Experimental Study of the Effects of Pipecuronium, Atracurium and Pancuronium on Cardiovascular System

The present work was undertaken to study the effects of pipecuronium, atracurium and pancuronium on isolated perfused rabbit heart, isolated rabbit atrium and on carotid arterial blood pressure as well as ECG changes with each drug administration. The results demonstrated that pipecuronium in a dose of 100 &kg B.W. had no significant effect on heart rate and carotid arterial blood pressure of anaesthetized cat. Atracurium (150 t@kg B.W.) produced 7.5% increase in basal heart rate and short lasting drop of arterial blood pressure lasting for approximately l- 1.5 min. followed by rapid recovery. Pancuronium (100 pg/kg B. W.) increased heart rate by about 15.5% @ < 0.05) and long lasting hypotension lasted for approximately 4-5 min. with gradual recovery to the pre-injection level. Pipecuronium and pancuronium produced no change in isometric contraction of rabbit atria in concentration range (5-20 pg/ml). However, atracurium in concentrations of 30, 60, 120 Pg/ml produced dose-dependent increase in contraction of rabbit atria without any effect on heart rate. When the chronotropic effects of three drugs were investigated using acetylcholine as an agonist on isolated perfused rabbit heart, it was found that pancuronium but not pipecuronium and atracurium, produced a significant degree of antagonism to the bradycardia produced by acetylcholine. We concluded that pipecuronium appears to be a suitable replacement for pancuronium for the production of muscular relaxation of relatively long duration in patients in whom elevation of heart rate has to be avoided. Also, the vagolytic effects of pancuronium is desirable, especially when counter acting the bradycardic tendency of ljlrge doses of fentanyl. And that the transient haemodynamic effect of atracurium is probably of little clinical significance in the healthy patient. The effect may be more important in the haemodynamically unstable patient who is hypovolaemic or has cardiovascular disease. 537