General pharmacology of CK‐2130: A new selective positive inotrope

Abstract

CK-2130 is a new imidazolone developed to treat congestive heart failure. We compared CK-2130 to four inodilators and ouabain in several pharmacologic models. Intravenous (i.v.) administration of CK-2130 to pentobarbital-anesthetized dogs (0.03 to 1 mg/kg) relatively selectively increased myocardial dP/dT when compared to the dual positive inotropic and vasodilator activity of milrinone, enoximone, imazodan, and piroximone. Milrinone and piroximone (600 mg/kg, P.o., and 30-300 mg/kg, i.p.) were central nervous system depressants in mice. CK-2130 (100 mg/kg, i.v. and 600 mg/kg, i.p. and p.0.) was not depressant. Gastric acid secretion in the guinea pig was not affected by CK-2130 (1 mg/kg, i.v.) and was inhibited by milrinone (1 mg/kg, i.v.) and enhanced by enoximone (1 mg/kg, i.v.). CK-2130 and milrinone (0.03-1 mg/kg, i.v.) did not affect rabbit sciatic nerve-gastrocnemius muscle function. CK-2130, piroximone, imazodan, and milrinone (100 pM) did not affect sympathetic neurotransmission, postsynaptic receptors, or guinea-pig nonvascular smooth muscles but relaxed canine arteries and veins. Ouabain (1-100 KM) initially facilitated, then inhibited, sympathetic neurotransmission, contracted vascular and non-vascular smooth muscles, enhanced the vas deferens contraction to norepinephrine, and inhibited uterine contractions to bradykinin (10 ELM). CK-2130, milrinone, piroximone, and imazodan (0.1 to 100 p,M) inhibited human platelet aggregation produced by adenosine diphosphate and sodium arachidonate. Thus, CK-2130, a relatively selective positive inotrope, should be devoid of adverse central nervous system; neural, smooth, and skeletal muscle; and gastrointestinal side effects associated with digitalis and enoximone therapy.