Without an external mandate to keep the price low, this should only happen rarely, because the chain will realize that they're underpricing the drug. If your co

Without an external mandate to keep the price low, this should only happen rarely, because the chain will realize that they're underpricing the drug. If your copay is $10 and they sell it retail for $5, they'll make some kind of differentiation in the labeling to effect price segmentation and maximize the profit from each group of potential shoppers. That way, they'll be able to bill your insurance co $30, you'll pay your $10 copay, and they won't legally be allowed to sell you the cheaper $5 version since it will no longer fit the doctor's Rx. They may keep a few things underpriced so that they can have pharmacists offer the cheaper version and create the impulse/illusion that the chain is looking out for their best interest.