(CNN) -- A relatively obscure drug used to treat mouth sores has made obese mice thin -- and the mice didn't have to eat less or exercise more, according to a study at the University of Michigan.
Doctors at the university will begin studies in human beings later this year. Hopes are high, even though many drugs that work in mice do not work in humans.
"It is a tour de force and offers a new and potentially exciting opening for developments of new anti-obesity drugs -- something which is badly needed," says Dr. George Bray, chief of the Division of Clinical Obesity and Metabolism at Pennington Biomedical Research Center at Louisiana State University.
In the study at the University of Michigan, researchers gave mice a high-fat diet, and they became obese. They then injected the animals with a drug called amlexanox, which has been on the market for more than 15 years to treat canker sores. The mice lost weight, even though they kept eating the same number of calories. When they were taken off the drug, the mice gained all the weight back.
"It could well be that what works for one disease will turn out to work for another, even though that wasn't the original intent," he said.