Background
Nalpropion Pharmaceuticals held patents covering Contrave, an FDA-approved prescription weight loss medication that combines two drugs — bupropion (an antidepressant commonly sold as Wellbutrin) and naltrexone (an opioid antagonist used to treat addiction). The drug’s basic ingredients were long known individually, but Nalpropion argued the specific combination and dosing regimen represented a patentable invention.
Actavis sought to enter the market with a generic version of Contrave by filing an Abbreviated New Drug Application (ANDA), challenging the validity of Nalpropion’s patents under the Hatch-Waxman Act. After bench trial, the district court found the asserted patent claims invalid as obvious. Nalpropion appealed.
The central dispute was whether a skilled formulator in 2002–2003 would have been motivated to combine bupropion and naltrexone at the claimed doses, and whether the combination produced unexpected synergistic effects sufficient to overcome an obviousness challenge.
The Court’s Holding
The Federal Circuit affirmed invalidity. The court agreed that the prior art provided a clear motivation to combine bupropion and naltrexone for weight loss — both drugs were independently known to reduce appetite and weight, clinical researchers had already studied the combination, and a 2001 clinical trial had shown promising results with the combination at doses overlapping the claimed ranges.
Nalpropion argued that the combination produced unexpected synergistic weight loss — meaning the combination worked better than the sum of its parts. The Federal Circuit rejected this argument, finding that the record evidence did not establish true synergy. The data showed that the combination outperformed either drug alone, but the court found the district court’s factual finding that this effect was not truly unexpected or unpredictable was not clearly erroneous. Because the prior art already suggested the combination would work better together, the improved efficacy was within ordinary expectation.
The court also rejected secondary considerations of non-obviousness, including commercial success, finding that the commercial performance of Contrave was attributable to the FDA-approved indication and marketing rather than to any novel technical advance in the patents.
Key Takeaways
- For combination drug patents, prior art showing that each component individually produces the desired effect creates a strong motivation to combine, even without a specific suggestion to do so.
- Claims of unexpected synergy must be demonstrated with rigorous comparative data showing the combination outperforms what prior art would have predicted — merely outperforming individual components is not enough if that result was foreseeable.
- Commercial success as a secondary consideration carries less weight when success may be attributable to regulatory approval, marketing, or insurance coverage rather than to the patented innovation itself.
- Overlapping prior art ranges for a claimed dosage create a presumption of obviousness that requires more than anecdotal clinical benefit to overcome.
Why It Matters
This decision is an important data point for pharmaceutical patent litigation, particularly for combination drug therapies where generic manufacturers regularly challenge branded drug patents. The case illustrates the high bar that patentees face when their claimed innovation is a combination of two known, FDA-approved drugs with overlapping known uses.
For pharmaceutical companies developing combination therapies, Nalpropion reinforces the importance of generating compelling, well-controlled clinical data showing unexpected synergy during development — not just after the drug is approved. Evidence that surfaces primarily in litigation, rather than from contemporaneous lab notebooks and studies, receives less deference. The decision also signals that commercial blockbuster status alone cannot cure a weak technical case for patentability.