ViroPharma has pulled out all stops to prevent generic copies of its off-patent Vancocin® capsule (vancomycin hydrochloride) including the use of the Citizen Petition process. Recently, FDA denied most of the requests in their Citizen Petition and simultaneously approved generics from 3 companies. ViroPharma immediately responded by filing a suit against the FDA.

A reading of the FDA CP Response provides a lot to learn about – waivers, BCS, in vitro and in vivo requirements, non-systemically absorbed drugs and how FDA works with Advisory Committees. While these issues are targeted at generics, some spill over into 505(b)(2). This blog post will focus on ViroPharma’s request for 3-year exclusivity and FDA’s denial.

Clearly, ViroPharma was trying many angles to prevent generic competition to its main revenue-generating product, Vancocin. Last December, ViroPhara received approval for a labeling change. ViroPharma asserted that the labeling changes were based on 2 clinical studies (505(b)(2) alert: ViroPharma licensed the study results from the vancomycin comparator arm of 2 failed Genzyme studies examining a candidate replacement of vancomycin – a great source of information). Indeed, the FDA website suggests the changes were based on clinical data:

Apparently the FDA did not grant the 3-year exclusivity afforded to changes based on clinical evidence (see 505(j)(5)(F) generally and for NDA supplements see (iv)). Therefore ViroPharma added this issue to the Citizen Petition. On pages 66-73 of the Citizen Petition Response the FDA sets forth the reasons why this product, an “old antibiotic”, cannot be granted exclusivity; 505(v)(3)(B) prevails – “old antibiotics” are not subject to exclusivity unless there is a new condition of use, which the FDA determined was not present in the revised labeling.

Prior to the 1997 FDAMA legislation, antibiotics were regulated under FD&C section 507; antibiotics were not subject to the 1984 Hatch-Waxman Amendment provisions of exclusivity and patents. FDAMA (section 125) repealed section 507 and placed antibiotics under section 505 and specified that antibiotics submitted before November 21, 1997 (“old antibiotics”) were exempt from the provisions of patent listing, patent certification, and market exclusivity. In 2008, this restriction on old antibiotics was lifted with the passage of the QI Program Supplemental Funding Act of 2008 (QI Act). However, this 3-year exclusivity is not available for “any condition of use for which the [old antibiotic].. was approved before the date of the enactment of the QI Act” (505(v)(3)(B). FDA decided that Vancocin’s revised label did not contain a new condition of use and thus not eligible for any exclusivity. Since “new condition of use” was not defined in the QI Act, it is entirely possible that ViroPharma will fight the FDA on this basis.