Topically applied low-dose calcitriol has no calciotropic effect in patients with stable plaque psoriasis.

Abstract

Topical calcitriol, a potent inhibitor of cell proliferation and inducer of terminal cell differentiation, can clear psoriasis. However, possible side effects on calcium and bone metabolism from transdermal absorption have not been evaluated. The calciotropic effects of low-dose calcitriol (3 micrograms/gm) ointment, applied twice daily for 6 weeks, were investigated. A double-blind study was carried out in 18 patients with chronic stable plaque-type psoriasis, of whom nine were treated with calcitriol (3 micrograms/gm) and nine with betamethasone dipropionate (500 micrograms/gm). The main end points were calcitriol plasma concentrations, intestinal calcium absorption, and bone turnover. Serum alkaline phosphatase concentrations increased slightly (p < 0.02) and intestinal calcium absorption decreased slightly (p < 0.01) in the calcitriol-treated group. However, the alterations were too small to have any clinical relevance. Low-dose calcitriol, topically applied for 6 weeks on a maximal body surface area of 30%, can be considered as safe regarding calcium and bone metabolism.