Doctors CAN prescribe it. There is no prohibition against it.
They can prescribe it, but only in a hospital setting. No outpatient prescriptions, which is an impediment. Not completely positive about this ...
In some states there are prohibitions against off label prescription.
Leveled by the phamacy boards
In others it may only be used once hospitalized so you have to be really sick, and it does not work so well
There is downright hostility and scorn by some medical orgs against using it, which intimidates doctors and their managers
They have been indoctrinated to wait for clinical trials ( which could kill the untreated patients in the control group..,would you sign up?) and peer reviewed studies which take months or years
And there is an amazing amount of TDS on twitter by some very credentialed and high placed DRs
So the answer is yes...DR can refuse to prescribe
You can get better access to these drugs in third world countries
In some states, doctors cannot prescribe it except in hospital.
Besides the medical board, the pharmaceutical board is telling pharmacists not to fill it.