Pfizer Seeks to Counter Chantix Concerns

-CBS News

05/29/2008- Pfizer Inc. is preparing an advertising and public-relations campaign to counter concerns about its antismoking drug Chantix, once trumpeted as a potential billion-dollar-a-year blockbuster.

Chantix is drawing scrutiny from federal regulators and a tough congressional critic of the pharmaceutical industry following revelations about potentially dangerous adverse events such as heart irregularities, seizures and more than 100 accidents linked to use of the drug.

An important issue is whether Chantix is effective at dosage levels that are safe for its users. This was a concern for FDA researchers prior to the drug's approval, according to agency records.

The FDA's own review prior to its approval of Chantix in 2006 suggested that higher dosages of Chantix appeared more effective in helping users to stop smoking, but also showed a greater incidence of potentially harmful side effects.

Pfizer's researchers said that the FDA raised concerns about the dose size with the company as part of the normal approval process, but noted that the FDA ultimately approved the drug for the dose recommended in trials that showed Chantix better at stopping smoking than its competitor drug or a placebo.

Pfizer had counted on Chantix, which neared the $1 billion blockbuster mark with $883 million in sales last year, to help it make up some of the $13 billion in revenue it stands to lose when cholesterol fighter Lipitor faces generic competition. In the wake of questions about the drug's safety, Pfizer plans Thursday to run ads in five major newspapers in which its medical director explains Chantix's risk-benefit balance. Next week, the company will start hosting round-table discussions on Chantix for members of the media.

The campaign comes as Sen. Charles Grassley of Iowa, ranking Republican on the Finance Committee, has asked the FDA about a study released May 22 by an outside research group -- the Institute for Safe Medication Practices -- that linked Chantix to 988 serious side effects in the last quarter of 2007. He wrote that he was "troubled to read that during the fourth quarter of 2007, Chantix accounted for more reports of serious adverse events in this country than any other prescription drug."

"The report states that the FDA never warned consumers about other kinds of serious harm caused by Chantix," his letter said. Pfizer says most, if not all, of the newly reported side effects are in the drug's existing product label, and feels that label accurately reflects the drug's risk-benefit balance and includes information about adjusting the dose.

The FDA upgraded the warnings on Chantix this year to include neuropsychiatric issues such as depression and suicidal thinking. But the recent ISMP study raised alarms about the many non-neuropsychiatric side effects previously reported to the FDA that the agency didn't flag in warnings to consumers. ISMP is a nonprofit group based in the Philadelphia suburbs. The ISMP study analyzed the FDA's own publicly available adverse-events data collected since the drug came to market.

Chantix was given priority review status because of the many deaths linked to smoking. It wasn't put before an FDA advisory committee for a public debate and vote before it was approved for market. In May 2006, an FDA reviewer noted "tolerability issues" at the dose of 1 milligram twice a day; problems included nausea, attention disruption, chest pain, drowsiness, depression and abnormal dreams.

The FDA reviewer wrote that Pfizer's final report revealed "many drug-related adverse events showing a dose-dependency" and suggested patients had fewer side effects and stayed on the drug longer when they were allowed to lower the dosage to half the recommended dose.