Safety and tolerance of single oral doses of trandolapril (RU 44.570), a new angiotensin converting enzyme inhibitor

Summary

The safety and tolerance of single oral doses of a new angiotensin converting enzyme (ACE) inhibitor, trandolapril have been examined in 90 healthy male volunteers, in a randomised, double blind, placebo-controlled study. The subjects were divided into 10 groups, each of 9 subjects and treatments (6 subjects on trandolapril and 3 on placebo per group) were allocated by unbalanced randomisation. Ten single, increasing oral doses were tested: 0.125, 0.25, 0.5, 1, 2, 4, 8, 16, 24 and 32 mg. The assessment criteria were clinical (monitoring of blood pressure, heart and respiratory rate, electrocardiogram, temperature and evaluation of behaviour and side effects) and routine laboratory tests.

Blood pressure did not fall except for a slight drop in diastolic pressure during the first 4 h following the 32-mg dose. However, although an effect of the compound cannot be excluded, the reduction in blood pressure may have reflected intersubject variability. No orthostatic hypotension was observed. There was no change in the other vital signs, and in particular no increase in heart rate was observed. No serious adverse effect was encountered.

The pharmacological activity of the compound was studied by assaying plasma ACE activity. Inhibition of ACE was linearly dose-dependant from 0 (placebo) to 2 mg, and above that dose, the inhibition was nearly total. ACE activity was markedly reduced within 30 min after administration of trandolapril, and maximal inhibition was observed from 2–4 h onwards, lasting for up to 24 h after dosing. For doses above 2 mg, inhibition was still 40% of the basal activity on Day 8 after dosing.