Ropivacaine pharmacokinetics after caudal block in 1-8 year old children

We studied the pharmacokinetics after caudal block of ropivacaine (2 mg ml( -1), 1 ml kg(-1)) performed in 20 children aged 1-8 yr undergoing subumbili cal surgery, in this open, noncomparative, multicentre study. Venous blood samples were collected up to 12-36 h. The mean (SD) peak plasma concentrati on, 0.47 (0.16) mg litre(-1), was achieved after 12-249 min. The free fract ion was 5% and the highest individual peak plasma concentration of free rop ivacaine was 0.04 mg litre(-1). Clearance was 7.4 (1.9) ml min(-1) kg(-1) a nd the terminal half-life 3.2 (0.8) h. Thus, the free plasma concentrations of ropivacaine were well below those associated with toxic symptoms in adu lts and the capacity to eliminate ropivacaine seems to be well developed in this age group. In this open study of 20 patients, ropivacaine was well to lerated and provided satisfactory postoperative pain relief without observa ble motor block.