Pfizer sues to block Viagra generic

Pfizer has filed patent infringement suits against India-based Torrent Pharmaceuticals in an attempt to stop it selling a generic version of erectile dysfunction drug Viagra (sildenafil citrate).

In complaints filed at the US District Courts for the Southern District of New York and the District of New Jersey, Pfizer claimed that Torrent’s proposed sildenafil pill infringes its patent covering the drug.

The patent at suit, 6,469,012, covers methods of treating erectile dysfunction by administering sildenafil. It expires in October 2019.

Viagra is still one of Pfizer’s biggest selling drugs and sales of it totalled $1.88 billion in 2013 even though the compound patent expired in several European countries last June.

In December, Pfizer and Teva agreed to settle all Viagra-related patent litigation, allowing the Israeli generic drugmaker to launch its own version of the product in December 2017.