Nature of the Case
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Facts
Actavis (P) filed an Abbreviated New Drug Application (ANDA) for a generic counterpart of Zubsolv. Two D patents were challenged by P and the ‘330 patent was held invalid. The '330 Patent explains that opioid-based pharmaceutical products intended for the relief of pain have become a source of addiction, dependency, and abuse. The Patent explains that while buprenorphine has less narcotic effect than a full opioid, addicts were known to dissolve the buprenorphine from the substitution therapy tablet and inject the dissolved buprenorphine intravenously to achieve an enhanced opioid effect. To counteract this abuse, it was known to combine buprenorphine with the opioid antagonis naloxone in substitution therapy. It was common knowledge that the formulations containing buprenorphine to naloxone at a ratio of 4:1 provide the therapeutically optimal balance for sublingual treatment. However, naloxone's 'functional blockade of buprenorphine's action is also only partial and is short-lived in its nature,' and there was a continuing need for improvement in substitution therapy formulations. The '330 Patent is for a sublingual tablet formulation that is less subject to abuse. The formulation enhances the agonist effectiveness of buprenorphine, permitting a reduced amount of buprenorphine in the tablet and thus reducing the amount available on dissolving and injecting the product. Microparticles of buprenorphine are adhered to the surface of carrier particles of citric acid, and the formulation also contains naloxone in the 4:1 ratio. The '330 Patent explains that the buprenorphine in the microparticles acts with little interference from the naloxone, but if the tablet is dissolved in water for injection into the bloodstream, the naloxone will also be dissolved and will antagonize buprenorphine's effects. This new product provides improved treatment of opioid dependence, as compared with the prior art. P argues that this formulation is obvious based on a combination of references, and that improved function and use are irrelevant if the product is obvious. The district court held that although the specific formulation was not shown or suggested in any reference, the new combination would have been obvious to a person of ordinary skill. D appealed.
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