PUREPAC IS SECOND ENTRANT IN GENERIC NIFEDIPINE MARKET

PUREPAC IS SECOND ENTRANT IN GENERIC NIFEDIPINE MARKET with the Sept. 13 launch of a 20 mg gelcap formulation of Pfizer's Procardia. KaliPharma's Purepac subsidiary announced Sept. 13 that it "has commenced marketing" its generic nifedipine product, with pricing set at a 30% discount to the brandname product. Purepac's average wholesale price (AWP) is $71 per bottle of 100 and$208.80 per bottle of 300.

The launch follows by seven days Chase Labs' introduction of the first generic nifedipine, a 10 mg gelatin capsule, also at a 30% discount to Procardia ("The Pink Sheet" Sept. 10, p. 7). Chase estimated at the time of the launch that the 10 mg dosage strength generated about half of the total nifedipine market, which it put at $500 mil. Purepac estimates that the nifedipine market "exceeds $300 mil." and that it will command a "significant share" of the generic market.

The introduction of the KaliPharma product appears to mark the first time that a generic version of a drug still on-patent has been available simultaneously in more than one dosage level and raises questions about the limits of exclusivity. Chase also has a pending ANDA for a 20 mg strength.

Like Chase, Purepac reached a consent agreement with Pfizer after challenging the Pfizer patent that enables the generic firm to introduce a generic nifedipine while the brandname is still on-patent. The patent expires on Jan. 8, 1991. However, unlike Chase, which received 180 days of exclusivity from FDA for its 10 mg generic nifedipine product when its ANDA was prospectively approved in July 1989 ("The Pink Sheet" July 24, 1989, T&G-7), Purepac's 20 mg product will not receive an FDA grant of exclusivity.

KaliPharma said it delayed introduction of its generic nifedipine 20 mg due to provisions of the company's consent agreement with Pfizer. Under one "trigger point" in the Pfizer-KaliPharma consent order, which followed the signing of a sub-licensing agreement, KaliPharma said it agreed to postpone the launch of its nifedipine product until Chase introduced its product.

On April 28, 1989, Purepac parent KaliPharma became the first company to receive prospective approval to market both 10 mg and 20 mg generic nifedipines ("The Pink Sheet" May 8, 1989, T&G-16). However, the effective approval dates of the KaliPharma products were delayed until not earlier than 180 days after either FDA received notice from Chase of the first commercial marketing of the product or the date of a court decision in the Pfizer/Chase patent infringement suit.

Although Chase was the first to file an ANDA for nifedipine, the firm received a prospective approval of its 10 mg dosage strength on July 10, 1989 -- two-and-a-half months after KaliPharma. The approval was delayed until July 4, 1990, 30 months after Pfizer sued Chase for patent infringement in response to Chase's filing a patent challenge and ANDA in December 1987. However, as the July deadline approached this year, Chase agreed to hold off marketing its generic nifedipine until the judge in the patent case officially signed the consent order between Pfizer and Chase. The consent decree was issued Sept. 4, which leaves Chase with essentially four months of exclusivity for its 10 mg strength of nifedipine until Pfizer's patent expires in January.

A separate issue linking Chase and Purepac is a lawsuit filed in June in D.C. federal court by KaliPharma against FDA challenging Chase's market exclusivity for nifedipine. The suit alleges that Chase's ANDA was not "substantially complete" ("The Pink Sheet" June 25, T&G-6) when it was filed and seeks a judgment revoking Chase's exclusivity period. The lawsuit deals solely with Chase's 10 mg product and is still being pursued by KaliPharma, which is, pending a decision, barred from launching a 10 mg product until Procardia's patent expires.

Another barrier to KaliPharma's launching of a 10 mg product is FDA's recision of the firm's 10 mg ANDA because of analytical work done on the application by Biodecision Labs. Chase's ANDA was also rescinded for the same reason, but the company sued FDA in Newark federal court arguing that the agency had no authority to rescind an already approved ANDA. The court granted Chase preliminary relief on Sept. 4 and awarded an injunction reinstating the ANDA. KaliPharma said it has reviewed the work done by Biodecision Labs and sent a response to FDA.