DEAR PEOPLE’S PHARMACY: Long ago, I took Celebrex for my arthritis and then was switched to celecoxib. Most of the generics do not work for me, but Greenstone was great. It made an authorized generic that was just like Celebrex.

Then suddenly, I could not find any pharmacy to fill my much-needed prescription with Greenstone brand celecoxib. Greenstone had been absorbed into a company called Viatris, which discontinued it.

I’m completely frustrated. Pharmacies have been filling my prescription with generic celecoxib from a lot of different manufacturers. All of these medicines are practically useless. It would be helpful if somewhere there was a central, continually updated site to find authorized generic manufacturers.

I continually question why I’m taking something that doesn’t work but still has potential NSAID risks. However, going cold turkey has turned out badly for me every time I’ve tried!

A. An authorized generic is a medicine licensed from the brand name company and made to the exact same specifications, including the inactive ingredients. Sometimes an authorized generic might be made on the same manufacturing line as the brand name.

One company, Prasco, has made a list of authorized generics (authorizedgenerics.com). Unfortunately, it is not up to date. Greenstone, which used to make an authorized generic version of the NSAID Celebrex, has indeed disappeared.

You might want to consider purchasing brand name Celebrex from a legitimate Canadian pharmacy. While this would run $460 to $600 for a month’s supply in the U.S., a Canadian online pharmacy can provide 100 pills for around $200, sourced from Canada.

You can find that information through PharmacyChecker.com, which vets its sources. That is important because not every online pharmacy proclaiming itself “Canadian” is legitimate.

You can learn more about finding and utilizing Canadian pharmacies in our “eGuide to Saving Money on Medicines.” This online resource is available under the Health eGuides tab at www.PeoplesPharmacy.com.

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In their column, Joe and Teresa Graedon answer letters from readers. Write to them in care of King Features, 628 Virginia Drive, Orlando, FL 32803, or email them via their website: www.PeoplesPharmacy.com. Their newest book is “Top Screwups Doctors Make and How to Avoid Them.”