ROPIVACAINE 7.5 MG ML FOR ELECTIVE CESAREAN-SECTION - A CLINICAL AND PHARMACOKINETIC COMPARISON OF 150 MG AND 187.5 MG/

Background: The new, long-acting local anaesthetic ropivacaine has sho wn less systemic toxicity than bupivacaine and a concentration of 7.5 mg/ml can therefore be used for epidural anaesthesia in Caesarean sect ion. The present pilot study was undertaken to find indications for an optimal dosage by comparing the clinical effects, quality of anaesthe sia and pharmacokinetics of ropivacaine 150 mg (lower dose=LD) vs 187. 5 mg (higher dose=HD) for women undergoing elective Caesarean section under epidural anaesthesia. Methods: Sixteen full-term women scheduled for elective Caesarean section in two equal-sized consecutive groups received 20 or 25 ml ropivacaine epidurally in this non-randomised, op en study. Study parameters included sensory and motor blockade, circul atory response, intraoperative pain and discomfort, neonatal evaluatio n and pharmacokinetic determinations. Results: Block height varied bet ween T5 and T2 in the LD group, whereas the HD group produced 4 unnece ssarily high blocks (C8 in 3 women and C7 in 1 woman). Surgical anaest hesia was excellent in both groups. Circulatory stability was pronounc ed in the LD group (no ephedrine given), while 4 women required ephedr ine in the HD group. Neonatal outcome as judged by Apgar scores, umbil ical blood gas determinations and NACS scores were excellent in both g roups. The plasma concentration-time profiles indicated linearity in t he concentration range studied, with similar clearance values to those reported previously. Placental drug equilibrium was rapid; however, t he foetal drug exposure depended on intrauterine exposure time. Conclu sions: 20-25 ml ropivacaine 7.5 mg/ml produced very satisfactory condi tions for elective Caesarean section under epidural anaesthesia. In th is small population, 150 mg ropivacaine seemed optimal, while 187.5 mg produced unnecessarily extended block height in 50% of the women. (C) Acta Anaesthesiologica Scandinavica 41 (1997).