Azathioprine hepatotoxicity is uncommon in patients with Rheumatic diseases

Area of Science:

• Rheumatology
• Hepatology
• Clinical Pharmacology

Background:

• Azathioprine (AZA) is a common Disease Modifying Antirheumatic Drug (DMARD) used in rheumatology.
• There is no established consensus on the necessity of routine liver enzyme monitoring during AZA treatment.
• Hepatotoxicity is a potential concern with AZA therapy.

Purpose of the Study:

• To evaluate the utility of routine liver enzyme monitoring (AST and AP) in rheumatology patients treated with azathioprine (AZA).
• To assess the incidence and clinical significance of liver enzyme elevations in patients on AZA.
• To inform guidelines regarding AZA monitoring protocols.

Main Methods:

• Retrospective review of 56 patient records from a DMARD clinic (1986-1996).
• Analysis of azathioprine dosage, duration, and co-administered DMARDs.
• Monitoring of serum aspartate aminotransferase (AST) and alkaline phosphatase (AP) levels.

Main Results:

• 41% of patients (23/56) had at least one abnormal AST or AP elevation while on AZA.
• Elevations typically occurred within 27 days of AZA initiation.
• 87% of abnormal liver enzyme values normalized spontaneously without intervention.
• No clinically significant adverse outcomes related to AZA hepatotoxicity were observed.

Conclusions:

• Azathioprine use in rheumatic conditions may cause transient elevations in AST and/or AP.
• These liver enzyme elevations were generally not clinically significant in this patient cohort.
• The findings support current guidelines against routine liver enzyme monitoring for RA patients on AZA.
• The value of baseline liver enzyme testing prior to AZA initiation is questionable.