Doctors investigating a commonly prescribed antibiotic have found that it can slow the progression and pain of osteoarthritis, suggesting a potential role in treating the disease that affects millions of Americans. Doxycycline, which is used to treat a variety of infections, was taken by a population of obese women between the ages of 45 to 64 for 30 months. Compared to a similar group of women taking a placebo, the antibiotic group had preserved more joint cartilage in the knee at the end of 30 months, and they also experienced less arthritic pain.
The results of the study were presented during the last week of October at the American College of Rheumatology Annual Scientific Meeting in Orlando.
Dr. Kenneth Brandt, Professor of Medicine and Professor of Orthopedic Surgery at the Indiana University School of Medicine, said he and his colleagues decided to study doxycycline in arthritis patients because earlier research showed the antibiotic played a role in preventing the breakdown of an important component of cartilage. That component is called type 11 cartilage.
"We found an enzyme in cartilage that degraded Type 11, and in characterizing it, it had certain biochemical features that suggested it might be inhibited by doxycycline," said Dr. Brandt.
This study of 431 obese women showed that doxycycline certainly had an effect on joint cartilage in the knees. The X-rays of women taking the antibiotic at 100mg twice a day showed a 33 percent decrease in the rate of joint space narrowing compared to the women taking a placebo pill. Joint space narrowing reflects the loss of cartilage between the bones in the knee.
Women taking the placebo complained of greater pain than the women who received the doxycycline. And doxycycline seemed to have a beneficial effect on symptoms of pain in the opposite knee, even when X-rays of that joint were normal.
But is it safe to take an antibiotic for 30 months?
"We had no major problems, no appreciable problems and we watched very, very closely," said Dr. Brandt. "There were no antibiotic resistant infections, nothing out of the ordinary."
In fact, Dr. Brandt said it’s quite possible that patients with osteoarthritis may be able stay on an antibiotic for several years to prevent the progression of the disease. Unlike the non-steroidal anti-inflammatory drugs, such as Vioxx, Celebrex and Alleve to name a few, antibiotics have not been shown to cause ulcers or other gastrointestinal problems if taken over several months.
