Osteoarthritis of the knee can cause significant
disability. It causes pain, stiffness and limits movement. Besides the usual
pain killers and anti-inflammatory drugs used to control the symptoms, a number
of new drugs are being tried out that could modify the course of the disease
itself and provide relief to the patient. These drugs are referred to as
disease-modifying osteoarthritis drugs (DMOAD).
Doxycycline is one of the drugs being tried out to
check if it qualifies for being a DMOAD. It belongs to the tetracycline group
of antibiotics. Doxycycline is currently used for a number of bacterial and
other infections. It has been found to
inhibit metalloproteinase, an enzyme which contributes to degeneration of
cartilage in the joints.
Some prior studies have indicated that doxycycline
may slow the progression of osteoarthritis.
A study was conducted in Netherlands to evaluate the
effect of doxycycline on pain and daily functioning in patients with knee
osteoarthritis. The patients received either doxycycline or a similar appearing
inert drug called a placebo for 24 weeks.
The study found that 27% patients in the doxycycline
group and 35% patients in the placebo group showed a response to treatment. This shows that doxycycline is not
effective in reducing symptoms of pain, stiffness or improving function of the
knee joint in patients with knee osteoarthritis. On the contrary, it was
associated with more side effects.
Discontinuation of treatment was more
common in patients taking doxycycline as compared to those taking placebo.
doxycycline cannot be currently recommended to relieve symptoms in patients
with knee osteoarthritis.
Further research with synthetic metalloproteinase inhibitors that can
improve symptoms in osteoarthritis without producing excessive adverse effects
et al; The effects of doxycycline on reducing symptoms in knee osteoarthritis:
results from a triple-blinded randomised controlled trial; Ann Rheum Dis 2011; doi:10.1136/ard.2010.147967