The agreement is the culmination of a court battle since 2008 when Impax first informed Pfizer of its application for FDA approval for generic Detrol LA, which is produced as extended-release capsules. Impax has its own proprietary controlled-release drug delivery technologies and formulation skills to create physiologically identical generic versions of brand-name products. Detrol and Detrol LA are lucrative targets, given that they generated US$883 million in global sales in 2011 for Pfizer. Impax currently has 39 Abbreviated New Drug Applications pending, at least seven of which have first-to-file or first-to-market potential, according to the company website.

Meanwhile, a 2010 lawsuit to prevent Mylan Pharmaceuticals from marketing a different generic form of Detrol LA has yet to reach conclusion. Reuters reports that the primary patent for Detrol LA expires in September 2012, while the patents for three additional Detrol formulations expire in 2020.

Pfizer and Impax are not revealing the details of the agreement, which adds to a growing concern over lack of transparency in settlements between pharmaceutical companies and generic producers.

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