Pfizer Calls On FDA to Replace Method for Assessing Conjugated Estrogen Products

Sponsors of generics for Pfizer’s estrogen drug Premarin should use the “Pfizer method” for assessing sameness rather than the method recommended in FDA draft guidance, the company said in a citizen petition.

The FDA’s December 2014 draft guidance for establishing sameness is “fundamentally flawed,” Pfizer writes in the petition. Not only does it lack a critical level of sensitivity on API steroidal composition, according to the drugmaker, it does not account for all classes of components in the API or the non-steroidal components.

Future guidance should instead use the “Pfizer Method” that the company developed at the agency’s request and with the FDA’s input, which permits a determination of sameness between a proposed generic for the company’s drug Premarin and the reference drug based upon the mixture as a whole, while allowing a comparison across all categories of components making up the API.