> The US funds the manufacture and research on drugs for rare diseases but only while the drug is under patent. Once the drug is out of patent then there is no regulation. These are called "orphan drugs."

This is exactly the opposite of the case. The FDA wanted to encourage manufacturers to conduct new safety and efficacy trials on drugs (that can be out of patent) to treat 'orphan conditions', which are conditions that exist in rare populations, which could be currently off-label indications. Because it is outside of the scope of the FDA, the FDA cannot incentivise you to help this class of underprivileged people by extending your patent monopoly. What it can do, is to give you the exclusive rights to advertise your drug, which, in the US, is a de facto monopoly. Of course, this regulation is highly abused.

https://www.spectrumnews.org/news/drugmakers-manipulate-orph...