Placebo response in two long-term randomized psoriasis studies that were negative for rosiglitazone.

Background: Previous research has suggested that the thiazolidinedione rosiglitazone may possess anti-psoriatic activity.

Objective: To compare the efficacy and safety of rosiglitazone with that of placebo in the treatment of chronic plaque psoriasis.

Methods: Two large-scale, randomized, double-blind, multicenter studies (study A, n = 1563; study B, n = 1032) were conducted over 52 weeks (plus optional 44 weeks safety extension) in an outpatient setting.