Arthritis Drug Offers Cheap Cure for Dysentery

Sometimes an old dog can learn new tricks - researchers have found that the drug auranofin, used to treat rheumatoid arthritis, can also be used to treat Entamoeba histolytica, a parasite that can cause amebic dysentery and liver abscesses, and Giardia intestinalis, a parasite that can cause diarrheal infection.

A team of scientists from University of California San Diego, University of California San Francisco, and Wake Forest University discovered that auranofin targeted the enzyme thioredoxin reductase used by the amebae to protect itself. Without the enzyme, the amebae are more prone to oxygen-mediated medication. This breakthrough marks a way to combat a worldwide disease in a cheap, low dosage manner.

"This is a drug that you can find in every country," said Anjan Debnath, a postdoctoral fellow at UCSF who led the research and is first author on the paper. "Based on the dosage we're seeing in the lab, this treatment could be sold at about $2.50 per dose, or lower. That cost savings could make a big difference to the people who need it the most."

Entamoeba histolytica is an anaerobic parasitic protozoan that affects up to 50 million people worldwide. Anaerobic means the parasite can grow without oxygen, and sometimes, as in this case, react negatively to it. While some people are simply carriers, up to 70,000 people die a year from Entamoeba histolytica related infections, making it the fourth leading cause of death from protozoan infections.

Giardia intestinalis works by lodging itself in the small intestine where it then feeds on the nutrients from the host. The results can be diarrhea, excessive sulphur-like flatulence (there have been cases where infected person himself vomits from the odor), and a host of other unpleasant symptoms.

The real problem lies in developing countries, where the drinking water, diet, and medical expertise may not be up to the par of developed countries and the usually non-fatal infection can become lethal.

The parasites only affect far fewer people in the United States and is why the FDA has declared it an "orphan drug." An orphan drug is a significant, newly developed or recognized treatment for a disease that affects fewer than 200,000 people a year in the United States.

The current treatment for amebiasis and giardiasis is antibiotic metronidazole, whose side effects include nausea, vomiting, dizziness, and a headache.

The findings were published in the May 20, 2012 edition of Nature Medicine.