To evaluate the efficacy and the tolerance of sulfasalazine in the treatment of chronic lupus erythematosus (CLE).

We prescribed sulfasalazine (2 g/d) for 18 patients with severe CLE, all of whom had contraindications for or treatment failure with antimalarial drugs and thalidomide. This study analyses their response to treatment, duration of therapy, reasons for stopping, adverse effects, and the influence of the N-acetyltransferase 2 (NAT2) phenotype.

We observed 10 complete and 3 partial responses, and 4 patients maintained complete response for at least 7 years. Eight patients experienced adverse effects, and 2 needed to stop treatment (because of photosensitization and development of antinuclear antibodies). All side effects occurred in the first 3 months of treatment. None of the 18 patients developed systemic lupus erythematosus. Of the 10 complete responders, 9 were rapid acetylators (RA), while 4 of the 5 who failed to respond were slow acetylators (SA). Leukopenia and photosensitization were observed in SA patients, while different side effects occurred in RA patients (headaches, diarrhea, moderate increase in liver enzymes and antinuclear antibodies).

These findings confirm our earlier reports and demonstrate that sulfasalazine can be used successfully to treat severe CLE. NAT2 genotyping before initiating treatment helps to identify potential responders and avoid side effects. In RA patients, sulfasalazine can be an alternative to thalidomide after antimalarial drugs, whereas in SA patients, it should remain a third-line treatment, to be used only after antimalarials and thalidomide.