SQ 27,786 and SQ 28,853 were designed to possess both angiotensin converting enzyme (ACE) inhibitory and diuretic properties. Both compounds were given to conscious male Sprague-Dawley rats and mongrel female dogs to determine ACE inhibitory and diuretic activities. All animals had previously been equipped with indwelling arterial and venous catheters. Both compounds resulted in dose-related inhibition of an angiotensin I pressor response in rats after i.v. administration. The maximum response and duration of effect of both compounds were similar to that seen with equimolar doses of captopril. Oral doses of SQ 28,853 (50.0 mUmol/kg) and SQ 27,786 (15.0 mUmol/kg) resulted in 15 and 64% inhibition of ACE, respectively. In conscious normotensive dogs, both compounds (2.0 mg/kg, i.v.) resulted in complete inhibition of ACE. Urine volume was increased by 153 and 667% after SQ 27,786 and SQ 28,853, respectively. Similarly, sodium excretion was increased by 336% after SQ 27,786 and by 650% after SQ 28,853. SQ 27,786 and SQ 28,853 increased potassium excretion by 54 and 115%, respectively. No significant changes in blood pressure were observed with either compound in either species. These results demonstrate that both SQ 27,786 and SQ 28,853 are potent ACE inhibitors and diuretic agents in vivo.
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