I DO have a problem with paying at least 50% more than the next highest spending countries like Switzerland or Norway - all with excellent healthcare systems - probably better than the US (except for the very high-end)
The prior is already happening with the introduction of PA and NPs taking over roles that MD/DOs used to do (for better or for worse, I've seen many discussions on how PA/NP education is very lacking and the bar to qualify is too low, which I agree with).
I don't know much about increasing supply of medicine, but that probably has to do with patent reform and/or FDA approvals for slightly modified medications.
There's also probably something about liability and litigiousness that is a factor of higher prices in the US.