The effects of topical prophylthiouracyl in plaque type psoriasis: A prospective, double-blind, placebo-controlled study

Background and Design: Propylthiouracil (PTU) decreases the synthesis of thyroid hormon as well as having immune modulatory and free radical scavenging effects. Oral PTU has been shown to be effective for the treatment of plaque psoriasis in several studies. This study was performed to determine the efficacy of topical PTU in psoriasis. Materials and Methods: Different plaques of 16 patients with plaque psoriasis were treated with 5% topical PTU and placebo, three times daily for 8 weeks in a setting of a double-blind and placebo controlled study. Response to therapy was evaluated by using clinical score, histopathologic score and epidermal thickness. Results: The clinical scores of both PTU and placebo plaques decreased significantly after the treatment (p<0.001). The epidermal thickness of the psoriatic PTU plaques before and after treatment were 0.57 +/- 0.1 mm and 0.46 +/- 0.19 mm, respectively. Furthermore, no significant difference was observed between the pre- and post-treatment histopathological findings of plaques treated with PTU. Conclusion: Topical PTU may be viable steroid-sparing agent, since topical corticosteroid as a conventional agent, have many side effects. Since we didn't observe a significant difference between the plaques treated with PTU and placebo in our group, we concluded that further studies with larger series should be performed to confirm this hypothesis.