I tend to think about drug misuse, rather than drug abuse, since not taking certain drugs can be just as irrational and damaging as taking too many drugs.
But basically I think people should use drugs as tools to maximize their utility based on their needs and values. And I think that drug misuse is anything that leads to significantly suboptimal utility that's clearly not justifiable by any sort of internally coherent reasoning.
That seems like an unnecessarily abstract way of saying "make good choices".
Drug abuse seems straight forwardly defined as using a drug for purposes other than as prescribed. Not following the schedule or following it when it is unwise to shouldn't be considered abuse as long as you are still using it to manage pain. Of course that boils down to intent, which is hard to determine.
I tend to think about drug misuse, rather than drug abuse, since not taking certain drugs can be just as irrational and damaging as taking too many drugs.
But basically I think people should use drugs as tools to maximize their utility based on their needs and values. And I think that drug misuse is anything that leads to significantly suboptimal utility that's clearly not justifiable by any sort of internally coherent reasoning.