Promising non-narcotic analgesic techniques for labour.

Epidural analgesia and spinal analgesia are the most effective techniques for relieving labour pain. Basically, local anaesthetics (i.e. bupivacaine) and opioids (i.e. fentanyl or sufentanil), especially when combined, produce excellent analgesia with minimal motor blockade. However, none of these agents is devoid of side-effects and analgesia remains sometimes imperfect, suggesting that new drugs would be welcome. Adrenalin and clonidine act on a2-adrenoceptors in the spinal cord and both have been found to improve analgesia. These two drugs have already been used in many patients and studies because the absence of neurotoxicity has been well documented. Clonidine looks more attractive, although sedation and hypotension limit its use. Other analgesic drugs are promising alternatives but are still at an experimental or very early clinical stage. Neostigmine and ketamine (without preservative) are not neurotoxic while midazolam neurotoxicity is still controversial. Intravenous remifentanil might prove useful when neuraxial analgesia is contraindicated.