The first generic version of sildenafil, which is the active ingredient in medications like Tadalista (which contains tadalafil), came after the original sildenafil (branded as Viagra) was developed by Pfizer. However, Viagra (sildenafil) was originally patented by Pfizer and first released in 1998 for the treatment of erectile dysfunction. After the patent for sildenafil expired in 2013, several pharmaceutical companies began producing generic versions of sildenafil. The first generic sildenafil was released by several manufacturers, with Teva Pharmaceuticals and Sandoz being among the first to introduce generic sildenafil after the patent expired. Tadalista, on the other hand, is a generic version of tadalafil, which was originally developed by Eli Lilly and marketed under the brand name Cialis. After Cialis’s patent expired, generic versions like Tadalista started being manufactured by various pharmaceutical companies, offering a more affordable option for consumers.