Trandolapril (RU44570) was orally administered to dogs at a daily dose of 2.5, 25 or 250 mg/kg for 13 weeks. After the administration period, 25 and 250 mg/kg groups were observed for recovery for 4 weeks. The results obtained are as follows: 1. One male in the 250 mg/kg group showed decrease of food consumption and body weight, stomatitis, hematemesis, decumbence, hypothermia, and finally loss of reactivity to stimuli. This animal was killed because of these severe changes on the 39th day of administration. Among the surviving animals, a temporary loss of body weight was observed in a few animals of the 25 and 250 mg/kg groups, and a decreased food consumption was sporadically seen in a few animals of the 250 mg/kg group during the administration period. No abnormal changes were found in the clinical observation and water intake in the surviving animals. 2. The changes attributable to the pharmacological effect of RU44570 were a decreased activity of the angiotensin-converting enzyme, increases in plasma renin activity and urine volume, and decreases in specific gravity and concentrations of Na, K and Cl in the urine of every administration group. A decrease in blood pressure and an increase in the PAS and Bowie positive granules in the juxtaglomerulat cells were also found in the 25 and 250 mg/kg groups. In addition, thickening of the afferent arteriolar wall of the glomeruli, a basophilic change of the renal tubular epithelial cells, and localized atrophy and hypertrophy of the renal tubules were observed in the 25 and 250 mg/kg groups, and increases in BUN, ALP and creatinine, and a slight dilation of the renal tubules were seen in the 250 mg/kg group. These observations indicated that RU44570 affected renal structure at a dose of 25 mg/kg or more renal function at a dose of 250 mg/kg. The animal killed in a moribund state showed nephrosis which consisted mainly of a moderate dilation of the fenal tubules and vacuolation of the renal tubular epithelial tells, stomatitis, severe hemorrhage and necrosis with neutrophil infiltration in the fundus of the glandular stomach, atrophy of the hemopoietic system, and ectopic calcification in the heart, kidneys, stomach, trachea and alveolar wall. Changes in the kidneys similar to those observed in other animals were also detected. These changes suggested that this animal lapsed into a moribund state due to renal dysfunction and the resultant uremia. 3. Decreases in the RBC, Ht and Hb were observed in the 25 and 250 mg/kg groups. Histologically, an increase in Kupffer's cells that ingested hemosiderin in the liver and increased hemosiderin deposition in the red pulp of the spleen were found in these groups. Hence, a hemolytic anemia was surmised in the 25 and 250 mg/kg groups. However, no changes were found in the myelogram or no compensatory reactions such as increased extramedullary hemopoiesis were detected. 4. After the recovery period, 1 female showed decreases in the RBC, Ht and Hb, and another female showed decreased blood pressure in the 250 mg/kg group. In addition, increased granules in the juxtaglomerular cells and thickening of the glomerular afferent arteriolar wall were found in the 25 and 250 mg/kg groups. However, these changes were less intense than those observed after the administration period. Other changes observed at the end of the administration period were no longer detected after the recovery period. In conclusion, the no-adverse-effect level of RU44570 for beagles was 2.5 mg/kg in this 13 week oral toxicity study. At the dose of 25 mg/kg or more, effects on the erythrocyte system and kidneys were observed. However, the effects were reversible and most of the changes disappeared after a 4 week recovery period.

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The chronic toxicity of (-)-(2S, 3aR, 7aS)-1-[(S)-N-[(S)-1-ethoxycarbonyl-3-phenylpropyl]alanyl]hexahydro-2-indolinecarboxylic acid (trandolapril: RU44570), a novel angiotensin-converting enzyme blocking antihypertensive drug, was assessed in rats by oral administration for 12 months at dosage levels of 0.05, 0.25, 2.50 and 25.00 mg/kg/day, comparing with the control animals received 0.5% methylcellulose solution. Reversibility of the drug-induced changes was also examined by 3 months' withdrawal following the administration period. 2) There was no death or general symptom that was thought to be attributable to the administration of RU44570. 3) The body weight gain was significantly suppressed from 1st week to the end of administration period in male animals of the dosage groups of 2.50 mg/kg or more and from week 1 to 15 of administration in female animals of the 25.00 mg/kg dosage group. During the withdrawal period, the difference of the body weights between these groups and control was reduced and that was never statistically significant. 4) The food consumption generally tended to be lowered in male animals of the dosage groups of 2.50 mg/kg or more throughout the administration period. The values were significantly different from that of control group on almost all measurement points from week 2 to 34 of administration. The difference of the food consumption of these groups from control group tended to be smaller thereafter, although significant difference was seen sporadically. Male animals of the 0.05 and 0.25 mg/kg dosage groups also showed the tendency of decreased food consumption infrequently. There was no constant tendency of fluctuation in the food consumption among the each RU44570 treated group during the withdrawal period. 5) The water consumption increased significantly in male animals of the 25.00 mg/kg dosage group from 1st week to the end of administration period. Male animals of the 2.50 mg/kg dosage group showed similar high value of the water consumption but the degree was lesser than that of 25.00 mg/kg dosage group. Although female animals of the 25.00 mg/kg dosage group showed significantly increased water consumption from week 3 to 4 of administration, they began to show decreasing tendency from approximately week 10 of administration conversely. From week 26 of administration, the water consumption of this group significantly decreased frequently comparing with that of control group. Female animals of the 2.50 mg/kg dosage group showed similar decrease in water consumption from approximately week 26 of administration. The value of water consumption was still high in male animals of the 25.00 mg/kg dosage group during the withdrawal period, however, reached to the level of control at week 13 of withdrawal after gradual remission. Female animals of the 0.05 mg/kg dosage group showed significant and remarkable high value in water consumption at week 1 of withdrawal. The water consumption of this group tended to increase thereafter, but the difference from that of control group was not significant. The fluctuations of water consumption in other treated groups was not observed during the withdrawal period. 6) No significant change that was thought to be attributable to the administration of RU44570 was detected by the ophthalmological examination. 7) Urinalysis revealed increased urine volume, high value of pH and the changes associated with diluted urine in male animals of the dosage groups of 0.05 mg/kg or more, i. e., lower content or value in electrolytes, bilirubine, ketone body, protein, urobilinogen, occult blood, specific gravity and number of cells in the sediment. These changes were not observed at the end of withdrawal period. 8) No drug-induced changes in kidney function were detected by PSP (Phenolsulfonphthalein) test. 9) Hematological examinations revealed significant decrease in erythrocytes counts and packed cell volume with dose dependency in male animals of the dosage groups of 2.50 m

