azathioprine (cont.)

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PREPARATIONS: Tablet: 25, 50, 75, 100 mg. Injection: 100 mg

STORAGE: Azathioprine should be stored at 15 C -25 C (59 F -77 F) in a dry place and protected from light.

PRESCRIBED FOR: Azathioprine is used for preventing rejection of transplanted kidneys. Azathioprine also is used for the treatment of active rheumatoid arthritis.

Non-FDA approved uses for azathioprine include multiple sclerosis, where several clinical trials have shown decreases in relapses but no slowing in progression of the disease. There also is limited data on the safety of azathioprine in multiple sclerosis. Other non-FDA (off-label) uses of azathioprine include Crohn's disease, myasthenia gravis, chronic ulcerative colitis, and autoimmune hepatitis (in combination with prednisone).

DOSING: The initial dose for preventing organ rejection is 3 to 5 mg/kg (oral or IV) daily, starting at the time of transplantation or in some cases 1 to 3 days before transplantation. The initial off-label dose for treating rheumatoid arthritis is 1.0 mg/kg (50 to 100 mg, oral or IV) as a single dose or twice daily. Doses may be increased by 0.5 mg/kg daily up to a maximum dose of 2.5 mg/kg per day. Dosing for other off-label use may vary according to what disease is being treated; in general, off-label use should be done by an experienced medical specialist. Azathioprine should be taken with food.

DRUG INTERACTIONS: Allopurinol (Zyloprim) that is used for treating increased blood levels of uric acid and preventing gout increases azathioprine levels in the blood which may increase the risk of side effects from azathioprine. Therefore, it is important to reduce the dose of azathioprine by approximately 1/3 to 1/4 in patients taking allopurinol. The use of angiotensin-converting enzyme (ACE) inhibitors to control high blood pressure in patients taking azathioprine has been reported to induce anemia (low levels of red blood cells) and severe leukopenia (low levels of white blood cells). Azathioprine reduces blood levels of the blood thinner, warfarin (Coumadin), and thus may reduce the blood thinning effect of warfarin.

Medically Reviewed by a Doctor on 10/28/2014

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