Pfizer’s high profile anti-smoking drug Champix is facing patent uncertainty in India as Dr Reddy’s has filed a post grant opposition against selling the drug in India.
Champix, which contains varenicline that helps smokers kick the butt, in India by Pfizer in February last year.
However, India’s leading generic maker Dr Reddy’s questioned the validity of the patent in post-grant opposition filed against ‘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.
Post-grant opposition is a proceeding allowed in the Indian patent system to dispute the validity of a patent by a third party, which is already granted.
Pfizer’s non-nicotine smoking cessation drug Champix was priced at Rs 9,500 for a 12-week therapy in India.
Pfizer launched Champix in Indian market in less than two years of its launch in the US,despite serious concerns about the safety of the drug.
Varenicline is a partial agonist of one of the nicotinic acetylcholine receptors in the brain and nervous system,1 and currently the only marketed and approved drug with this mechanism of action.
The FDA approved varenicline in May 2006 under the brandname Chantix after granting it a priority review. Since the approval varenicline is suspected in various adverse drug event reports of including inducing suicidal thoughts.
Among the other harmful side-effects of varenicline are serious accidents and falls, potentially lethal cardiac rhythm disturbances, severe skin reactions, acute myocardial infarction, seizures, diabetes, psychosis and aggression.
Following this, FDA issued a Public Health Advisory about one of the most marked adverse effects of varenicline, psychiatric symptoms that included “changes in behavior, agitation, suicidal ideation, attempted and completed suicide.”
From May 2006 through December 2007, the FDA had received 227 domestic reports of suicidal acts, thoughts or behaviors, 397 cases of possible psychosis and 525 reports of hostility or aggression. These totals included 28 cases of suicide and 41 mentions of homicidal ideation, 60 cases of paranoia and 55 cases of hallucination. The categories were not mutually exclusive.
In the 4th quarter of 2007 varenicline accounted for 988 serious injuries in the U.S. reported to the FDA, more than any other individual drug in this time period.
While launching Champix in India, Pfizer said that the company had worked with the FDA to incorporate these concerns in the labelling.
Smokers usually show higher inclination to psychiatric illnesses, he said. The suicide incidents came up in the post-marketing survey and not during the clinical trials.
GlaxoSmithKline’s Zyban (buproprion) too, had been linked to adverse reactions. Similar concerns are addressed on Champix’s product insert in Europe, as well.
Pfizer, however, is confident on the benefits of the drug. Champix would carry, in India too, will carry information on the psychiatric concerns on its product insert, similar to the product in Europe.
Champix was developed specifically to act on reducing nicotine craving and the pleasure of smoking. Research showed that the odds of quitting smoking on Champix are twice that of buproprion and four times that of placebo. Though no revenue projections were made on the drug, the product is being rolled out across 17 cities in the country, Pfizer had said.
According to Pfizer, India has a tobacco-related disease burden of over Rs 24,000 crore, and by 2010 it is estimated that over one million Indians will die of smoking-related diseases.
However, it is not necessary that Dr Reddy’s post-grant opposition against Champix should be granted by the Indian Patent Office. Recently, a similar post-grant opposition filed against Roche’s Pegasys – a pegylated interferon –by Wockhardt and some NGOs was rejected by IPO.