NEW YORK CITY (dpa-AFX) - Pfizer Inc. (PFE), the world's biggest drugmaker, said Monday that the reliable science on varenicline, or Chantix/Champix, involving more than 14 clinical trials with more than 7,000 smokers, and the medicine's approval by regulatory authorities around the world, show the importance of the medicine as an effective and appropriate treatment option for adult smokers wanting to quit.
The company said it stands behind the benefit/risk profile of Chantix.
The company expressed concerns about the reliability of the meta-analysis by Singh et al published today in the Canadian Medical Association Journal. Those concerns, among others, are related to the appropriateness of the authors' measure of cardiovascular risk, or composite endpoint, which combines events that do not share a common biological cause; the manner in which cardiovascular events were counted and classified; and a small number of events, which forms the authors' conclusions.
The authors themselves acknowledge that the cardiovascular risk 'estimates are imprecise owing to the low event rates,' the company noted.
Pfizer said it is discussing with the U.S. Food and Drug Administration a protocol to conduct a meta-analysis of its clinical trial data to help further evaluate the cardiovascular safety of Chantix.
The company said the meta-analysis will address a number of limitations in the Singh analysis. Pfizer expects that it will be based on a more reliable composite endpoint to measure cardiovascular risk, as well as a validated process to classify, or adjudicate, cardiovascular events that are part of the composite endpoint.
Chantix was approved by the FDA in May 2006 as an aid to smoking cessation treatment in adults 18 and older. Chantix is currently approved for use in 99 countries around the world.
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