Dr Stephanie Kaye-Barrett
, Consultant Rheumatologist at The Physicians’ Clinic, provides an update from the 2013 meeting of the British Society of Rheumatology on the drug strontium ranelate. This has already approved in osteoporosis but clinical trial data now suggests that it may be able to modify the course of disease in knee osteoarthritis.
“Professor Cyrus Cooper of the University of Southampton in the UK and his group have done a three year clinical trial looking at how people with knee arthritis have responded to strontium ranelate and the results are very encouraging
,” explains Dr Kaye-Barrett.
“The Southampton group showed that patients given 2g of strontium ranelate each day experienced less pain over three years of treatment compared to patients given a placebo. Knee radiographs also showed that patients taking the drug had less joint space narrowing, a very positive sign that joint degeneration had been slowed down,
” Dr Kaye-Barrett adds.
What does strontium ranelate do?
This drug is effective in osteoporosis because it boosts the formation of new bone while slowing the reabsorption of existing bone. The net result is that women with osteoporosis lose much less bone, or even start to strengthen their bones.
Like all drugs, strontium ranelate was tested rigorously in clinical trials and these produced a lot of data. Later analysis from two trials revealed some very encouraging signs:
- Strontium ranelate-treated patients produced much less of a marker called collagen type II C-terminal telopeptide in their urine. This showed that less of their cartilage was being lost.
- X-rays also showed that spinal arthritis in patients treated with the drug had progressed more slowly.
Disease modifying drugs and rheumatoid arthritis
The suggestion that strontium ranelate might affect the structures of the joints is very important. Disease modifying antirheumatic drugs (DMARDS) have had an enormous impact on the treatment of rheumatoid arthritis. DMARDS act on the structures of the affected joint, slowing and sometimes halting the changes that lead to swelling and pain. No such disease modifying drugs have been approved for osteoarthritis; strontium ranelate might be one of the first.
What do these results mean for patients with osteoarthritis?
Dr Stephanie Kaye-Barrett says: “This study is exciting because it has found an agent (strontium ranelate) that reduces pain and that seems to slow the rate of cartilage loss, a fundamental problem in patients with osteoarthritis.
“This research is a huge breakthrough for arthritis sufferers. Major advances have been made in the last 10 years for patients with inflammatory (immune based arthritis) such as rheumatoid arthritis. In stark contrast, very little has been found to alleviate the pain and slow the progression of degenerative osteoarthritis. These findings will be welcomed by patients and doctors alike,
” she adds.
At the moment, the drug is only licensed for use in osteoporosis in post-menopausal women. It can only be taken by women who have passed through the menopause, are still under 80 years old and who have no history of heart disease or high blood pressure.
This is because it carries a small but increased risk that people who take it will develop a deep vein thrombosis.
Dr Kaye-Barrett concludes that: “Nevertheless, strontium ranelate could be of great value in women who already take it for osteoporosis, but who also have severe osteoarthritis of the spine or knees.