Given the issue with counterfeit material in their warehouses, I don’t even know what they could do to make me trust their control of the drug supply chain.
Unless something has gone horribly wrong, I doubt Amazon Pharmacy is looking to be a "marketplace" with third party sellers like that.
Removal of the algorithmic "Amazon's Choice" label.
Human review of all listings, including changes to them.
Drastic reduction in number of sellers, show the seller company's age w/Amazon as well as the age of the listing and revision history.