8 New amide local anaesthetics for obstetric use

For a number of reasons, bupivacaine has become the most frequently used local anaesthetic in obstetric anaesthesia, despite the fact that it has a narrower margin of safety than other local anesthetics. In recent years, advances in technology have made singleisomer formulations of drugs available for clinical use. Generally speaking, the levo stereoisomer of amide local anaesthetic has a lowe rpotential for systemic toxicity than the dextro form of the drug while retaining anaesthetic potency. Ropivacaine (Naropin^®, Astra Ltd), a homologue of mepivacaine and bupivacaine, has recently been released for use. Its clinical efficacy appears to be quite similar to that of bupivacaine but it has a greater margin of safety. The other drug currently being investigated is levobupivacaine (Chirocaine^®, Chiroscience Ltd). Both drugs appear to be similar in efficacy to the currently used formulation of bupivacaine; however, they are more costly. Thus, cost-benefit analyses are required to define more clearly their future role in obstetric anaesthesia.