Clonidine added to bupivacaine enhances and prolongs analgesia after brachial plexus block via a local mechanism in healthy volunteers

SummaryBackground and objective:The addition of clonidine to local anaesthetics enhances pain relief after peripheral nerve block, but the site of action is unproven.Methods:Seven healthy volunteers underwent three brachial block procedures using bupivacaine 0.25% 1 mg kg−1 + epinephrine 1 : 200 000