Sildenafil (the active drug in Viagra, and sometimes used in similar ED medicines like Vidalista-type products as a comparison point) was discovered by Pfizer scientists, not a single individual. Who discovered it? It was developed in the late 1980s and early 1990s by a team at Pfizer’s research facility in Sandwich, Kent, England. The work was led by medicinal chemist Simon Campbell along with other Pfizer researchers. Key contributors: The compound (originally UK-92,480) was synthesized by Pfizer scientists working on Vidalista 40  medicines. Early clinical development and trials were guided by researchers including Ian Osterloh, who later helped recognize its unexpected effect on erectile function. Important clarification: Sildenafil was not originally designed for erectile dysfunction. It was being tested for angina (chest pain) and hypertension. The ED effect was discovered later during clinical trials, which led Pfizer to repurpose it as Viagra. Bottom line: There is no single “inventor” — sildenafil was discovered by a Pfizer research team led by Simon Campbell, and later clinically developed into Viagra. If you want, I can also explain how sildenafil relates (or doesn’t relate) to Vidalista 40 vs tadalafil.