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Process-Related Impurity (ethyl methanesulfonate - EMS) in all strengths and formulations of VIRACEPT (nelfinavir mesylate)


September 10, 2007 – The U.S Food and Drug Administration (FDA), and Health Canada the equivalents of the Saudi Food and Drug Authority (SFDA), announced that Pfizer issued a Dear Healthcare Professional Letter to inform healthcare professionals of the presence of ethyl methanesulfonate (EMS), a process-related impurity in VIRACEPT (nelfinavir mesylate) and to provide guidance on the use of VIRACEPT in patients, including pregnant women and pediatric patients. Viracept used for HIV patient.

EMS is a potential human carcinogen (Class 2B). Data from animal studies indicate EMS is teratogenic, mutagenic and carcinogenic; however, no data from humans exist.

In June, 2007 Roche recalled Veracipt from all European Union (EU) market due to detection of excess level of EMS in Veracipt Product.

In response to the Roche recall, FDA, Health Canada and Pfizer agreed to limit EMS in Veracipt Product. Only product meeting the interim specifications will be released for patients use.

Actions that Public and Healthcare professionals should follow:

At this time, physicians should consider the risks and benefits of prescribing VIRACEPT to their HIV-infected adult patients, given the information provided below. In general, it is recommended that HIV-infected patients should be switched from VIRACEPT to an alternative therapy if this can be done safely.

  • Patients should NOT stop taking VIRACEPT without first consulting with their physician.
  • The following groups of patients may be more susceptible to harm from EMS :
  • Pregnant women
  • Children
  • VIRACEPT should NOT be used for post-exposure prophylaxis (occupational or non-occupational).
  • VIRACEPT should NOT be prescribed for adults and children needing to initiate therapy.
  • Pharmacists should notify the treating HIV physician when patients present for renewal of VIRACEPT prescriptions.

Managements of Pediatric Patients: pediatric patients who are stable on Viracept-containing regimens, FDA, Health Canada and Pfizer agree that the benefit-risk ratio remains favorable and those patients may continue to receive Viracept. Pediatric patients who need to begin HIV treatment should not start regimens containing Viracept until further notice.

Managements of Pregnant women: Pregnant women who need to begin antiretroviral therapy should not be offered regimens containing Viracept until further notice. As a precautionary measure, pregnant women currently receiving Viracept should be switched to an alternative antiretroviral therapy while Pfizer and FDA and Health Canada work to implement the long term EMS specification for Viracept. For pregnant women with no alternative treatment options, FDA, Health Canada and Pfizer agree that the risk-benefit ratio remains favorable for the continued use of Viracept.

Report Adverse Drug Reactions to the Saudi FDA

The public and health professionals are encouraged to report adverse drug reactions of Veracipt to the National Pharmacovigilance center on the internet at: