A decision on the relevance of AstraZeneca's antibiotic-related patents for the proton pump inhibitor Prilosec (omeprazole) is expected by August.

Three patents at issue in consolidated patent litigation pending in Manhattan involve antibiotic-related claims for Prilosec. Two (Nos. 5,599,794 and 5,629,305) cover the use of omeprazole in combination with antibiotics for treatment of H. pylori-induced ulcers.

The third patent (No. 5,093,342) covers use of omeprazole itself as an antibiotic agent for treatment of Campylobacter infections. The three patents expire in 2010 and 2014.

Assuming the generic manufacturers are successful in their summary judgment motions related to the three patents, the litigation would be reduced to arguments over the basic omeprazole patent (which expires in October) and two delayed-release formulation patents.

The Manhattan case includes four generic defendants: Andrx, Genpharm, Schwarz Pharma and Cheminor. Under a Jan. 2 memorandum of understanding with Genpharm, Andrx will market generic omeprazole under either its own or Genpharm's ANDA depending on which one can be marketed first (¹ Also see "Prilosec Case Could Go To Trial After Decision On Inclusion Of Process Patent" - Pink Sheet, 8 January, 2001.).

A May 29 summary judgement from Judge Barbara Jones rejected AstraZeneca's claim that Genpharm and Cheminor infringe a patent for active metabolites of omeprazole called sulphenamides (No. 4,636,499). The patent expires in 2006.

AstraZeneca argued that the generics would violate the '499 patent because they would convert to the patented drug in the body.

Genpharm and Cheminor argued "that the inventors of the '499 patent intended to claim only synthetically produced sulphenamides," Jones' decision notes.

AstraZeneca believed the patent covered "both sulphenamides made synthetically outside the body as well as those produced by the in vivo conversion of omeprazole."

The company conceded "that if the '499 patent is construed to claim only synthetic sulphenamides, the defendants' products will not infringe it.

The decision states that "the language of the claims at issue supports defendants' contentions that the inventors of the '499 patent intended to claim synthetic sulphenamides only."

AstraZeneca argued "that the '499 patent specification language expressly discloses...that the claimed sulphenamides may be formed in the body and that the specification describes the in vivo conversion of omeprazole to sulphenamides," the ruling notes.

Genpharm and Cheminor countered that the in vivo formation of sulphenamides was disclosed in the basic compound patent on Prilosec (4,255,431) and "in numerous prior art references published more than a year before [AstraZeneca's] application for the '499 patent," the decision states.

"By claiming patent protection for sulphenamides formed in vivo after the oral administration of omeprazole, [AstraZeneca] has merely attempted to patent the unpatentable," the judge ruled.

"Had [AstraZeneca] demonstrated that the mechanism of omeprazole and sulphenamides in vivo had changed since the publication of the prior art sources," the decision states, "it would have been relevant to the anticipation analysis because it would have created a factual issue with respect to what occurred in the prior art."

Patent '431 expires Oct. 5, following a six-month pediatric exclusivity extension. On May 2, Judge Jones denied a summary judgement motion filed by Cheminor that the '431 patent be ruled invalid.

With the exclusion of the patent covering sulphenamides, AstraZeneca has two additional patents at issue in the case, covering the delayed-release formulation of omeprazole (Nos. 4,786,505 and 4,853,230). Both patents expire in 2007.

Andrx expects the case to be decided as early as the end of the year.

AstraZeneca has not filed patent infringement litigation on four process patents submitted to FDA in March. The patents run as late as 2019 (² Also see "AstraZeneca Awaits "Orange Book" Listing For Three Prilosec Patents" - Pink Sheet, 19 March, 2001.).

AstraZeneca Loses One Prilosec Patent: Three Others To Be Decided By Aug.

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