Court Denies Validity of AstraZeneca's Toprol-XL Patent

On Monday, the Federal Circuit affirmed(pdf) a district court summary judgment decision that AstraZeneca's (AZN) U.S. Patent No. 5,081,154 is invalid for double patenting. The '154 patent claims metoprolol succinate, the active ingredient in Astra's blockbuster cardiovascular drug Toprol-XL. KV Pharmaceutical, Andrx, and Eon Labs have all filed ANDAs for generic Toprol-XL and are defendants in the litigation.

The Federal Circuit explained that "non-statutory, or 'obviousness-type,' double patenting is a judicially created doctrine adopted to prevent claims in separate applications or patents that do not recite the 'same' invention, but nonetheless claim inventions so alike that granting both exclusive rights would effectively extend the life of patent protection." The majority (Judges Gajarsa and Mayer) concluded that the '154 patent is invalid for double patenting over U.S. Patent No. 4,780,318. The '318 patent expired in 2005 and claims pharmaceutical compositions containing one of a number of active ingredients (including metoprolol succinate), while the '154 patent has not yet expired and, as noted, claims the compound metoprolol succinate. Judge Schall dissented.

According to the majority opinion, a 1997 Federal Circuit decision, In re Emert, 124 F.3d 1458, mandated the invalidity finding in this case:

In Emert, this court held the claims of an application unpatentable for double patenting, finding that "the '887 application's claimed invention, an oil soluble dispersant comprising B1, while not anticipated by the '624 patent due to the slight modification of three claim limitations, would have been prima facie obvious in light of the claim to the combination [A and B]" because the patentee "effectively conceded that the differences between B and B1 are not material and would have been obvious to a person having ordinary skill in the art." Similarly, in this case, Claim 1 of the '154 Patent claiming a compound (A1) is an obvious variation of Claim 8 of the '318 Patent claiming a composition comprised of one compound of an enumerated list (A1, A2, A3, etc.), an inner layer (B), and an outer layer (C). Specifically, it would have been an obvious variation of Claim 8 of the '318 Patent to omit the inner layer (B) and the outer layer (C). Astra offers no convincing reason why Emert does not apply.

In dissent, Judge Schall disagreed that Emert controls this case. According to Judge Schall, "the critical point is that, in this case, the compound metoprolol succinate has not been claimed twice." He explained: "I believe the law is that there is no double patenting simply because a later claimed element is set forth in an earlier claim to a combination."

Besides affirming the invalidity finding, the Federal Circuit also vacated the district court's summary judgment decision of inequitable conduct, and remanded the case for resolution of a factual dispute over whether Astra had the requisite intent to deceive the patent office during prosecution of the '154 patent. The Federal Circuit explained that it reached this issue "because the parties dispute whether a patentee may reinstate the validity of a patent by filing a terminal disclaimer during litigation," and the Federal Circuit has not yet decided that question.

RELATED READING:

Sandoz press release

10/29/06 OBB post, reporting on KV Pharma's Toprol-XL citizen petition