experimental study on the possible muscle relaxant action of verapamil and its interaction with other non-depolarizer muscle relaxants

ABSTRACT

In this work the neuromuscular blocking activity of verapamil was tested. In vivo studies done on gastrocnemius sciatic nerve preparation of chloralozed anesthetized cats showed dose-related muscle relaxant effect of verapamil which was reversed by neostigmine. It was found also to potentiate the effect of nondepolarizing muscle relaxant drugs [pancuronium and vecuronium] and this effect was not reversed by neostigmine or CaCl2. In vitro studies done on isolated frog's rectus abdominus supported the in vivo studies where verapamil showed a dose-dependent significant reduction of acetylcholine- potassium chloride and aminophylline-induced contraction. This relaxant effect of verapamil was antagonized by neostigmine. In addition, verapamil also potentiated the muscle relaxant effect of DTC on isolated frog's rectus abdominus. Therefore, this potentiating effect of verapamil on the non-depolarizing muscle relaxants which was not reversed by neostigmine or calcium chloride should be put into consideration during anesthetizing patients pretreated with verapamil. However, human studies are also needed