EMS in Viracept--the course of events in 2007 and 2008 from the non-clinical safety point of view.

Viracept (nelfinavir) is an HIV protease inhibitor supplied by Roche outside the US, Canada and Japan. Viracept was first introduced by Roche in 1998. Although newer protease inhibitors have become available for the treatment of HIV, it is viewed as a useful medicine for patients who are intolerant to ritonavir (since it does not require ritonavir boosting), pregnant women, and patients in resource-limited settings, since the formulation is heat-stable and does not require refrigeration. The relatively high prevalence of HIV in some of the third world countries means that it was also a product of choice for young women of childbearing age, pregnant and nursing women and young children. On 18 May 2007 F. Hoffmann-La Roche received first reports of a "bad smell" of blisterpacked Viracept tablets and one adverse drug report of nausea and vomiting from patients in Spain. Subsequently, ethyl methanesulfonate (EMS), an established mutagen, carcinogen and teratogen was identified as the potential source of the bad smell. On 6 June 2007, Viracept was globally recalled as the extent of the contamination exceeded the guidances for permissible levels set by regulatory authorities by more than 1000-fold and hence human risk was not readily assessable. In the following, a compilation of the course of events from a non-clinical point of view is presented. This compilation only partially reflects the complexity of the case and the interactions between all parties between May/June 2007 and September 2008 and hence necessarily remains partly a subjective compilation of the authors of this article. This compilation serves also as an introduction into this Special Issue of Toxicology Letters. The data on the cause and levels of contamination, likely duration of intake and affected patient population can be found in the subsequent contributions. Most importantly, we share in other parts of this Special Issue with the scientific community the data and risk assessment arguments that supported the conclusion by the company and regulatory authorities that the levels of contamination with EMS posed no health risk to affected patients.