I don't know how MM proponents expect it to become a prescribed substance when the clinical trials required for all other prescription drugs have not been done on "medical marijuana" which is the whole, unprocessed plant according to the link I posted earlier.
One of the biggest reasons for required clinical trials is to find out by scientific method whether it actually helps, and to find out if it does more good than harm! (First, do no harm.)
As this research article from National Institutes of Health shows, there are many complexities to both crude cannabis and the prescription drugs made from derived canniboids that remain untested and unresolved:
Cannabinoids in the management of difficult to treat pain
"Even after political and legal considerations, it remains extremely unlikely that crude cannabis could ever be approved by the FDA as a prescription medicine as outlined in the FDA Botanical Guidance document (Food and Drug Administration 2004; Russo 2006b), due to a lack of rigorous standardization of the drug, an absence of Phase III clinical trials, and pulmonary sequelae (bronchial irritation and cough) associated with smoking (Tashkin 2005). Although cannabis vaporizers reduce potentially carcinogenic polyaromatic hydrocarbons, they have not been totally eliminated by this technology."
Cannabinoids in the management of difficult to treat pain