An update on vitamin D3 analogues in the treatment of psoriasis.

Vitamin D3 analogues have revolutionized the topical treatment of psoriasis during the last decade. The mode of action of this ligand for the vitamin D3 receptor is via modulation of the transcription of genes with vitamin D3 response elements in their promoter region. Vitamin D3 analogues cause inhibition of various aspects of cutaneous inflammation and epidermal proliferation with enhancement of normal keratinization. In vivo, active vitamin D3 analogues proved to have a substantial antipsoriatic effect. Calcipotriol (50 micrograms/g in ointment or cream), tacalcitol (4 micrograms/g in ointment) and calcitriol (3 micrograms/g in ointment) have been shown to have an antipsoriatic effect in placebo-controlled studies. The most extensive body of information on comparative studies and on combination therapies is available for the analogue calcipotriol. So far, calcipotriol is available as a routine treatment in most countries, whereas tacalcitol has been registered in Japan and some European countries. From the available data in the literature we may conclude that calcipotriol is a first-line treatment for psoriasis and is advantageous in the combination with several other antipsoriatic treatments such as topical corticosteroids, PUVA, cyclosporin and acitretin. Tacalcitol 4 micrograms/g as a once-daily principle is effective in psoriasis. Comparative studies will indicate the position of the existing and new vitamin D3 analogues.