CHICAGO, IL. -- October 30, 1997 -- Doxycycline, a common antibiotic used to treat infections and dermatological conditions, has been shown in early studies to slow the progression of -- and may even protect unaffected joints from -- osteoarthritis.

Research in a laboratory model has indicated the drug, a member of the tetracycline family of antibiotics, blocks the action of enzymes involved in the breakdown of joint cartilage, the cause of osteoarthritis. Osteoarthritis affects about 16 million people annually, especially women and particularly those older than 54.

Currently used medications for osteoarthritis, including aspirin, acetaminophen and ibuprofen -- even steroids -- may control pain and swelling but do nothing to stop or slow down deterioration of cartilage.

Although doxycycline is a Food and Drug Administration-approved prescription medication, its use in the treatment of osteoarthritis is experimental and must be tested under controlled, scientific conditions.

Northwestern University Medical School is the only site in the Chicago area and one of just six sites in the country, chosen to conduct a clinical trial to determine if doxycycline can be used to slow the progression of osteoarthritis. Arthritis specialist Leena Sharma, M.D., assistant professor of medicine, is the principal investigator for the National Institutes of Health-sponsored study at Northwestern.

Women who are between the ages of 45 and 64, overweight, with osteoarthritis in one but not both knees and mild, moderate or severe symptoms may be eligible for the study. Women who have had major surgery on their knees, have inflammatory disease, such as rheumatoid arthritis or lupus, or have had an adverse reaction to tetracycline are ineligible. Those with histories of serious stomach, heart, kidney, liver or lung disease also are ineligible for the study.

Several factors increase the risk for development of osteoarthritis: heredity, injury and repeated overuse of certain joints. Extra weight, which adds stress on the knee joint, contributes to the development of osteoarthritis. Overweight women are at greater risk for worsening of their arthritis, which is why they are targeted for this study.

Osteoarthritis of the knee is the leading cause of disability among the elderly population in the U.S. Nearly 70 percent of all people over the age of 60 have evidence of osteoarthritis.

Women selected for the doxycycline study will receive a complete medical history, full physical examination, blood and urine tests and knee x-rays. There is no cost to participate.