## Facts

- Procter & Gamble Co. (P&G) owned U.S. Patent No. 5,583,122, claiming the compound risedronate, compositions containing it, and methods of treating disease using it; risedronate was the active ingredient in Actonel®.
- P&G previously obtained U.S. Patent No. 4,761,406, which claimed an intermittent dosing regimen using certain bisphosphonates, including a 2‑pyridyl analog (2‑pyr EHDP), but did not claim or disclose risedronate.
- P&G’s researchers tested hundreds of bisphosphonate compounds and reported that efficacy and toxicity could not be reliably predicted from structure, reflecting unpredictability in the field.
- Teva filed an ANDA seeking approval to market generic risedronate and provided notice to P&G.
- P&G sued Teva for infringement in the District of Delaware; Teva did not contest infringement but asserted invalidity based on obviousness and obviousness-type double patenting.
- Teva’s validity theory relied on structural similarity between risedronate (3‑pyr EHDP) and 2‑pyr EHDP from the earlier patent, arguing a skilled artisan would have been motivated to make risedronate with a reasonable expectation of success.

## Issues

1. Whether Teva proved by clear and convincing evidence that the asserted claims would have been obvious under 35 U.S.C. § 103 in view of the prior art, including P&G’s earlier regimen patent and related bisphosphonate references.
2. Whether the asserted claims were invalid for obviousness-type double patenting over the earlier regimen patent because the later compound, composition, and method claims were an obvious variation of the earlier claims.

## Decision

- The Federal Circuit affirmed the district court’s judgment upholding the asserted claims as valid.
- The court held Teva failed to establish a prima facie case of obviousness because it did not show a sufficient motivation to make risedronate or a reasonable expectation of success in an unpredictable pharmaceutical field.
- The court further held that evidence of unexpected results (improved potency and reduced toxicity) rebutted any claimed obviousness.
- The court rejected obviousness-type double patenting because the earlier patent claimed a dosing regimen, did not claim or disclose risedronate, and Teva did not show the requisite claim-to-claim overlap or obviousness of the specific compound.

## Legal Principles

- Obviousness is a legal conclusion based on underlying factual findings, and invalidity must be proven by clear and convincing evidence.
- Structural similarity between chemical compounds, without more, may be insufficient to establish obviousness where structure–activity relationships are unpredictable; the challenger must show both a motivation to make the claimed compound and a reasonable expectation of success.
- Evidence of unexpected results, including superior efficacy and improved safety relative to what the prior art would predict, can rebut an obviousness case and is especially weighty in unpredictable arts.
- Obviousness-type double patenting requires a meaningful comparison of the claims; a later compound claim is not invalid merely because an earlier patent claims a regimen involving other compounds, absent proof that the later claims are not patentably distinct.

## Conclusion

The Federal Circuit upheld P&G’s risedronate patent because Teva did not prove that a skilled artisan would have been motivated to make risedronate with a reasonable expectation of success, and P&G’s showing of unexpected potency and lower toxicity further defeated obviousness; Teva also failed to establish obviousness-type double patenting given the earlier patent’s regimen focus and lack of risedronate disclosure.


Procter & Gamble Co. v. Teva Pharmaceuticals USA, Inc., 566 F.3d 989 (Fed. Cir. 2009)