CHASE’s GENERIC NIFEDIPINE MARKET EXCLUSIVITY CHALLENGED BY KALIPHARMA

CHASE's GENERIC NIFEDIPINE MARKET EXCLUSIVITY CHALLENGED BY KALIPHARMA in a suit against FDA filed in D.C. federal court on May 29. In its complaint, Kalipharma seeks a court judgement revoking the six-month exclusivity granted to Chase for generic nifedipine (Pfizer's Procardia) 10 mg capsules and requests a court order requiring FDA to issue to Kalipharma an amended approval letter with "an appropriate new effective date for approval" of its own generic nifedipine. FDA has 60 days to respond to Kalipharma's complaint. The suit claims that Chase is not entitled to 180-day exclusivity because Chase's ANDA was not "substantially complete" at the time of its initial submission to FDA in December 1987 and, therefore, should not be counted ahead of Kalipharma's March 25, 1988 application. FDA approved Chase's ANDA July 10, 1989 ("The Pink Sheet" July 24, 1989, T&G-7). The approval is effective July 4, 1990 or at a time determined by the New Jersey federal court that heard a Pfizer infringement claim against Chase. The suit is still pending. "The action of FDA in finding that Chase submitted a 'substantially complete' ANDA for the product prior to Kalipharma was...erroneous and unwarranted by the facts," the complaint argues, "and upon information and belief, was the result of oversight or mistake by the person who reviewed Chase's ANDA at the time of filing." Kalipharma's ANDA for the product was approved on April 28, 1989 with an effective date delayed until not earlier than 180 days after either: (a) FDA receives notice from Chase of the first commercial marketing of the product under the previous ANDA; or (b) the date of a court decision in the suit against Chase holding the [Procardia] "684" patent invalid or not infringed. The patent is due to expire Jan. 1, 1991. Pfizer's patent infringement action against Kalipharma's ANDA for the product was settled by the entry of a final judgement "on consent" on Jan. 5, 1990, following the execution of a patent sublicense agreement between Pfizer and Kalipharma dated Jan. 4, 1990, according to the suit. Kalipharma contends that Chase's initial ANDA was not substantially complete because the bioequivalence study included in the application was deficient "for reasons that should have been apparent on its face at the time of filing." The bioequivalence study showed: (1) the 90% confidence interval ratio for the Chase product's Cmax to that of Procardia was "far outside the plus or minus 20% range acceptable under current FDA review procedures"; and (2) that Chase submitted two sets of data analysis for its human test subjects, but had omitted data for five test subjects in the second analysis because they 'exhibited anomalous behavior after administration with the reference'," Kalipharma stated. The complaint alleges that "the fact that Chase submitted a second set of analysis data for its human test subjects...also shows that Chase was attempting, albeit unsuccessfully, to overcome the deficiencies of the data that resulted from the complete test analysis for all subjects." Such activity "should have 'rung a bell' as soon as FDA reviewed the Chase ANDA." The complaint also notes that Chase submitted a second study on Oct. 11, 1988, that was found unacceptable by FDA on Feb. 19, 1989.