AstraZeneca’s patent on Toprol-XL® was found invalid after the CAFC affirmed a district court’s invalidity holding based on double patenting but vacated the district court’s inequitable conduct holding and remanded the case to see if the patent and another one should be held unenforceable. In re Metoprolol Succinate Patent Litigation, United States Court of Appeals for the Federal Circuit, No. 06-1254.

AstraZeneca sued after Andrx filed an Abbreviated New Drug Applications (ANDA) seeking FDA approval to market generic versions of Toprol-XL®, which Astra claimed infringed its patents pursuant to 35 U.S.C. § 271(e).

Astra sells metoprolol succinate in “extended release” forms under the brand name Toprol-XL®. Metoprolol is a therapeutically active compound, which can form salts by reaction with acids and is used in the treatment of angina, hypertension, and congestive heart failure. Metoprolol succinate is the salt of metoprolol with succinic acid.

In 1971, an Astra employee synthesized metoprolol succinate as well as the tartrate and sulfate salts of metoprolol and chose to commercialize the tartrate salt product. In 1982, another Astra employee synthesized a number of metoprolol salts, including metoprolol succinate.

In 1983, the employees left Astra to join another company, Lejus Medical AB and filed a patent application on delayed and extended release dosage forms of pharmaceutical compositions, including metoprolol succinate

As these things go, Astra of course noticed the publication of the application and commenced a transfer of ownership action with the Swedish Patent Office asserting that its employee invented metoprolol succinate. Astra and Lejus subsequently settled the ownership dispute when Lejus agreed to divide claims to “metoprolol succinate” and to a “pharmaceutical composition, characterized in that the active substance is metoprolol succinate” and to assign the divided claims to Astra.

Both before and after the US filing on two patent applications, Astra’s in-house counsel asserted to Lejus that Nitenberg, not Appelgren and Eskilsson, was the inventor of metoprolol succinate. But, Astra never revealed the inventorship issue to the USPTO during the prosecution of the two patents.

The CAFC reviewed the finding that the patent was invalid for double patenting noting that “[n]on-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.”

Astra tried arguing that the district court erred in concluding that Claim 8 of the ‘318 Patent and Claim 1 of the ‘154 Patent recited a species/genus relationship stating that the claims define an element/combination relationship. But, the CAFC said that such disputes “about the characterization of the relation between the two claims” in a double patenting context are irrelevant:

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 conced[ed] that the differences between B and B1 are not material and would have been obvious to a person having ordinary skill in the art.” 124 F.3d at 1463. 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.2 See also Geneva Pharms., Inc. v. GlaxoSmithKline PLC, 349 F.3d 1373, 1382-83 (Fed. Cir. 2003) (holding that later patent claiming pharmaceutical composition was obvious variant of earlier patent claiming pharmaceutical composition with “enhanced storage stability, the closed container, [and] the packaged unit-dosages”).

The court noted that In re Schneller, 397 F.2d 350 (C.C.P.A. 1968), is a later issued decision that refutes the suggestion that under the previous holdings of Walles, Allen, and Heinle, a patentee may claim an element after claiming the combination without fear of double patenting.

Judge Schall dissented noting that

I agree with the district court that, distilled to its essence, claim 8 of the ‘318 patent claims an oral pharmaceutical composition that has (i) a core that contains one of eleven possible active ingredients (metoprolol succinate being one of the eleven), (ii) an inner coating surrounding the core (that allows a controlled release of the active ingredient), and (iii) an outer coating (that resists dissolving in the stomach, with the goal of releasing the active ingredient close to or within the colon).

Claim 1 of the ‘154 patent, which is the sole claim of that patent, claims the compound metoprolol succinate. ‘154 patent, col.2. l.36. As just seen, metoprolol succinate is one of the possible active compounds of the composition of claim 8 of the ‘318 patent.

I believe that what is patented by claim 8 of the ‘318 patent is a three-element composition having (i) a core with any one of eleven possible compounds, one of them being metoprolol succinate; (ii) an inner coating; and (iii) an outer coating. Anything less than a compound with all three of these elements is not what is claimed. See General Foods, 972 F.2d at 1280 (“There is a claim 1 [of the ‘619 patent] and the first step of its 9 recited steps is designated ‘(a).’ . . . [S]tep (a) is not ‘claimed’ in the ‘619 patent, nor is it ‘patented’ or ‘covered’ . . . What is patented by claim 1 of ‘619 is a 9-step caffeine recovery process, nothing more and nothing less.” (emphases in original)). In contrast, what is claimed by claim 1 of the ‘154 patent is a single compound: metoprolol succinate.

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    Was the original NDA patent has expired for Toprol XL ER Tablets of Astra Zeneca in USA. Is there any ANDA Molecule marketed at present in USA on Metoprolol Succinate ER Tablets