Effect of antidysrhythmic and analgesic drugs on haemodynamics and fibrillatory threshold.

Ten drugs with antidysrhythmic and analgesic properties were evaluated for their ability to increase the ventricular fibrillating threshold (V.F.T.) in pentobar-bitone-anaesthetized cats by the electrically induced ventricular fibrillation method. The effects of this procedure on general haemo-dynamic parameters have already been published (Rashid, 1980). Quinidine, pentazocine, propranolol, procainamide, pethidine and indoramin raised V.F.T. by 100% or more. These drugs had a minimal effect on haemodynamics except for propranolol and indoramin which significantly depressed these parameters. Meptazinol, D.P.H. and lignocaine raised V.F.T. by 92%,78%, 64% and34%respectively. No significant side effects of these drugs were noticed. The data indicates that the analgesics pentzaocine, pethidine and meptazinol, unlike morphine, were effective in raising the V.F.T. at doses causing minimal disturbance of cardiovascular dynamics in this experimental model. Pentazocine was shown to possess the best antidysrhythmic profile against electrically-induced ventricular fibrillation. The mode of action of all the test drugs used in this method and the suitability of this procedure for primary screening of potential antidysrhythmic agents are discussed (JPMA.31:141, 1981).