Pfizer initiated Viagra’s clinical development in the early 1990s. Initial studies focused on the drug’s potential to treat angina pectoris (chest pain). Surprisingly, these trials revealed a significant side effect: improved erectile function.
This unexpected finding redirected research efforts. Subsequent clinical trials specifically evaluated Viagra’s efficacy and safety in treating erectile dysfunction (ED). Researchers conducted numerous Phase 1, 2, and 3 trials involving thousands of men with varying degrees of ED. These trials meticulously documented improvements in erectile function, alongside assessments of side effects.
Data analysis played a pivotal role. Statisticians rigorously analyzed the results, comparing Viagra’s impact to placebo groups. This rigorous evaluation was necessary to demonstrate clear efficacy and a favorable risk-benefit profile.
| Phase 1 | Safety and tolerability | Established safe dosage range |
| Phase 2 | Efficacy and dosage optimization | Confirmed improvement in erectile function |
| Phase 3 | Large-scale efficacy and safety confirmation | Demonstrated significant improvement in ED symptoms across various patient populations. |
The robust data generated from these studies formed the basis of Viagra’s application for regulatory approval from the FDA. The FDA reviewed the extensive data package, including results from all clinical trials, before granting approval for marketing in March 1998.
