FDA and Pfizer Set Specifications Allowing Nelfinavir (Viracept) To Again Be Prescribed for Children and Pregnant Women

In September 2007, Pfizer issued a letter to healthcare providers providing new guidance on the use of nelfinavir (Viracept) in HIV positive children and pregnant women, after excess levels of ethyl methane sulfonate (EMS) were detected in nelfinavir manufactured by Roche and marketed outside the U.S.

EMS is a manufacturing impurity that can cause birth defects and may potentially increase the risk of cancer, especially in children. Although high levels of EMS were not detected in nelfinavir produced and sold by Pfizer in the U.S., the Food and Drug Administration (FDA) asked the company to limit levels of EMS in its product. Pfizer and the FDA advised that children and pregnant women should not start nelfinavir, though children could remain on the drug if they were already taking it.

In March of this year, the FDA and Pfizer agreed on a limit for EMS in nelfinavir, leading to the lifting of the recommendation against its use by children and pregnant women. Nelfinavir may now once again be prescribed for all HIV patients.

Below is an excerpt from Pfizer's recent letter to healthcare providers announcing the agreement:

Viracpet (nelfinavir mesylate) 250 mg, 625 mg tablets, and Powder for Oral Suspension

IMPORTANT INFORMATION FOR PRESCRIBERS

May 6, 2008

Dear Healthcare Professional:

The purpose of this letter is to inform you that Pfizer and FDA have agreed on a final limit for ethyl methane sulfonate (EMS) in nelfinavir mesylate (active ingredient in Viracept) and to provide guidance on the use of Viracept in patients.

On Sept 10, 2007, Pfizer informed prescribers of the presence of EMS, a process-related impurity in nelfinavir mesylate (active ingredient in Viracept) and provided guidance on the use of Viracept in pregnant female and pediatric patients. At that time, FDA asked Pfizer to implement an interim specification to limit the presence of EMS in nelfinavir mesylate used in Pfizer's Viracept products marketed in the United States, while continuing to work towards a long-term specification. Healthcare providers were advised not to initiate antiretroviral regimens containing Viracept in their pregnant female and pediatric patients. In addition, pregnant females who were receiving Viracept were to be switched to alternative anti-retroviral therapy unless no alternative therapy was available to them. For pediatric patients who were stable on Viracept -containing regimens, the FDA and Pfizer agreed that the benefit-risk ratio remained favorable and those patients could continue to receive Viracept. There was no change in the recommended use of Viracept for all other patients.

Effective March 31, 2008, all Viracept manufactured and released by Pfizer meets the new final limits established by the FDA for prescribing to all patient populations, including pregnant female and pediatric patients.

[For full prescribing information, see www.viracept.com].

Sincerely,

William A. Erhardt, MD
Vice President Specialty Medical [Pfizer]

5/23/08

Source
Pfizer. Viracept (nelfinavir mesylate) 250 mg, 625 mg tablets, and Powder for Oral Suspension. Letter to healthcare professionals. May 6, 2008.