★★☆Single study — solid evidence, such as one good trial or a large observational dataset, but not replicated at the top tier.
Revatio and Viagra are the same drug and not interchangeable
Revatio and Viagra both contain sildenafil and are not interchangeable. Viagra is 50mg once before sex. Revatio is 20mg three times a day for a lung disease.
What the study found
Same molecule, 20mg three times a day, for a lung disease
Revatio and Viagra contain the same drug and are not interchangeable. Viagra is 50mg of sildenafil taken once before sex, at most once in a day. Revatio is 20mg three times a day, every day, for raised pressure in the lung arteries.
The caveat · US labels only, not actual practice
A prescribing label sets doses and rules without publishing the data behind them, and its wording is negotiated between a manufacturer and a regulator. Both of these are the US labels, and neither describes what doctors do outside them.