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A teratogenecity study was performed in Sprague-Dawley rats treated orally with trandolapril (RU44570) at the dosage levels of 3, 30 and 300 mg/kg/day from day 7 to day 17 of pregnancy. In each group, 24 or 25 female rats were sacrificed on day 20 of pregnancy for the examination of their fetuses, and 14 or 15 female rats were allowed to litter naturally for the postnatal examination of their offspring. Clinical symptoms and mortality attributable to administration of RU44570 were not observed in the dams (P). Body weight gain and food consumption were slightly depressed in the 300 mg/kg dosage group comparing with those of control group. However, RU44570 showed no adverse effect on the fetal mortality, prenatal development or teratogenecity of the fetuses. Incidence of dilatation of renal pelvis was slightly increased in fetuses in the 300 mg/kg dosage group comparing with that of the control group. However, the offspring in each treated group showed similar incidence of this abnormality to that of the control group in more advanced age. Therefore, these changes were considered to be reversible. No adverse effects on the postnatal development of the offspring containing reproductive ability were detected. The results suggest that non-effective dose level of RU44570 is 30 mg/kg for dams, 30 mg/kg for fetuses and 300 mg/kg for development in offspring, respectively.

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A perinatal and postnatal study was performed in female Sprague-Dawley rats treated orally with trandolapril (RU44570) at dosage levels of 3, 30 and 300 mg/kg/day from day 17 of pregnancy to postpartum day 21. In each group, 24 or 25 pregnant female rats were allowed to litter naturally for the postnatal examination of their offspring. Clinical symptoms and mortality attributable to the administration of RU44570 were not observed in the dams (P). In the 30 and 300 mg/kg group, food consumption was slightly lower than that of the control group during the lactation period, however RU44570 did not affect body weight gain. Incidence of dilatation of renal pelvis with higher value in kidney weight was increased in offspring (F1) in the 30 and 300 mg/kg dosage groups, and water consumption at the same dosage groups was higher than that of the control group. Body weight gain in offspring (F1) was depressed in each treated group and viability of offspring (F1) from postpartum day 0 to day 4 was slightly decreased in the 30 and 300 mg/kg dosage groups comparing with that of the control group. No adverse effects were observed on the other postnatal development of the offspring, such as differentiation, sexual maturation, reflex, motor activity, emotionality, learning ability and reproductive performance. No adverse effects were detected in the second generation offspring (F2). The results suggest that the non-effective dose of RU44570 is 3 mg/kg for dams (P), lower than 3 mg/kg for development in offspring and 300 mg for fetuses (F2), respectively.

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Antigenicity of trandolapril (RU44570) was evaluated using the following six standpoints: 1. active systemic anaphylaxis (ASA) in guinea pigs; 2. passive cutaneous anaphylaxis (PCA) in guinea pigs with serum of sensitized guinea pigs; 3. histamine release from lung tissue of sensitized guinea pigs; 4. Schultz-Dale reaction with isolated ileum of sensitized guinea pigs; 5. passive cutaneous anaphylaxis (PCA) in rats with serum of sensitized mice; and 6. delayed type skin reaction by Maximization test in guinea pigs. In the test of immediate type reactions, guinea pigs were sensitized by RU44570 (p.o.), an FCA emulsion of RU44570 (s.c.) or an FCA emulsion of incubate solution of RU44570 and normal guinea pig's serum, and mice were sensitized by a mixture of RU44570 and alum (i.p.). In the test of delayed type reaction, guinea pigs were sensitized by intradermal injection and patch application. 1. ASA in guinea pigs: No anaphylaxis symptoms were observed in any of the sensitized guinea pigs. 2. PCA in guinea pigs: PCA titer of sera from all the sensitized animals was less than l. 3. Histamine release from lung tissue: No histamine release was observed in any of the isolated lung tissue. 4. Schultz-Dale reaction: No contraction was observed in any of the isolated ileums. 5. PCA in rats: PCA titer of sera from sensitized BALB/c and C3H/He mice was less than 5. 6. Delayed type skin reaction test: No skin reactions were observed in any of the sensitized guinea pigs. From these results, it is concluded that RU44570 has no antigenicity under the conditions of the present study.

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Mutagenicity of trandolapril (RU44570) was evaluated by the reverse mutation test with bacteria (test strains used: Salmonella typhimurium TA100, TA98, TA1535, TA1537 and Escherichia coli WP2uvrA). The test was conducted by the preincubation method without metaboric activation (in the absence of S9 mix) and with metaboric activation (in the presence of S9 mix). The number of revertant colonies in the bacterial strains did not exceed twice that obtained in the solvent control either in the presence or absence of S9 mix. There was no dose-dependent increase in the number of revertant colonies observed. Based on the above results, it is concluded that RU44570 has no mutagenicity (gene mutation) under the conditions of the present study.

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