PHARMACOKINETIC AND CLINICAL-STUDY OF ROPIVACAINE AND BUPIVACAINE IN WOMEN RECEIVING EXTRADURAL ANALGESIA IN LABOR

We have compared, in a randomized, double-blind study, the pharmacokin etics of ropivacaine and bupivacaine during labour. Total and free pla sma concentrations of ropivacaine and bupivacaine were measured after the first of two extradural doses. The main dose was 20 mg (test dose) and 30 mg, with a top-up dose of 25 mg when requested. After the main dose, C(P)max (total) of ropivacaine (0.50 mg litre(-1)) was similar to that of bupivacaine (0.48 mg litre(-1)). At 20 min, C(P)max (free) of ropivacaine (0.04 mg litre(-1)) was higher than that of bupivacaine (0.02 mg litre(-1)) (P=0.0025). The clinical effectiveness of the blo ck was similar in both groups.