As mentioned in the article they are very effective at preventing smaller companies from producing generic versions based on expired patents. Then they just stop manufacturing the old drugs so there is no supply.
However, if a brand manufacturer has an old product delisted, then physicians can no longer prescribe generic equivalents. That's become more and more common.
However, there is a workaround: compounding pharmacies. To my knowledge, accredited compounding pharmacies can make, on a customer-by-customer basis, any product that the FDA has ever approved. And many of them are mail-order pharmacies. In my experience, prices are comparable to mass-market generics, or lower.
>However, if a brand manufacturer has an old product delisted, then physicians can no longer prescribe generic equivalents. That's become more and more common.
Why is the ability to prescribe a drug tied to whether the branded version in still "listed"?
Also: https://www.accessdata.fda.gov/scripts/cder/ob/index.cfm
And: https://www.drugs.com/history/
Physicians can only prescribe FDA-approved drugs. Only brand drugs are approved on their own. Generic drugs are approved, with much less documentation required. There's no need to demonstrate effectiveness, safety, etc. Applicants must only demonstrate that products are therapeutically equivalent to approved brand drugs. That's mainly about chemical identity, purity, and rate and degree of absorption.
At Drugs@FDA, search for a brand name. If there are generics, you'll see "Therapeutic Equivalents for NDA ...". Clicking that will display links to them.
If there's no listed brand drug, there's nothing for a generic to be equivalent to.
But the real reason is almost always that they have a new version, which costs much more, and they don't want competition from inexpensive generics to their old product.
There have been some antitrust suits over that. I don't know how they turned out.