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.
High doses
of vitamin D often leads to hypercalcemia (high blood calcium levels)
which is characterized by nausea, vomiting, drowsiness, confusion, high
blood pressure, kidney failure, and coma. This was observed in the
Japanese study and can occur in those taking 1,000 lUs (international
units) or more of vitamin D.
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.
That was until researchers at Leo
Pharmaceutical Products in Denmark tried to develop a new form of
vitamin D which could clear up psoriatic plaques minus the risks
encountered in both oral and topical applications of cholecalciferol.
That led to the discovery of calcipotriol.
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
(which was tackled earlier in this series). 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 (both of which were discussed in this series) in treating
plaque-type psoriasis. Patients using the recommended dose of 50
micrograms per gram twice daily for six months have not developed
hypercalcemia, making calcipotriol safer than other conven¬tional
psoriasis regimens.
The long-term effects of calcipotriol,
however, are unknown and its safety in children and pregnant women has
not been established. Using more of the drug can also be dangerous. If
you go beyond the recommended dose and use more than 100 grams a week,
you may suffer from high blood calcium levels.
So far, the only
side effect reported is a mild skin irritation that occurs in 10 to 20
percent of patients who use calcipotriol. But this can be controlled by
means of careful application. Calcipotriol should not be used on the
face and patients are advised to wash away traces of the ointment that
accidentally get in other unaffected areas of the skin. If you
experience skin irritation, stop treatment and consult a doctor
immediately.
