[A 26-week repeated percutaneous dose toxicity study of calcipotriol (MC903) in dogs]

A 26-week repeated percutaneous dose toxicity of calcipotriol (MC903), an anti-psoriasic agent, was studied in beagle dogs at doses of 0.04, 0.4 and 4 micrograms/kg/day. 1. In general conditions, reddening, rash, desquamation, pruritus, wet and hot skin at 4 micrograms/kg/day, reddening, rash and desquamation at 0.4 microgram/kg/day, pruritus and desquamation at 0.04 microgram/kg/day, were observed at the skin of application site. 2. In urinalysis, an increase or a tendency to an increase in Ca level, were observed at 4 micrograms/kg/day. 3. Histopathological examinations revealed squamous cell hyperplasia and parakeratosis at the skin of application site in both sexes at 4 micrograms/kg/day. However, these findings were not shown at the skin of application site at 0.4 and 0.04 microgram/kg/day. 4. On the basis of results obtained in the present study, it is considered that 0.4 microgram/kg/day is the no-toxic dose of MC903 applied percutaneously in both sexes of beagle dogs.