In the wake of a recall in Europe of Roche’s Viracept last month, after certain batches were found to have been contaminated with excess levels of a potential human carcinogen, Pfizer, which sells the antiretroviral in the USA, has issued a warning about the HIV drug.

Pfizer has issued a letter to inform healthcare professionals of the presence of ethyl methanesulfonate, “a process-related impurity” in Viracept (nefinavir) and to provide guidance on the use of the drug in pregnant women and children. Data from animal studies indicate EMS is teratogenic, mutagenic and carcinogenic and although no data from humans exist, the US Food and Drug Administration has asked the New York-based firm to “implement new specifications to limit the presence of EMS in Pfizer-manufactured Viracept”.

Specifically, the letter says that for paediatric patients who are stable on Viracept, the FDA and Pfizer agree that the benefit-risk ratio remains favourable and they may continue to receive the drug. However, those children who need to begin HIV treatment should not start regimens containing Viracept until further notice. The latter goes for pregnant women and, as a precautionary measure, those currently receiving Viracept should be switched to an alternative antiretroviral therapy for the timebeing, if possible.

Pfizer CEO predicts dip in Lipitor sales

Staying with Pfizer and the firm’s chief executive Jeffrey Kindler has reportedly predicted a sales decline this year for the blockbuster lipid lowerer Lipitor (atorvastatin). He was speaking at the Bear Stearns Healthcare Conference in New York for investors, an event closed to the press, but Bloomberg reports Mr Kindler as saying that “we see Lipitor sales coming in for the year within the range we previously forecast, although trending toward the lower end of the range”. In July, Pfizer said that Lipitor sales would either be stable this year at $12.9 billion or drop 5%.

One of the main reasons cited by the CEO for the decline was “an intense effort by managed care, unprecedented in our industry,'' to give incentives to patients to use generics. In the case of cholesterol drugs, patients have been switching in their droves to generic copies of Merck & Co’s Zocor (simvastatin), which acts in a similar way to Lipitor.

Mr Kindler also said that the company expects to "generate four new products a year starting in 2011" and claimed the $20 billion estimate that analysts have put on the revenues Pfizer will lose to generic competition by 2011 “overstates the size of the challenge''. Bloomberg also reports him as saying that sales of the drugs going off patent are not ”going to go to zero”.