Parenteral high dose methotrexate and sulfasalazine are the only two agents with well demonstrated published efficacy in psoriatic arthritis. The magnitude of the effect seen with azathioprine, etretinate, oral low dose methotrexate and perhaps colchicine suggests that they may be effective but that further multicentre clinical trials are required to establish their efficacy. Furthermore, the magnitude of the improvement observed in the placebo group strongly suggests that uncontrolled trials should not be used to guide management decisions in this condition.
Sulfasalazine therapy for psoriatic arthritis: a double blind, placebo controlled trial.
Psoriatic arthritis (PsA) is often poorly responsive to 2nd line antirheumatic drug therapy. Sulfasalazine has recently gained wide acceptance in the treatment of rheumatoid arthritis, and beneficial effects have also been noted in ankylosing spondylitis and reactive arthritis. We report a double blind placebo controlled study of sulfasalazine in PsA.
                Twenty-four patients with active PsA were randomized to receive either sulfasalazine (3 g/day) (n = 10) or placebo (n = 14) for 8 weeks, in a double blind manner, followed by an 8 week open label crossover phase for nonresponding placebo patients.
                Compared with placebo controls, sulfasalazine treated patients were significantly improved at Weeks 4 and 8 with respect to physician (p < 0.01) and patient (p < 0.05) global assessments. Duration of morning stiffness was significantly decreased at Week 8 (p < 0.01). Clinical variables of disease activity returned to baseline after a 4 week drug washout period in 5 evaluable patients. Six patients in the placebo group crossed over to an 8 week open label phase and demonstrated significant improvements in joint scores, 50 ft walking time, and global patient assessment. Sulfasalazine treated patients also showed significant improvements in cutaneous involvement.
                Sulfasalazine was effective in PsA, with efficacy observed as early as the 4th week of treatment. Longterm studies are needed to determine whether such therapy can modify disease outcome.