Osteoarthritis Drugs

Osteoarthritis occurs in 70% of people by age 80. Marie J. Craig-Chambers, BScPhm, Southlake Regional Health Centre, Newmarket, Ontario

Osteoarthritis (OA) occurs in 70% of people by age 80. It is caused by a loss of the cartilage at the ends of bones and the laying down of abnormal new bone (called osteophytes or bone spurs). Unlike rheumatoid arthritis, which may affect the whole body, OA is specific to the joint area. OA most commonly causes wear and tear on the hips, knees, base of the thumb, big toe, neck and back.

Treatment is aimed at reducing pain, and improving function and the capacity to exercise. Muscular strength to support a painful joint is imperative. X-ray changes often do not correlate with pain, since 50% of people with X-ray-proven OA have no pain. There are currently no medications that slow down the progression of OA.

If pain is mild and intermittent, pain medications are only used when needed. If regular pain medication is needed, acetaminophen has the best benefit to risk ratio. Most people with OA don’t take enough acetaminophen: either too small a dose, or not often enough to effectively relieve pain. Regular or extra strength products need to be taken four times daily, while the long acting tablets should be taken every eight hours.

If acetaminophen is not effective, or if signs of inflammation – swelling, heat, redness, and pain – are present a non-steroidal anti-inflammatory drug (NSAID) may be beneficial. Effectiveness should not be assessed until after at least 2-4 weeks of continuous NSAID therapy. About 7 out of 10 patients will derive benefit from any one NSAID. Some NSAIDs may be better tolerated than others and finding the right match can be challenging. Only one NSAID should be taken at any given time. That means no extra ibuprofen or ASA, including herbal sources of ASA (i.e., willowbark, meadowsweet). A small, once-daily dose of ASA prescribed by your doctor is an exception.

If a joint is very painful, your doctor may suggest a corticosteroid injection. The knee, hip, and base of the thumb are common injection sites. The fluid in your joint acts as a lubricant. Injections of synthetic joint fluid (viscosupplementation) may be recommended for the knee in some patients. It can be done at any stage of the disease, but works best in the early stages. The injections are expensive but may provide relief for up to 6 months in some patients and may help ‘buy time’ before a total knee replacement is required. Joint replacements (knee and hip) are indicated when severe pain occurs, not only with activity, but also at night, limiting sleep and quality of life.

Unregulated products like glucosamine (obtained from shellfish) and chondroitin (from cattle or sharks) are also promoted for pain relief of OA. These may be helpful for some but the risk to benefit ratio has yet to be determined and studies show that the products do not always contain what is stated on the bottle.