Contract Research Company Sues to Enforce Stable Antibiotic Mixture Patent

On Monday a case was filed in the District Court of New Jersey by Curia IP Holdings, LLC against Salix Pharmaceuticals, Bausch Health Companies, and Alfasigma USA Inc. and their subsidiaries. The case is regarding infringement of Curia IP’s patents regarding a particular formulation of the antibiotic Rifaximin.

Curia, the complaint explained, is part of “a global contract research and manufacturing organization” that works with drugmakers on topics like “drug discovery and candidate selection, drug development, analytical testing services, active pharmaceutical ingredient (“API”) development and manufacturing, and drug product development and manufacturing in support of commercialization.”

At issue in the case is Rifaximin, a wide-spectrum antibiotic that is effective against a variety of bacteria types. However, the complaint explained that Rifaximin is also susceptible to polymorphism, a phenomenon resulting in a variety of crystalline forms for the compound, including α, β, gamma (“γ”), delta (“δ”), and epsilon (“ε”) forms. Also, the α is susceptible to conversion to β format in the presence of humidity.

The plaintiff has patents on a stabilized format of Rifaximin, which consists of an admixture of type α and β variations in a manner that prevents further conversion or degradation of the types of Rifaximin, as well as ensuring a minimum percentage of type α, which is the clinically more effective variation.

The defendants are accused of selling the Rifaximin α only variation internationally and domestically. However, the α mixture is frequently exposed to sufficient moisture during the shipping process that it converts to the admixture which is patented by the plaintiffs. Plaintiffs accuse the defendants of deliberately permitting this conversion in order to achieve the patented stability without having to file an ANDA application or pay royalties to the plaintiff.

The plaintiffs are suing for patent infringement. They are represented by Locke Lord