A one-year, open, prospective study of sulfasalazine in the treatment of rheumatoid arthritis: adverse reactions and clinical response in relation to laboratory variables, drug and metabolite serum levels, and acetylator status.

Response to sulfasalazine was studied for 1 year in 45 patients with rheumatoid arthritis. Twenty-two patients achieved a satisfactory clinical response. Adverse reactions developed in 15. Hemoglobin rose, and platelet count, erythrocyte sedimentation rate, rheumatoid factor titer, immunoglobulins, and C3 component of complement fell in relation to degree of response. At 1 year, 18 patients elected to continue the treatment. No relationship between clinical response, adverse reactions, or laboratory changes and drug disposition was observed.