[Role of dapsone in the treatment of Horton's disease and polymyalgia rheumatica].

The authors report 8 cases of Horton's disease and/or polymyalgia rheumatica treated with prednisone with an initially favourable result. However, the disease progressed despite relatively high dose steroid therapy, complications of which contraindicated increasing the dosage and even necessitated rapid withdrawal of steroids. The association of dapsone 100 mg/day orally had a rapid favourable effect in all 8 cases. However this treatment was well tolerated in only 3 patients and could only be continued in 4 out of the 8 cases. Manifestations of intolerance (methemoglobinaemia) rapidly regressed after withdrawal of dapsone but this was followed by another exacerbation of the disease, resulting in a therapeutic impasse. Despite the incidence of these iatrogenic complications, dapsone would appear to provide a therapeutic option in patients with Horton's disease and/or polymyalgia rheumatica resistant to high dose steroid therapy or in whom complications of steroid therapy impose a reduction in dosage or complete withdrawal of the drug.