Hundreds of thousands of children in developing countries are hospitalized… (Paula Bronstein / Getty…)
An inexpensive arthritis drug called auranofin has been shown in lab and animal tests to kill the parasites that cause amoebic dysentery and giardiasis, and human trials are expected to start soon. The gold-containing drug, marketed under the trade name Ridaura, has already been demonstrated to be safe in humans, is much more powerful than existing treatments, and could be provided in developing countries for as little as $2.50 per dose, researchers said. If the results hold up in clinical trials, the drug could provide a new way to reduce suffering in both children and adults.
Amoebic dysentery, caused by the protozoa Entamoeba histolytica, passed through contaminated food or water, strikes an estimated 50 million people around the world each year. It kills 70,000 people annually, most of them children in developing countries. The similar parasite giardia strikes 6% to 8% of children in developing countries, causing diarrhea, abdominal cramps and dehydration. The current treatment for both is the antibiotic metronidazole, which has side effects that include nausea, vomiting, dizziness and headache.
A team headed by Dr. James McKerrow, a pathologist at UC San Diego, and parasitologist Anjan Debnath of UC San Francisco, developed an anaerobic screening process to test potential drugs against the amoeba in the laboratory. A key breakthrough came when Iconix Biosciences, a Menlo Park company that was going out of business, offered the researchers their screening library of 900 compounds, all of them approved by the Food and Drug Administration for human use.
The team reported Sunday in the journal Nature Medicine that auranofin successfully killed the parasite in laboratory dishes and that it was about 10 times more effective than metronidazole, suggesting that it could be used at very low doses. "Importantly, it was a drug that has been given to people since 1985," McKerrow said. "So we knew it could be taken orally and was safer than the current drug for amoebas." A single dose might be sufficient to clear an infection, the team said.
Subsequent studies showed that the drug was equally effective in both mouse and hamster models of the disease, sharply reducing the number of parasites and decreasing damage from inflammation and the size of liver abscesses at very low doses. The group then applied to the FDA and has received Orphan Drug status for auranofin, which will accelerate the process of testing. The team is now organizing clinical trials to demonstrate that the drug works in humans.