Common Drug Found To Reduce Cartilage Loss In Knee Osteoarthritis
INDIANAPOLIS - A common antibiotic may help control the pain and joint
damage of knee osteoarthritis, according to a recent study led by researchers
at the Indiana University School of Medicine.
Researchers at six sites studied the effect of doxycycline over a 30-month
period on women with knee osteoarthritis. Doxycycline is a member of the
tetracycline family of antibiotics.
Kenneth D. Brandt, M.D., professor of medicine and of orthopaedic surgery
and director of the Section of Multipurpose Arthritis and Musculoskeletal
Diseases Center at the IU School of Medicine, was the principal investigator
for this National Institutes of Health study.
"This study is particularly noteworthy because it is the first one
to convincingly demonstrate a pharmacologic effect in slowing cartilage
damage in patients with osteoarthritis," says Dr. Brandt.
The study looked at the progression of osteoarthritic cartilage loss
and knee pain in 431 women between the ages of 45 and 64 years, all of
whom were overweight. Study participants had standard X-ray evidence of
osteoarthritis in only one knee at the beginning of the trial.
Participants were randomly assigned to receive either doxycycline in
the amount of 100 milligrams twice daily or a placebo.
Doxycycline treatment resulted in a 33 percent decrease in the rate of
cartilage loss as shown in the X-rays. Although, doxycycline slowed the
progression of cartilage damage in the arthritic knee, it did not significantly
affect the knee that was not arthritic at the outset of the trial.
That is not surprising, Dr. Brandt says, because the underlying mechanisms
of joint damage respond differently to treatment at different stages of
the disease. He added that the positive effects seen with doxycycline
did not suggest that osteoarthritis was an infectious disease. This drug
has a unique quality among antibiotics that inhibits the enzymes responsible
for the softening and breakdown of joint cartilage in this form of arthritis,
he said.
In general, reports of pain at the onset of the study were relatively
low. As the study progressed, participants taking doxycycline were less
likely to report clinically significant increases in knee pain in comparison
to the group taking placebo.
There was a direct correlation between frequency of flares of joint pain
and the rate of cartilage loss in the arthritic knee. Those with the most
frequent increases in joint pain exhibited the most rapid loss of cartilage.
"This raises the question of which is the chicken and which is the
egg," says Dr. Brandt. "It has not been clear if the loss of
cartilage results in joint pain or whether other mechanisms that cause
pain, and perhaps joint inflammation, result in cartilage loss. This question
warrants additional study."
The initial results of the study were released in November at the annual
scientific meeting of the American College of Rheumatology. Additional
information on the results of the study will be published in the near
future.
IU School of Medicine staff involved with the study include Steven A.
Mazzuca, Ph.D., professor and senior scientists in the Division of Rheumatology;
Barry Katz, director of the Division of Biostatistics in the IU Department
of Medicine, and Kathy Lane, study administrator.
Other participating sites were the University of Alabama at Birmingham,
Rush-Presbyterian-St. Lukes Medical Center, Northwestern University Medical
Center, University of Pittsburgh Medical Center and the Arthritis Research
Center Foundation in Wichita, Kan.
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Media Contact: Mary Hardin
317-274-7722
mhardin@iupui.edu
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