Combination therapy and MTX alone are superior to AZA monotherapy in active RA, but there is no statistically significant difference in their effect on outcome assessment (Willkens RF et al. 1992). The major concern of AZA is immunosuppression and the bone marrow toxicity. The incidence of infections and drug withdrawal, secondary to adverse event, is higher for AZA than MTX (Suarez- Almazor ME et al. 2000). The long-term sustainability of the drug is
lesser than MTX (Kerstens PJ et al. 2000). Due to these disadvantages, the drug is less commonly used than other DMARDs.

REFERENCES
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2. Suarez-Almazor ME, Spooner C, Belseck E. Azathioprine for treating rheumatoid arthritis. Cochrane Database Syst Rev. 2000(4):CD001461.
3. Kerstens PJ, Boerbooms AM, Jeurissen ME, de Graaf R, Mulder J, van de Putte LB. Radiological and clinical results of longterm treatment of rheumatoid
arthritis with methotrexate and azathioprine. J Rheumatol. 2000;27(5):1148-55.