Pharmacokinetics and analgesic effect of ropivacaine following ilioinguinal/iliohypogastric nerve block in children.

Background: The aim was to investigate the efficacy, tolerance and pharmacokinetics of ropivavcaine when administered for ilioinguinal/iliohypogastric block in children. Methods: We examined the pharmacokinetics and analgesic efficacy after ilioinguinal/iliohypogastric nerve block with 3 mg.kg(-1) ropivacaine 5 mg.ml(-1) in 22 children, aged 1-12 years, who were scheduled for inguinal surgery. Sixteen of 22 patients had a postoperative pain score < 4 (Objective Pain Scale). Nine children were given supplementary analgesics during the first six postoperative hours. Results: The peak plasma concentration of total ropivacaine was 1.50 +/- 0.93 mg.l(-1) (mean +/- SD) (range 0.64-4.77 mg.l(-1)) 15-64 min after the injection. The peak plasma concentration of free ropivacaine was 0.05 +/- 0.03 mg.l(-1) (0.02-0.14 mg.l(-1)), which is well below the threshold for toxicity in adults. The terminal half-life was 2.0 +/- 0.7 h. No safety concerns or symptoms suggestive of systemic toxicity were observed. Conclusions: A dose of 3 mg.kg(-1) of ropivacaine given as a single ilioinguinal/iliohypogastric nerve block in 1-12-year-old children provides satisfactory postoperative pain relief, and is well tolerated.