Many new drugs initially enjoy banner sales growth, only to get kneecapped by reports of previously unknown adverse side effects. On Friday, the FDA issued an alert "highlighting" a stricter warning label for one of Pfizer's
The compound in question, Chantix, is one of the most recent non-nicotine stop-smoking treatments on the market. The FDA approved it back in 2006, but after its launch, some of the more than 5 million patients who have tried the drug began to report adverse events, including anxiety, other serious psychiatric changes, and "vivid" and "unusual" dreams. As a result of these reports, Pfizer strengthened the warning label for Chantix. Last week's FDA announcement formalized more specific safety warnings for the drug's label.
As with GlaxoSmithKline's
Chantix is Pfizer's most important new drug right now. Sales of the drug have grown much faster than I expected, up a very strong 312% year over year in the fourth quarter, to $280 million worldwide. Besides Chantix, and a revenue boost from pain drug Lyrica after its fibromyalgia label expansion last June, Pfizer has few other new growth opportunities on the market or in its late-stage drug pipeline.
Fortunately for investors, the 2008 guidance Pfizer issued two weeks ago already accounted for the effects of this labeling revision (and a similar one pending in the European Union) on this year's revenue. Still, if Chantix's excellent sales trajectory stalls, the tough situation Pfizer faces in coming years will only get more difficult.