AIDS drug warning issued by Glaxo

Patients prescribed the AIDS drug Combivir should immediately make sure they got the right pills, the manufacturer says, after people in four states bought Combivir bottles that actually contained another AIDS drug called Ziagen.

The tampering could be dangerous, manufacturer GlaxoSmithKline warned Friday.

About 5 percent of people who take Ziagen can suffer potentially life-threatening allergic reactions -- something patients thinking they were taking Combivir wouldn't have been warned about since that drug doesn't carry the same risk, the company said.

Another problem: Combivir provides HIV patients with two anti-viral medications in one pill, while Ziagen is one completely different anti-viral drug. An unintentional switch could lower the effectiveness of a patient's therapy.

Glaxo makes both drugs, shipping them in pre-sealed bottles. The company said its own investigation had ruled out a manufacturing glitch and that the Ziagen in the mislabeled bottles is real and not tainted -- meaning someone sold Ziagen with a counterfeit Combivir label.

A 60-tablet bottle of Combivir costs about $200 more than the same amount of Ziagen.

So far, four bottles -- in Connecticut, Maryland, Florida and California -- have been discovered, Glaxo said.

The Food and Drug Administration's criminal investigations unit is probing the problem. No illnesses have been reported.

"There is a concern that this was not some simple mix-up in production," said the FDA's Dr. Mark Goldberger.

But "the big concern now is to get the word out," he added, because it is easy for patients to tell the two drugs apart if they know to look:

-- Combivir is a white capsule-shaped tablet engraved with "GX FC3" on one side.

-- Ziagen is a yellow capsule-shaped tablet engraved with "GX 623" on one side.

The Combivir bottles' label shows a photograph of the drug to compare.

Patients should immediately check that their Combivir bottles contain the right drug -- and pharmacists should open new bottles in front of the customer so both can see if it's really Combivir before the patient leaves the store, Glaxo spokeswoman Mary Anne Rhyne advised.

Anyone with questionable medication should immediately take it to the pharmacist to be checked, and pharmacies should return suspect bottles to Glaxo for investigation.

[Associated Press]