Osteoarthritis affects 21 million people in the United States, which amounts to more than 10 percent of American adults. Osteoarthritis treatments have focused on controlling pain associated with loss of articular cartilage, subchondral sclerosis, and the formation of osteophytes. There has been no drug or treatment which was able to target the process of joint destruction though.
A drug which is widely used to treat Paget's disease of bone and osteoporosis may also potentially be able to slow or counteract cartilage damage. It's what researchers are studying. The drug is calcitonin and it is an amino acid hormone produced by the thyroid. Calcitonin is prescribed as a nasal spray or injection.
Calcitonin Study on Female Rats
Researchers are trying to determine whether calcitonin could be a disease-modifying drug used to treat osteoarthritis. A recent study of female rats allowed researchers to conclude that calcitonin may protect postmenopausal women from ongoing pain and disability tied to joint destruction.
The study focused on ovariectomized rats, which researchers said correlates with human menopause. Loss of estrogen has been associated with cartilage degradation. In the study there were 5 study groups of rats. There were rats which had:
- ovariectomy
- ovariectomy plus 60-day release estrogen pellet inserted
- ovariectomy plus 2 mg/kg of salmon calcitonin and 5CNAC (a delivery agent)
- ovariectomy plus 5CNAC
- a sham procedure
Blood samples were taken periodically from the rats and body weight was recorded. At 9 weeks, the rats were euthanized and analyzed. All ovariectomized rats showed evidence of accelerated articular cartilage degradation. Estrogen therapy counteracted the increased rate of degradation. Calcitonin worked even better.
Conclusions About Calcitonin
Researchers concluded that estrogen and calcitonin protected against surface erosions of knee joint cartilage. Calcitonin worked better by totally preventing erosions. Calcitonin treatment may counter both the acceleration of cartilage degradation and increase in surface erosions. Upcoming trials will look for more evidence.
Some researchers, in considering the impact of these study results on human osteoarthritis, wondered if the effect of calcitonin on cartilage would be preventative rather than therapeutic, with the greatest benefit occurring in early osteoarthritis. It should be noted that animal studies sometimes fail to yield promising results in humans, but at this point the study on calcitonin provides hope that there may be a new treatment option down the road.
Source:
The Effect of Oral Calcitonin on Cartilage Turnover and Surface Erosion in an Ovariectomized Rat. Arthritis & Rheumatism. August 2007.
<http://www3.interscience.wiley.com/cgi-bin/abstract/114298010/ABSTRACT>
