Pfizer TB drug joins shortage parade after potency warning

Yet another tuberculosis drug has joined the FDA's list of scarce medicines. Pfizer's ($PFE) version of the injectable antibiotic rifampin is now in short supply, thanks to manufacturing delays, the agency reports. Sanofi's rifampin-and-isoniazid combination capsule, Rifamate, hit the shortage list last week.

In Pfizer's case, the shortage notice closely follows a warning about problems with certain rifampin vials. In a March 18 letter, the company notified wholesalers and healthcare providers that 27 lots of the drug might not meet potency standards. Supplies of the drug are expected to run short through June, the FDA says.

Pfizer's Rifampin for Injection is shipped in powdered form for reconstitution. The affected vials contain brown or black powder, rather than the standard red. Pfizer instructed healthcare professionals to inspect their rifampin vials before dispensing or administering it, to make sure the powder is the correct color. The letter included photos of "acceptable" and "unacceptable" vials and reconstituted solution.

Discolored product should be discarded, the company said. Wholesalers don't need to return the product they still have, but should let all customers know about the potential problems. "Pfizer is currently investigating this matter," the letter states.

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