A 52-week oral chronic toxicity study of 6-amidino-2-naphthyl 4-[(4,5-dihydro-1H-imidazol-2-yl)amino] benzoate dimethanesulfonate (FUT-187) in rats with a recovery period of 5 weeks.

Abstract

The chronic toxicity of FUT-187, a synthetic protease inhibitor, was investigated in Sprague-Dawley rats. FUT-187 was given orally to the rats at doses of 0.4, 2, 10, 50 and 250 mg/kg/day for 52 weeks. The drug was then withdrawn for 5 weeks. The results are summarized as follows: There were no deaths or toxic signs caused by the drug throughout the experimental period. There were no drug-related changes in food consumption, ophthalmological examination, hematology or blood chemistry. Slight suppression of growth was observed in males in the 250 mg/kg group. This change was reversed on withdrawal of the drug. Drug crystals were observed in the urinary sediments of both sexes in the 250 mg/kg group, but this change disappeared on withdrawal of the drug. Gross pathological examination revealed the following changes: enlargement and nodule formation in the pancreas in both sexes given more than 10 mg/kg of the drug; dark red spots in the glandular stomach in males in the 250 mg/kg group; thickening of the small intestinal walls in both sexes given more than 50 mg/kg. Of these organs, no changes were observed in the stomach and small intestine at the end of the recovery period. Increased pancreas weight was observed in both sexes given more than 50 mg/kg of the drug. Examination at the end of the recovery period suggested reversibility, showing a lesser degree of change. Histopathological examination revealed the following changes in the pancreatic acinar cells: acidophilic foci and nodules in both sexes given more than 10 mg/kg of the drug; adenoma in one male in the 250 mg/kg group; increased zymogen granules in both sexes given more than 50 mg/kg of drug; fine vacuolization in females in the 250 mg/kg group. At the end of the recovery period, increased zymogen granules and fine vacuolization of the acinar cells were not found. Furthermore, erosion or healed erosion in the glandular stomach, duodenum and jejunum was observed in a few males or females in the 250 mg/kg group, but those changes disappeared after the recovery period. In the liver, altered cell foci was observed more frequently in males in the 250 mg/kg group than the other groups, but this change also disappeared after the recovery period. In addition, brown pigmentation in the proximal renal tubules of the kidney was observed in both sexes in the 250 mg/kg group, but lesions observed in the examination after the recovery period were less noticeable than in the examination at the end of the administration period.