Vectical - Scientific Information
|Form:||Cream, gel, liniment or balm, lotion, ointment, etc|
|Ingredients:||Calcitriol, Mineral Oil, dl-α-tocopherol, White Petrolatum|
VECTICAL (calcitriol) Ointment 3 mcg/g is a vitamin D analog intended for topical application to the skin. The chemical name of the active ingredient is (5Z,7E)-9,10-secocholesta-5,7,10(19)-triene-1α,3β,25-triol. The structural formula is:
Calcitriol is a white or almost white crystalline solid. It is practically insoluble in water, soluble in alcohol and in fatty oils. The molecular formula is C27H44O3, and the molecular weight is 416.64.
VECTICAL Ointment is a translucent ointment containing 3 mcg/g (0.0003% w/w) of calcitriol, packaged in aluminum tubes with screw caps. Other components of the ointment are mineral oil, dl-α-tocopherol, and white petrolatum.
The contribution to efficacy of individual components of the vehicle has not been established.
Mechanism of Action
The mechanism of action of calcitriol in the treatment of psoriasis has not been established.
The systemic exposure of calcitriol was assessed in subjects with chronic, plaque psoriasis. In the pivotal pharmacokinetic/pharmacodynamic study, calcitriol ointment 3 mcg/g, was applied twice daily for 21 days (for a total dose of 30 g/day) to 35% of the body surface area (psoriatic + surrounding healthy skin) of subjects with at least 25% of body surface area involvement. At Day 21, the geometric mean plasma concentration values of Cmax increased by approximately 36% over baseline and the geometric mean value of AUC(0 – 12 hr) increased by 44%. There was no correlation between the elevated calcitriol levels and the pharmacodynamic parameters of serum albumin adjusted calcium, serum phosphorus, urinary calcium and urinary phosphorus.
Carcinogenesis, Mutagenesis, Impairment of Fertility
When calcitriol was applied topically to mice for up to 24 months, no significant changes in tumor incidence were observed. Concentrations of calcitriol in ointment base of 0 (vehicle control), 0.3, 0.6 and 1.0 ppm were evaluated.
A two-year carcinogenicity study was conducted in which calcitriol was orally administered to rats at dosages of approximately 0.005, 0.03, and 0.1 mcg/kg/day (0.03, 0.18, and 0.6 mcg/m2/day, respectively). The incidence of benign pheochromocytomas was significantly increased in female rats. No other significant differences in tumor incidence data were observed.
In a study in which albino hairless mice were exposed to both ultra-violet radiation (UVR) and topically applied calcitriol ointment, a reduction in the time required for UVR to induce the formation of skin tumors was observed in all groups that received the ointment base, including the vehicle-treated control group, relative to animals that received no ointment but which were exposed to UVR. The time required for UVR to induce the formation of skin tumors did not differ between animals that received plain vehicle and those that received vehicle that contained calcitriol. Concentrations of calcitriol in ointment base of 0 (vehicle control), 0.3, 0.6 and 1.0 ppm were evaluated. These data suggest that the vehicle of VECTICAL Ointment may enhance the ability of UVR to induce skin tumors.
Calcitriol did not elicit genotoxic effects in the mouse lymphoma TK locus assay.
Studies in which male and female rats received oral doses of calcitriol of up to 0.6 mcg/kg/day (3.6 mcg/m2/day) indicated no impairment of fertility or general reproductive performance.
Based upon the recommended human dose and instructions for use, it is not possible to calculate human dose equivalents for animal exposure in these studies.
In two, multicenter, double- blind, vehicle-controlled studies, a total of 839 subjects with psoriasis rated "mild" or "moderate" using an investigator global assessment scale were treated twice daily for 8 weeks. Subjects were randomized in a 1:1 ratio to receive either VECTICAL Ointment or vehicle ointment. The mean age of the subjects was 48 years and 66% were male; most subjects were rated "moderate" at baseline.
Success was defined as "Clear or Minimal" (up to light red or pink in coloration, surface dryness with some white coloration, and slight elevation above normal skin) with at least a 2-grade change from baseline. The success rates are displayed in the table.
|Study 1||Study 2|
|Vectical Ointment (N=209)||Vehicle Ointment (N=209)||Vectical Ointment (N=210)||Vehicle Ointment (N=211)|