Oral doses of vitamin D have been considered as a treatment for psoriasis. This was sparked by experiments with cholecalciferol or 1,25 dihydroxyvitamin D3 (1,25 (OH)2D3), the active form of vitamin D made in the kidney, which showed promise in treating widespread psoriasis.
Using a one microgram daily dose of cholecalciferol, Japanese researchers in 1986 managed to treat 13 out of 17 psoriatic patents within three months. But there are risks involved with this therapy.
The topical use of cholecalciferol by the same researchers proved to be more beneficial and less toxic. Sixteen out of 19 patients were treated within three weeks with a dose of 0.5 microgram per gram compared to three months with oral doses. Still, the possibility of hypercalcemia remained since vitamin D is absorbed by the skin.
Calcipotriol is a vitamin D3 derivative which is just as effective as cholecalciferol in controlling rapid cell growth in psoriatic skin yet 100 - 200 times less likely to produce hypercalcemia. Unlike other creams and ointments, it is colorless and odorless and generally well-tolerated by patients.
This vitamin D3 analogue is recommended for the treatment of plaque-type psoriasis and can be used alone or in combination with UVB radiation. The exact mechanism of calcipotriol is unknown but numerous studies have established the efficacy of this drug.
Controlled clinical trials have shown that calcipotriol is just as effective as some steroids and more effective than anthranol.Patients using the recommended dose of 50 micrograms per gram twice daily for six months have not developed hypercalcemia, making calcipotriol safer than other conventional psoriasis regimens.
