Treatment of Psoriasis by the Topical Application of the Novel Cholecalciferol Analogue Calcipotriol (MC 903)

Abstract

Calcipotriol (the synthetic compound MC 903) is a structural analogue of naturally occurring, biologically active calcitriol. Calcipotriol and calcitriol (1,25-dihydroxy vitamin D3) show similar receptor binding and comparable effects on cell differentiation. However, calcipotriol seems to be at least 100 times less potent in its effects on calcium metabolism. In a double-masked study involving 50 patients with psoriasis vulgaris, the efficacy and tolerability of ointments containing various calcipotriol concentrations (25, 50, or 100 micrograms/g) or the vehicle alone were compared in a study involving a right-left, within-patient randomized design. Patients were treated twice daily for 8 weeks. Marked improvement was seen in 40% of the patients treated with the 25-micrograms/g concentration of calcipotriol in 63% of patients treated with the 50-micrograms/g concentration, and in 88% treated with the 100-micrograms/g concentration. No patient treated with placebo had more than slight improvement. Five patients developed facial dermatitis during the study. The serum levels of ionized calcium were unchanged. This study demonstrates that calcipotriol ointment provides an effective and well-tolerated treatment of psoriasis vulgaris.