Interesting, especially in light of the Feds requiring pharmacies to carry certain OTC drugs, like so-called Plan B contraceptives.
Viagra is prescription only. Probably should be OTC but it does affect blood pressure. That was it's original design and test premise. The primary side effect became the marketable asset.
As far as plan B contraceptives that was purely a political decision by the FDA at the direction of obummer and the feminazis.