Immunosuppressive drugs: Azathioprine

Author: V. Dimov, M.D., Allergist/Immunologist at Cleveland Clinic
Reviewer: S. Randhawa, M.D., Allergist/Immunologist and Assistant Professor at LSU (Shreveport) Department of Allergy and Immunology

(This article is based in large part on Wikipedia articles that were reviewed for accuracy, please see the reference links).

Azathioprine is an immunosuppressant pro-drug, converted in the body to the active metabolites 6-mercaptopurine and 6-thioinosinic acid. It is a purine synthesis inhibitor. Azathioprine is available in oral form.

Azathioprine. Image source: Wikipedia, public domain.

For many years, dual therapy with azathioprine and steroids was the standard anti-rejection regimen, until cyclosporine was introduced into clinical practice in 1978.

Azathioprine is a purine synthesis inhibitor, inhibiting the proliferation of cells, especially leukocytes. Azathioprine suppresses the bone marrow and CBC should be monitored. Caution should be exercised when it is used in conjunction with purine analogues such as allopurinol.

Metabolic pathway for azathioprine. Image source: Wikipedia, GNU Free Documentation License.

Azathioprine may be used in severe atopic dermatitis. It has a slow onset of action and needs a trial for several months to see an improvement.

Mycophenolate (CellCept) - an alternative to azathioprine

Mycophenolic acid. Image source: Wikipedia, public domain.

Mycophenolate mofetil is increasingly being used in place of azathioprine in organ transplantation, as it is associated with less bone marrow suppression, fewer opportunistic infections, and a lower incidence of acute rejection.

Mycophenolic acid is commonly marketed under the trade names CellCept (mycophenolate mofetil; Roche) and Myfortic (mycophenolate sodium; Novartis).

Mycophenolate is derived from the fungus Penicillium stoloniferum.

Mycophenolate blocks lymphocyte proliferation by inhibiting guanine nucleotide synthesis in lymphocytes.

What is the molecule that tacrolimus binds to in order to exert its therapeutic effect?

(A) NFkB
(B) calcium
(C) ipraimmunophilin
(E) calcineurin
(F) calmodulin
(G) AP-1

Answer: E.


Immunosuppressive drugs. Wikipedia.
Abbas' Immunology, edition 6, 2009.
Azathioprine. Wikipedia.
Mycophenolic acid. Wikipedia.

Published: 05/20/2009
Updated: 08/20/2014

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