Licorice-Based Drug May Fight SARS

June 12, 2003 -- An antiviral drug derived from licorice roots may turn out to be an effective SARS treatment. Preliminary laboratory tests show that the drug, called glycyrrhizin, is better than several other antiviral drugs at preventing the SARS virus from multiplying.

Since the SARS (severe acute respiratory syndrome) outbreak began several months ago, researchers worldwide have been working at a frantic pace to develop a treatment for the disease. No new treatments have been found to be effective at stopping the previously unknown coronavirus associated with SARS.

But a recent comparison of several currently available antiviral drugs published in the June 14 issue of The Lancet suggests the licorice-derived drug glycyrrhizin may have potential as a SARS treatment.

Researchers at the Institute of Medical Virology at Frankfurt University Medical School in Germany tested the antiviral activity of five commercially available drugs (ribavirin, 6-azauridine, pyrazofurin, mycophenolic acid, and glycyrrhizin) against SARS virus samples taken from two patients with SARS in the laboratory.

They found that of all the drugs, glycyrrhizin was the most active in stopping virus replication, which is a key component of treating the illness caused by SARS.

Previously, glycyrrhizin has been used to treat patients with HIV and hepatitis C, but researchers say they aren't exactly sure how the drug works against the SARS virus.

Side effects of glycyrrhizin include raised blood pressure and lowered potassium levels. But researchers say that since these side effects of the drug are known, they can be monitored and controlled for. They also add that treatment of SARS should be needed only for a short time and may result in fewer side effects than are typically associated with long-term use of the drug.

The antiviral drug ribavirin was used extensively in Hong Kong to treat some of the initial SARS patients, but researchers say the drug can have many toxic effects.

Although these early results are promising, much more research -- including tests of the drug in humans with SARS -- will be needed before the drug can be considered for widespread SARS treatment.

SOURCE: The Lancet, June 14, 2003.