Comparative haemodynamic alterations induced by pipecuronium and pancuronium

Haemodynamic effects of pipecuronium bromide (Pi.) and pancuronium bromide (Pa.) were studied on isolated rabbit's heart, guinea pig's tracheal chain as well as the blood pressure in pentobarbital anaesthetized dogs. Pi. induced negative inotropic and chronotropic effects on the isolated rabbit's heart especially in lower concentrations. However, higher concentrations provoked two opposite effects, negative chronotropic and positive inotropic activity. In addition, Pa. in lower concentrations caused positive inotropic and negative chronotropic activity, while higher concentrations induced negative inotropic and chronotropic activity. Cardioinhibitory actions of both tested drugs are not due to either cholinergic or beta 1-adrenergic blocking effect but it may be due to nicotine-like activity. In anaesthetized dogs, i.v. injections of both tested drugs produced a transient decrease in systolic and diastolic pressure in doses above the therapeutic level. This effect may be referred to the partial ganglion blocking effect of both tested drugs.