Combination of Topical Calcipotriol (MC 903) and UVB Radiation for Psoriasis vulgaris

Abstract

The synthetic compound MC 903 (calcipotriol) is a structural analogue of the naturally occurring, biologically active 1,25-dihydroxyvitamin D3 [1,25-(OH)2-D3]. MC 903 and 1,25-(OH)2-D3 show similar receptor binding and comparable effects on cell differentiation. However, MC 903 appears to be at least 100 times less potent in its effects on calcium metabolism. In previous double-blind placebo-controlled studies, topical MC 903 has been shown to have a therapeutic effect in psoriasis. The present open study involving 20 patients with psoriasis vulgaris was a right/left comparison of the efficacy and tolerability of MC 903 ointment (50 micrograms/g) alone or with UVB radiation. After treatment for 8 weeks, topical MC 903 alone resulted in marked improvement in 66% of the patients and in clearance in 17%. Combination of topical MC 903 with UVB resulted in marked improvement in 50% of the patients and in clearance in 39%. These differences were not statistically significant. No significant change in serum calcium levels was detected. Two patients developed a facial dermatitis which disappeared spontaneously during continued treatment. These results show that the combination of topical MC 903 and UVB radiation is well tolerated. Larger-scale studies are warranted to answer the question whether UVB radiation induces a significant improvement of the antipsoriatic effect of topical MC 903.