Addressing a number of issues in a Hatch-Waxman litigation over the generic versions of the drug Prilosec, the U.S. Court of Appeals for the Federal Circuit upheld a district court's rulings of infringement and validity. In re Omeprazole Patent Litigation (AstraZeneca AB v. Apotex Corp. and Impax Labs., Inc.), Case Nos. 07-1414, -1416, -1458, ‑1459 (Fed. Cir., Aug. 20, 2008) (Bryson, J.).
The two patents at issue relate to drug preparations containing omeprazole, the active ingredient in Prilosec, a gastric acid inhibitor. The patents claim an outside enteric coating over an inert subcoating for a drug tablet or capsule that increase stability of the drug while on the shelf and protect the active ingredient from degradation due to gastric acid in the stomach, so that the active ingredient can be released in the small intestine. The patents expired on April 20, 2007, but the Food and Drug Administration (FDA) granted AstraZeneca a six-month exclusivity extension due to pediatric testing. On May 31, 2007, the district court found that Apotex and Impax Labs each infringed the two patents at issue and that the patents were not invalid due to anticipation, the public-use bar or obviousness.
On appeal, both parties argued that the district court lost jurisdiction over the case after the at issue patents expired on April 20, 2007. They further argued that AstraZeneca's claim of infringement became moot. In finding jurisdiction, the Federal Circuit relied on 35 U.S.C. § 271(e)(4)(A), which requires the district court, after a finding of infringement, to set the effective date for approval of a generic version to the expiration date of the patent and 21 U.S.C. § 355a(b)-(c), which extends the period of FDA approval of a generic version to six months after the patent expires in the case of pediatric testing. Based on these statutes, the Court found that the plaintiff's claim was still justiciable since there was still time left in the plaintiff's exclusivity period.
Impax argued that the patents were invalid under the public use bar of 35 U.S.C. § 102(b). Before the critical date (one year prior to filing the patents), AstraZeneca commissioned large clinical studies to determine the safety and efficacy of the drug formulation in order to gain FDA approval. The district court did not find the patents invalid because the studies were experimental uses, and therefore not public uses, and the patented formulation was not ready for patenting until after the studies were completed. The district court had found that even if the patented formulation had been reduced to practice before or during the clinical studies, the experimental use exception negated the public-use bar.
The Federal Circuit found that the district court misapplied the experimental use exception—once an invention is reduced to practice, it cannot be the subject of an experimental use exception. That ruling was not fatal to the patent in this case, however, because the district court found as a factual matter that the claimed formulation was not ready for patenting until after the studies were completed. The Court found that because there were still stability problems during testing, the formulation was changed during the different phases of clinical studies and the formulation that was patented was the one that was tested during the last phase (Phase III). Readiness for patenting can be shown by reduction to practice before the critical date and reduction to practice requires both constructing an embodiment or performing a process meeting all the limitations and determining that the invention works for its intended purpose. Impax did not demonstrate that without conducting the Phase III trials the inventors knew that the Phase III formulation would achieve the claimed stability. Since Impax did not produce evidence that the inventors determined before the studies were completed that the invention would work for its intended purpose, there was no error in the district court's finding of no reduction to practice or readiness for patenting prior to the critical date.
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