The guidelines your healthcare provider will follow when prescribing a dosage for azathioprine depend on factors such as the condition being treated and your weight. Typically, the starting dose for preventing rejection after a kidney transplant is 3 to 5 mg per kg once daily. When treating rheumatoid arthritis, the dose usually starts at 1 mg per kg daily (taken once or divided into two smaller doses).
Azathioprine Dosing: An IntroductionThe dose of azathioprine (Imuran®) your healthcare provider recommends will vary, depending on a number of factors, including:
- The medical condition being treated
- How your body responds to azathioprine (some people do not clear the drug from the body as well as others)
- Your weight
- Other medical conditions you may have
- Other medications you may be currently taking.
As is always the case, do not adjust your dose unless your healthcare provider specifically instructs you to do so. People with poor kidney function may need lower azathioprine dosages. Also, a test can be done to see if you have low levels of thiopurine S-methyl transferase (TSMT), an enzyme that helps clear the drug from the body. If you have low TSMT levels, you will need a lower dose (or a different medication altogether) in order to prevent serious side effects.