In vivo comparison of three orally active inhibitors of angiotensin-converting enzyme.

This study was designed to compare the activity of three structurally different drugs (SQ 14225 [captopril], SA 446 and MK 421) as inhibitors of angiotensin I-converting enzyme in vivo and to compare their effects on blood pressure in spontaneously hypertensive rats and one clip, two kidney renal hypertensive rats. All the three drugs were potent, orally effective converting enzyme inhibitors. The relative durations of their actions as inhibitors of angiotensin-converting enzyme, from longest to shortest, were as follows: MK 421, SQ 14225 and SA 446. MK 421 appears the most potent on a molar basis. In renal hypertensive rats the drugs appeared equipotent, although the duration of action of MK 421 was prolonged and SA 446 shorter than that of SQ 14225. SA 446 was less effective than the other two compounds in spontaneously hypertensive rats.