Comparison of 0.5% levobupivacaine alone and 0.5% levobupivacaine with butorphanol given intrathecally in infraumbilical surgeries; a randomised control trial

Spinal anaesthesia was the first major regional technique introduced into the clinical practice.  Spinal anaesthesia is a safe, reliable and also inexpensive technique.  It has the advantage of providing surgical anaesthesia with prolonged post operative pain relief with use of various local anaestheticagents. It also blunts the intra-operative, autonomic, somatic and endocrine responses. Spinal anaesthesia has a faster onset and effective sensory and motor blockade. Spinal anaesthesiawas first performed in 1898 by August Bier. From then on it has been practiced extensively.1

Local anaesthetics interrupt neural conduction by inhibiting the influx of sodium ions through channels or ionophores within neuronal membranes. The molecular structure of all local anaesthetics consists of 3 components, a lipophilic aromatic ring, an ester or amide linkage and tertiary amine. Local anaesthetics are classified as short acting, intermediate and long acting. This is primarily due to differences in their affinity for protein. Bupivacaine most common LA used for regional anaesthesia but it has serious side effects like cardiac and neurotoxic.

Levobupivacaine, the pure S (-) enantiomer of the racemic Bupivacaine is a long acting amide local anaestheticwhich produces differential neuraxial block. It was synthesized aiming at finding local   bupivacaine but without its hazards as cardiac and central nervous system toxicity.  Levobupivacaine exerts its pharmacological action through reversible blockade of neuronal sodium channels.  It binds to the intracellular portion of sodium channels and blocks sodium influx into nerve cells, which prevents depolarization. The pka of levobupivacaine is 8.1, similar to the pka of the racemic bupivacaine.2