The exact
mechanism of action is not known. It appears to have an effect in lowering
inflammation. This may be because it affects folic acid breakdown. Folic
acid is needed for rapidly multiplying cells and since the inflammatory
cells have a short life, there are the ones most affected. There
is also evidence for anti-bacterial (in the colon) effects of sulfasalizine
How
is sulfasalazine given and what are the possible side effects ?
Sulfasalazine
is to be avoided in patients who are known to be allergic to sulfa group
of drugs or have a condition called porphyria. It is available in the
form of tablets which are enteric coated (a covering), to reduced the
irritation to the stomach. The tablets are available in strengths of
500 mgs and are started in a dose of 1 tablet a day and slowly increased
by one tablet a week to final dose of 4-6 tablets per day. The treatment
is to be continued as long as possible though, the number of people
who remain on Sulfasalazine after 5 years) is about 40% (ie 2 in 5 people).
The common
side effects include skin rash, feeling sick (nausea), diarrhea, loss
of appetite, heartburn, abdominal pain, dizziness, headache and reduction
in the blood counts (meaning fewer blood cells). Symptoms such as sore
throat, fever, any other infection or an unexplained bruising should
prompt a visit to your GP. There may be a change in the colour of your
urine (it may change to orange) and sulfasalazine may stain soft contact
lenses yellow. A transient reduction in the sperm count resulting a
temporary reduced fertility is seen in about 80% of men receiving the
drug. These adverse events usually improve on stopping the drugs. To
reduce the incidence of side effects these tablets are enteric coated
and the dose is built up slowly.
Are
regular blood tests required?
Before
starting the drug a doctor will make sure you have a full blood count,
liver function tests and renal (kidney) function tests. Since most of
the side effects occur in the initial six months of therapy, regular
monthly blood test are conducted for that period. After which the occurrence
of side effects are not as common and so such frequent testing is not
required.
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