Malaria Drugs Shelf-Life Possibly Much Longer Than Expected

Joe De Capua | 26 Feb 2009
Voice of America
A new study suggests that one of the most important malaria drugs, artemether-lumefantrine, may remain potent well after its shelf-life was thought to expire. The study, published in the Malaria Journal, says the drug used in artemisinin-based therapy could possibly be used years after its listed expiration date.

In Washington, Richard Tren, director of Africa Fighting Malaria, says, "The drugs that were effective against malaria over the past few decades...have become resistant. The malaria parasite is extremely effective at resisting our attempts to kill it off. And so the new...malaria drugs are these artemisinin combination therapies that are based on an ancient Chinese herbal remedy and then combined with a different drug that has a different mode of action. And by combining the two drugs, you reduce the probability that the parasite will become resistant."

The thinking has been that these newer malaria drugs probably could only be used for up to two years before becoming ineffective. Tren says, "This goes back...(to) when these drugs were first developed and formulated as a combination therapy. The drug regulators gave it a two-year shelf life because we simply didn't know how long it lasts."

Setting a limited shelf life helps protects patients. Tren says, "They do this for good reason. They want to make sure that the drugs we're getting out there are safe and effective. But now we've been using these drugs in some countries for five or six years, sometimes even longer. And it seems though from our initial studies that the drugs are much more stable, that they could last well beyond two years."

There's a call for a more in-depth study of the malaria drugs to determine their true expiration date. Such a study could be done by the US Food and Drug Administration or Swissmedic. Tren says the preliminary study was based on 70 samples that were officially out of date. Tests using thin-layer chromatography and Raman spectrometry indicated nearly all were still effective. Some of the samples were out of date by as much as 58 months.