'Quit smoking' blow for Pfizer

Pilots and air traffic controllers in the US have been banned from taking Pfizer's stop-smoking pill Chantix on fears about side-effects.

It has been linked to more than 3000 reports of problems including suicides, heart trouble and aggression, according to a new study by the non-profit Institute for Safe Medication Practices that sparked the Federal Aviation Administration review.

The FAA had approved the use of Chantix for pilots and flight controllers last year. It has been prescribed 3.5 million times in the US since it was approved in 2006.

It is a blow to Pfizer but potentially good news for GlaxoSmithKline, which markets another quit-smoking aid in the drug bupropion - sold worldwide under the brand names Wellbutrin and Zyban.

However, Glaxo has its own problems with Wellbutrin, one of the drugs worst-hit by generic competition. Sales were down 3% at £126 million the firm reported last month.

Pfizer said the labelling for Chantix reflected the product's safety profile, and added that benefits outweighed risks.