Which statement about Azathioprine is NOT accurate?

• A. Weekly administration
• B. Side effect: Cytopenia
• C. Simultaneous administration of allopurinol can fourfold its effect
• D. Relatively safe in pregnancy

Answer: (D)

Azathioprine is a purine analog used for immunosuppression, and its effects and risks are driven by how it is metabolized and how it interacts with other drugs. It is normally given daily to maintain steady immunosuppression, not weekly, so the idea of weekly administration isn’t consistent with standard practice.

Bone marrow suppression is a well-known adverse effect, so cytopenias are a real risk and require regular blood count monitoring.

A key drug interaction is with allopurinol: inhibiting xanthine oxidase slows the metabolism of azathioprine, allowing more active metabolites to accumulate. This can markedly increase toxicity, sometimes described as a several-fold rise in effect, which is why coadministration needs a substantial dose reduction and close monitoring.

Regarding pregnancy, azathioprine is not simply “relatively safe.” While it is used in pregnancy when benefits outweigh risks, it is categorized as a pregnancy risk (and carries fetal risk) and is not considered universally safe. Its use in pregnancy requires careful assessment and monitoring.

So the statement that is not accurate is the notion that azathioprine is relatively safe in pregnancy. The other points—nonweekly dosing, risk of cytopenias, and significant interaction with allopurinol—fit with how the drug is commonly understood and managed.