Marketing of legal prescription drugs can be restricted in certain ways, but it has to be allowed unless we modify the First Amendment. Freedom of expression is a fundamental right and can't be casually eliminated just because we don't like the results.
Advertisements for prescription drugs are very heavily restricted in the US. And, as far as I know, companies selling prescription drugs may not encourage doctors to use them arbitrarily.
I don’t know whether anyone has ever tested the constitutionality of the relevant laws and regulations, but they exist and are enforced.
Is that the overwhelming opinion of legal scholars?
I think I would be just fine with a change like that. If sales of a product can be restricted, why should advertising for that product need to be unrestricted?
It doesn't feel to me like advertising is more of a fundamental right than engaging in sales.