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Azathioprine (Imuran) -- Purine analog that decreases metabolism of purines and
also may inhibit DNA and RNA synthesis. Reduces disability and symptoms of CIDP
by suppressing immune-mediated damage to nerves. Initial dose: 50 mg PO qd,
increased gradually to total daily dosage of 2-3 mg/kg/d PO
Therapeutic dose of azathioprine difficult to determine for each patient; some
evidence suggests that elevations of RBC volume (MCV) indicate therapeutic
dosing
Therapeutic response may take >6 mo to become apparent
Side effects
Can lead to various GI symptoms and ulcer formation with delayed healing (use
with prophylactic agent to prevent ulcers); can lead to severe leukopenia,
anemia, and thrombocytopenia (strictly monitor blood counts: obtain CBC count
before treatment, every 1-2 wk for first few months, then monthly; in author's
practice, WBC count of 3000/mL considered warning,
requiring closer monitoring of WBC counts and infection precautions; 2000/mL
considered sign to stop medication)
As immune suppressant, places patients at risk for infections
Monitor hepatic enzymes because of risk of liver failure (same frequency as
monitoring of CBC count); caution should be used if new elevation of liver
enzymes up to twice normal level noted; if stopping drug brings liver enzymes
back to normal, drug can be tried again at later date, although with special
caution; an idiosyncratic reaction can occur within days of initiation of
treatment, including fever, jaundice, nausea and vomiting, and elevation of
hepatic enzymes
Discontinuation of drug usually results in complete resolution of symptoms;
restarting drug does not always result in same reaction but should be considered
carefully
Please read the autoimmune E-Book for permanent treatment
guidelines.
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