[Fifty two-week chronic oral toxicity study of mofezolac (N-22) in beagle dogs]

The chronic toxicity study of mofezolac (N-22), a new developed analgesic and anti-inflammatory agent, was carried out in beagle dogs by oral administration of the test compound at dose levels of 1, 3, 6 and 12 mg/kg once daily for 52 weeks. The recovery study was also carried out by withdrawal for 5 weeks. 1. No death occurred during the administration and recovery periods in all groups, there were no abnormal findings due to N-22 administration on behavior and appearance, body weight and food consumption. 2. There were no abnormal findings due to N-22 administration on fecal test, urinalyses, hematological and biochemical examinations, hepatic and renal function tests, ophthalmological examination, electrocardiography, blood pressure and organ weight. 3. By histopathological examination, loss of villi in small intestine was found in one female of 6 mg/kg group, erosion in small intestine in one male of 12 mg/kg group, and shortening of villi and ulcer in small intestine in each one female of 12 mg/kg 4. Accordingly, the non-effective dose levels of N-22 were estimated to be 6 mg/kg for male and 3 mg/kg for female in this study.