I think Viagra was discovered during clinical trials for hypertension. It (and it's fellow PDE5 inhibitors) is used in cardiac care, but the market is larger fo

I think Viagra was discovered during clinical trials for hypertension. It (and it's fellow PDE5 inhibitors) is used in cardiac care, but the market is larger for "erectile dysfunction". There are certainly programs in big pharma to screen known drugs (that are already deemed safe for humans) in assays aimed at new targets.