The effect of 1,24(R)(OH)2D3 cream and ointment on epidermal proliferation and differentiation in mice.

The 1,24(R)(OH)2D3 (tacalcitol) ointment (2 micrograms/g) is available commercially as an antipsoriatic drug in Japan, but the cream preparation of tacalcitol is still under development. This study was conducted to compare the ability of tacalcitol cream and ointment to inhibit epidermal proliferation and induce epidermal differentiation. We measured the ornithine decarboxylase activity and type I transglutaminase activity as indices of proliferation and differentiation, respectively, in hairless mice. These effects were statistically equal to those of the ointment preparation at the same dose, 2 micrograms/g, without inducing hypercalcemia. These findings suggest that topical application of 1,24(OH)2D3 cream (2 micrograms/g) might have the same potency as the ointment formulation in the treatment of psoriasis.