[Immunosuppressive agents in Horton's disease. Which drug for which indication?]

Corticosteroids remain the cornerstone treatment of giant cell arteritis. Steroid-related toxicity and needs for alternative therapeutic regimens in patients experiencing recurrent active or steroid-resistant diseases, are the main reasons for searching a steroid-sparing agent. Regarding disease pathogenesis, immunosuppressive agents might be useful drugs. Methotrexate is the most widely studied agent in this indication. However, available data are incomplete and studies have included only polymyalgia rheumatica or both polymyalgia rheumatica and giant cell arteritis affected patients. Results of these studies evoke the possibility of using methotrexate in steroid-dependent or resistant diseases, as well as a steroid-sparing agent in order to taper off and stop steroids quickly; with an acceptable toxicity. Azathioprine may be used to control steroid-dependant or resistant diseases, but toxicity appears to be higher. An open prospective study compared azathioprine and methotrexate and concluded to the superiority of methotrexate. Available data concerning cyclophosphamide and cyclosporine A are too incomplete. A satisfactory steroid-sparing agent in giant cell arteritis is still unknown. Currently, methotrexate, and probably azathioprine, appear to be the most useful agents in this indication. However, there is no demonstration that using an immunosuppressive agent in giant cell arteritis could reduce steroid-related morbidity.