NEW AMIDE LOCAL-ANESTHETICS FOR OBSTETRIC USE

For a number of reasons, bupivacaine has become the most frequently us ed local anaesthetic in obstetric anaesthesia, despite the fact that i t has a narrower margin of safety than other local anaesthetics. In re cent years, advances in technology have made single-isomer formulation s of drugs available for clinical use. Generally speaking, the levo st ereoisomer of amide local anaesthetic has a lower potential for system ic toxicity than the dextro form of the drug while retaining anaesthet ic potency. Ropivacaine (Naropin(R), Astra Ltd), a homologue of mepiva caine and bupivacaine, has recently been released for use. Its clinica l efficacy appears to be quite similar to that of bupivacaine but it h as a greater margin of safety. The other drug currently being investig ated is levobupivacaine (Chirocaine(R), 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 analyse s are required to define more clearly their future role in obstetric a naesthesia.