Influence of acetylator status on sulphasalazine efficacy and toxicity in patients with rheumatoid arthritis.

The influence of acetylator status on the therapeutic efficacy and the toxicity of sulphasalazine (SASP) was assessed in 106 patients with rheumatoid arthritis (RA). Changes of indices of disease activity after 6 months, and progression of erosions after 2 years of SASP treatment were similar in fast and slow acetylators. Incidence and nature of withdrawals and side-effects, and requirement for intra-articular steroid injections or combination therapy due to poor response to SASP were almost identical in the two groups. A significant increase of the hepatic enzyme aspartate transaminase was noted mainly in slow acetylators, but was not associated with clinical disease. These results suggest that acetylator status does not relate significantly to either the efficacy or the toxicity of SASP in RA. It is possible that hepatic metabolism is affected by SASP, particularly in slow acetylators, but this does not lead to clinically identifiable problems.