This post was first published on June 7, 2011. Pfizer Inc. filed a suit against Watson Laboratories, on June 1, 2011 in the United States District Court for the Southern District of New York seeking to prevent Watson from commercializing sildenafil citrate tablets prior to the expiration of Pfizer’s Viagra. Watson's sildenafil citrate tablets are a generic version of Pfizer Inc.'s Viagra, which is indicated for the treatment of erectile dysfunction (ED). Sildenafil citrate enhances the effect of nitric oxide, which…