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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.
For more information on OA consult www.arthritis.ca or www.arthritis.org.
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The information in this newsletter was prepared and reviewed
by pharmacists for the Canadian Pharmaceutical Journal.
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Ask Your Pharmacist newsletter is produced through
an unconditional educational grant from APOTEX/PACE. |
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