It has been shown that la, 25-dihydroxycholecalciferol (1) lJ or its analogs [1a- hydroxycholecalciferol, 2a la, 24-dihydroxycholecalciferol, 3 calcipotriol I have beneficial therapeutic effects in psoriasis, a hyperproliferative skin di~ order.~ However, their clinical use may be limited by