Effects of epidural metoprolol and verapamil on the quality of blockade induced by lidocaine

Abstract

Inadequaecy of block quality in epidural anaesthesia is a challenging problem in clinical practice. It has been shown that intrathecal calcium channel blocker, verapamil, potentiates spinal anaesthesia with local anaesthetics. However, it has not been investigated the effects of epidural verapamil. It is also unknown whether epidural beta adrenergic receptor blockers which have local anaesthetic-like action, affect quality of block with local anaesthetics. In this study, we aimed to determine the effects of epidural verapamil or beta blocker, metoprolol, on the quality of block induced by lidocaine. Fourty male Wistar rats were chronically implanted with lomber epidural catheter. Tail flick (TF) and mechanical paw pressure (MPP) tests were used to assess thermal and mechanical antinociceptive thresholds, respectively. Motor function was assessed using a modified Langerman's scale. Although epidural verapamil (75 ?g) or metoprolol (30 ?g) alone showed neither sensory and motor block, the combination of lidocaine (100, 200, 400 ve 800 ?g) and verapamil or metoprolol produced more potent sensory and motor block when compared with lidocaine alone. We concluded that epidural metoprolol and verapamil increase quality of block induced by lidocaine, and further experimental studies are needed to be used in human.