Patients being started on azathioprine should be informed of the necessity of periodic blood counts while they are receiving the drug and should be encouraged to report any unusual bleeding or bruising to their physician. They should be informed of the danger of infection while receiving azathioprine and encouraged to report signs and symptoms of infection to their physician. Careful dosage instructions should be given to the patient, especially when azathioprine is being administered in the presence of impaired renal function or concomitantly with allopurinol. Patients should be advised of the potential risks of the use of azathioprine during pregnancy and during the nursing period. The increased risk of neoplasia following azathioprine therapy should be explained to the patient.
Use with Allopurinol: The principal pathway for detoxification of azathioprine is inhibited by allopurinol. Patients receiving azathioprine and allopurinol concomitantly should have a dose reduction of azathioprine, to approximately 1/3 to 1/4 the usual dose.
Use with Other Agents Affecting Myelopoesis: Drugs which may affect leukocyte production, including co-trimoxazole, may lead to exaggerated leukopenia, especially in renal transplant recipients.
Use with Angiotensln Converting Enzyme Inhibitors: The use of angiotensin converting enzyme inhibitors to control hypertension in patients on azathioprine has been reported to induce severe leukopenia.
Azathioprine should not be given to patients who have shown hypersensitivity to the drug.
Azathioprine should not be used to treat rheumatoid arthritis in pregnant women. Patients with rheumatoid arthritis previously treated with alkylating agents (cyclophosphamide, chlorambucil, melphalan or others) may have a prohibitive risk of neoplasia if treated with azathioprine.