Calcipotriol: a new drug for topical psoriasis treatment.

Vitamin D is best known for its role in the regulation of calcium and bone metabolism. The effects of the biologically active form of vitamin D, 1,25-dihydroxyvitamin D3 (1,25 (OH)2D3), are mediated by binding to a specific intracellular vitamin D receptor, which is present in most tissues including the skin where it regulates the growth of epidermal cells. Calcipotriol is a synthetic analogue of 1,25(OH)2D3. In vitro the activity of calcipotriol is comparable to that of 1,25(OH)2D3. In vivo, however, the risk of calcipotriol changing calcium metabolism is greatly reduced. Animal studies have established that calcipotriol is 100-200 times less calcaemic than 1,25(OH)2-D3. This low calcaemic activity is mainly due to the rapid metabolism of calcipotriol. This pharmacological profile makes calcipotriol an ideal candidate for topical treatment of hyperproliferative skin disorders, such as psoriasis. This paper reviews the clinical experience with calcipotriol in psoriasis patients.