Varenicline adverse reports seriously enough (read Mint story) and into consideration before giving marketing approval in India. Particularly considering that in India, it is not unusual to buy prescription drugs without doctor’s prescription – Varenicline may seriously pose high risk to Indian patients. And what if Varenicline generic versions also steps in?