Examples of this are rife everywhere - from my own experience, any asthmatic can tell you in the 2000's their rescue inhaler only cost them $15 for the generic - however, when the gas inside the inhaler was changed from a CFC-based propellant to nitrogen, they filed new drug status (for the same ancient drug), purely because they changed the propellant - asthmatics now pay $45 for the same inhaler (with insurance, FYI) with the new gas. Who's to say they won't switch to oxygen or CO2 as a propellant when the next round of patents expire and the prices drop to generic levels?
On the opposite side of the spectrum, herbal remedies can for some things be quite helpful - and some of the "herbal cures" in that realm like Slippery Elm for diverticulitis work very well but are not prescribed by any doctor lawfully as these cures are not tested by anyone officially - because doing so won't guarantee the researchers investment in testing will be paid back because they cannot control who sells that herbal cure afterwards. There are cures in nature that are not being directly researched, presented or even considered by the big pharma community because of this. Many cures in nature are being researched so that the potentially patent-able bits are pulled out for testing and potential commercialization. If they found that chewing a certain leaf or making tea of it cured something important, big pharma would never tell us - not until they pulled the active parts out and sold that to us 15 years later at a premium after extensive testing as well.
I suppose the FDA should be doing this on their own, but that's an extra that's not in their charter..
A list is only as strong as its weakest link. -- Don Knuth