Arthritis.Antibiotic doxycycline

A common antibiotic may slow the progression of osteoarthritis.

A new study shows that treatment with the antibiotic doxycycline slowed the deterioration of joint tissue in women with osteoarthritis of the knee.

Doxycycline is used to treat a variety of bacterial infections. Previous lab tests with animal and human tissue showed that doxycycline may help preserve joint tissue, say the researchers. They add that this is the first major study of the antibiotic as a potential treatment for osteoarthritis.

Osteoarthritis is a common form of arthritis that causes progressive destruction of the cartilage that cushions the joints. Common symptoms are joint pain and stiffness. When severe, osteoarthritis can cause loss of movement in the affected joint.
Antibiotic for Osteoarthritis?

In the study, which appears in the July issue of Arthritis & Rheumatism, researchers compared the effects of doxycycline to a placebo in about 400 obese women with knee osteoarthritis. Specifically, they measured the impact of treatment on the joint space in the affected knee. More joint space indicates a loss of cartilage and progression of the disease.

The women were randomly divided into two groups and received either 100 milligrams of the antibiotic twice daily or a placebo for up to two and a half years.

After 16 months of treatment, the study showed that the average loss of joint space in the diseased knee was 40% less among those who took doxycycline vs. the placebo. After two and a half years, the average loss among the antibiotic group was 33% less.

Although these results suggest the antibiotic slowed the progression of the osteoarthritis, researchers say it did not reduce the severity of joint pain reported by the participants.

However, researchers say the average level of pain was low in both groups, which may have provided limited opportunity for the treatment to show an effect on pain.

But doxycycline was associated with a reduction in the number of times the patients reported a 20% or more increase in knee pain.

Researchers say the study suggests that the antibiotic may provide benefits in the treatment of osteoarthritis but more studies will be needed to confirm these results.