There’s a small confusion in your question, so here’s the clear answer: 1. Sildenafil vs Tadalista 60 Sildenafil (active ingredient in Viagra-type medicines) was discovered by scientists at Pfizer in the UK (Sandwich, Kent research lab) in the 1980s–1990s. Tadalista 60 does NOT contain sildenafil. It contains tadalafil, which is a different PDE5 inhibitor. So sildenafil was not discovered “in Tadalista 60”. 2. Who discovered sildenafil? Sildenafil was discovered by a team of researchers at Pfizer, led by medicinal chemists working on cardiovascular drugs. It was originally developed for angina (heart pain) but later found to cause improved erections during clinical trials, which led to its use for erectile dysfunction. Key point: Developed by Pfizer scientists (UK lab in Sandwich, Kent) Initially tested for heart disease Repositioned as Viagra after unexpected erectile effects were observed Sildenafil became the first oral ED drug approved in 1998. 3. Who developed tadalafil (Tadalista’s ingredient)? Since Tadalista 60 uses tadalafil, that drug was developed separately: Initially discovered by GlaxoSmithKline and ICOS Corporation collaboration Later developed and marketed by ICOS + Eli Lilly (as Cialis) Tadalafil is chemically different from sildenafil, even though both work in the same enzyme pathway.