[A toxicological study of etretinate and its effect on blood and tissue (author's transl)]

10 mg/kg of etretinate was administrated orally for 4 weeks to a Sprague-Dawley rat (male, approx. 140 g in weight) and its toxicity was checked at 2 and 4 weeks after the start of administration. Recovery was checked 2 and 4 weeks after end of administration. Three weeks after administration of etretinate, a decline in the increase of body weight and a decline in movement due to abnormality in the lower half of the body was seen. Two weeks after administration, the thigh bone was observed to thin and to have fragility; 4 weeks after administration the changes in the thigh bone became more eminent and the forearm was seen to thin 4 weeks after administration of etretinate, the hematological test showed an increase of leukocytes and the biochemical test showed an increase of triglycerides and phospholipids. The calcium in the thigh bone showed a notable decrease 2 and 4 weeks after administration. The decline in the increase of body weight; the increase of leukocytes, triglycerides and phospholipids; and the decrease of calcium in the thigh bone recovered to normal 2 weeks after the end of administration. Blood retinol decreased and a decrease in retinyl palmitate and retinol in the liver was induced by the administration of etretinate. The toxicity of etretinate was seen to be comparatively lower than that of retinoid. A more detailed study is thought to be needed concerning the changes in bone.