Toxicity of Local Anaesthetics in Obstetrics II: Chloroprocaine— Research and Clinical Aspects

SUMMARY

It is indicated that the local anaesthetic chloroprocaine is not toxic to neural tissue at the usual clinical concentration. The evident clinical toxicity of the commercial chloroprocaine solution (Nesacaine) is probably due to the drug medium. Three factors are identified and discussed: (a) the presence of the antioxidant sodium bisulphite in significant concentration (0.2%); (b) the profound acidity of the drug solution in the commercial preparation (pH 3.0); and (c) the use of large volumes of anaesthetic solution to increase potency and decrease latency. This overwhelms tissue buffering capacity and may, in addition, lead to vascular limitation to spinal neural tissues. Methods of prevention and treatment are presented.