Adams Respiratory Therapeutics, Inc. v. Perrigo Company

Case Name: Adams Respiratory Therapeutics, Inc. v. Perrigo Company, Civ. No. 07-993-GJQ, 2012 U.S. Dist. LEXIS 3288 (W.D. Mich. Jan. 11, 2012) (Quist, J.).  (Prosecution disclaimer/estoppel - A finding in another case that the patentee disclaimed a particular dosage form during prosecution also applies in the instant case for purposes of non-infringement of the same patent). 

Drug Product and Patent(s)-in-Suit: Mucinex^® (guaifenesin); U.S. Pat. No. 6,372,252

Nature of the Case and Issue(s) Presented: Whether plaintiff Adams Respiratory Therapeutics, Inc. ("Adams") disclaimed single-formulation, sustained-release tablets during the prosecution of the '252 patent.  The '252 patent describes a bilayer, modified-release tablet containing distinct immediate-release and sustained-release portions.  Unlike Adams' bilayer product, Perrigo's tablet is a unitary single-formulation, sustained-release tablet.  In a prior litigation, Adams asserted the '252 patent against a similar generic formulation manufactured by Watson Laboratories, Inc. ("Watson") in the United States District Court for the Southern District of Florida.  The Florida district court found that Adams disclaimed unitary single-formulation, sustained-release tablets during prosecution.  On appeal, the Federal Circuit affirmed.  In this case, based on the same rationale as the Watson case, defendant Perrigo attempted to establish that its accused generic formulation also involved single-formulation, sustained-release tablets-similar to Watson's in the prior case-and that it too was entitled to summary-judgment on the issue of non-infringement.

Why Perrigo Prevailed:  Perrigo prevailed because the patented tablet required two separate portions of guaifenesin-a first portion of guaifenesin in an immediate-release formulation, and a second portion of guaifenesin in a sustained-release formulation.  Perrigo successfully persuaded the court that, similar to Watson's generic formulation from the earlier case, its generic tablet was a single-release tablet that did not contain separate portions, as required to meet the claim limitations of the '252 patent.  Adams attempted to escape the consequences of the Federal Circuit's Watson holding, arguing that Perrigo's generic tablets differed from the Watson generic tablets because Perrigo's contained some free guaifenesin on the surface of the tablets, which gave the generic tablets some immediate release properties.  But this was unpersuasive.  The court determined that Adams' effort to divorce structure from process on the grounds that the Federal Circuit said that the two-portion limitation was structural as opposed to functional was unavailing.  The Federal Circuit made it clear that the threshold issue with respect to infringement was whether the accused product was made with a single formulation (noninfringing), or separate immediate-release and sustained-release formulations (infringing).  Adams was required to provide evidence that each portion of the two-portion modified-release tablets were separately formulated, and then later combined to form the tablet in order for the accused tablets to fall within the scope of the claims.  Adams failed to carry that burden.  Adams also contended that the Perrigo generic tablets infringed under the doctrine of equivalents, but the court held that Adams was barred from making this argument under the doctrine of prosecution history estoppel.  Perrigo was granted summary judgment of non-infringement, literally and under the doctrine of equivalents.