Pfizer issues guidance on process impurity in Viracept
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Pfizer issues guidance on process impurity in Viracept Pfizer has issued a ’Dear Healthcare Professional’ letter regarding the presence of a process-related impurity, ethyl methanesulfonate (EMS), in nelfinavir [Viracept] 250mg and 625mg tablets and in nelfinavir powder for oral suspension. The letter was prompted by detection of excess levels of EMS (a potential carcinogen) in Roche-manufactured nelfinavir in June 2007; Roche recalled Viracept from all EU markets. In response, the US FDA and Pfizer have agreed new limits for EMS in Pfizer-manufactured nelfinavir marketed in the US. Testing showed that the levels of EMS were substantially lower than those that led to the Roche recall. Interim specifications limit the theoretical lifetime increased cancer risk in adults to < 17 cases per 100 000 exposed while the long-term specifications limit the theoretical lifetime risk to < 1 case per 100 000 exposed. At this point, Pfizer advises that paediatric patients and pregnant women starting HIV therapy should not receive regimens containing Viracept. The FDA and Pfizer determined that the benefit-risk ratio remains favourable for paediatric patients who are stable on Viracept-based regimens and that they should continue to receive Viracept. Pregnant woman should be switched from Viracept to an alternative antiretroviral therapy while progress is made towards the long-term EMS specification. However, for those women with no alternative therapy options, the FDA and Pfizer agree that the risk-benefit ratio for continuing Viracept remains favourable. Pfizer Inc. VIRACEPT (Rm) (nelfinavir mesylate) 250 mg, 625 mg tablets, and powder for oral suspension. Internet Document : [3 pages], 10 Sep 2007. Available 801052292 from: URL: http://www.fda.gov
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Reactions 22 Sep 2007 No. 1170
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