TOPICALLY APPLIED LOW-DOSE CALCITRIOL HAS NO CALCIOTROPIC EFFECT IN PATIENTS WITH STABLE PLAQUE PSORIASIS

Background: Topical calcitriol, a potent inhibitor of cell proliferati on and inducer of terminal cell differentation, can clear psoriasis. H owever, possible side effects on calcium and bone metabolism from tran sdermal absorption have not been evaluated. Objective: The calciotropi c effects of low-dose calcitriol (3 mu g/gm) ointment, applied twice d aily for 6 weeks, were investigated. Methods: A double-blind study was carried out in 18 patients with chronic stable plaque-type psoriasis, of whom nine were treated with calcitriol (3 mu g/gm) and nine with b etamethasone dipropionate (500 mu g/gm). The main end points were calc itriol plasma concentrations, intestinal calcium absorption, and bone turnover. Results: Serum alkaline phosphatase concentrations increased slightly (p < 0.02) and intestinal calcium absorption decreased sligh tly (p < 0.01) in the calcitriol-treated group. However, the alteratio ns were too small to have any clinical relevance. Conclusion: Low-dose calcitriol, topically applied for 6 weeks on a maximal body surface a rea of 30%, can be considered as safe regarding calcium and bone metab olism.