A 26-week repeated subcutaneous dose toxicity study of calcipotriol (MC903) followed by a 5-week recovery test in rats

Abstract

A 26-week repeated subcutaneous dose toxicity of calcipotriol (MC903), an anti-psoriasic agent, followed by a recovery for 5 weeks was studied in Slc:SD rats at doses of 0.4, 2 and 10 micrograms/kg/day as low, mid and high dose levels. 1. No mortality during the experimental period was observed in both sexes of all groups including control. An increased incidence of opacity of the eyeball surface in males was noted at high dose. There were no difference in body weight and food consumption between control. An increased water consumption in both sexes was observed at high dose. 2. An increased incidence of the corneal opacity was noted significantly at high dose in both sexes compared with that observed in control. Urinalysis revealed the increased excretions of Ca at more than mid dose, and Na, Cl and IP in males at high dose, and an decreased urinary volume in females and lower pH in both sexes at high dose. An increased serum Ca level in males at mid dose and in both sexes at high dose, and an elevated ALP activity in males at high dose were observed. The increased weights of the kidney in males at more than mid dose and adrenal gland in both sexes at high dose were observed. The increased incidence of mineralization of the cornea and kidney was noted significantly in males at more than mid dose as compared with control. Dilatation of endoplasmic reticulum of distal tubular cells of the kidney in both sexes was observed at high dose on electron microscopic examination. 3. After a 5-week recovery period, the changes related with the treatment of MC903 almost disappeared except for mineralizations of the cornea and kidney. 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 administered subcutaneously in both sexes of rats.