Pharmacokinetics and efficacy of 40 ml ropivacaine 7.5 mg/ml (300 mg), for axillary brachial plexus block — an open pilot study

Summary

In this study, the pharmacokinetics, tolerability and efficacy of 40 ml of ropivacaine 7.5 mg/ml (300 mg) for axillary brachial plexus block were investigated. With institutional review board approval, 10 patients presenting for surgery of the upper limb were enrolled in this open study. The axillary plexus was identified with a nerve stimulator and the study drug was injected into the neurovascular sheath. Fifteen venous blood samples were obtained from each patient for pharmacokinetic measurements over a 24-h period. All blocks were sufficient for surgery after 45 min without any need for supplemental analgesia or general anesthesia. The mean (SD) peak plasma concentration was 2.3 (0.8) mg/l at median t_max 54 min (range 16–92 min). The mean (SD) maximum free plasma concentration was calculated to be 0.12 (0.06) mg/l (range 0.07–0.29 mg/l). The t_1/2 was about 6 h. There were no clinical signs or symptoms of central nervous system and/or cardiac toxicity in any patient. Ropivacaine 7.5 mg/ml, used in a dose of 300 mg, was effective and well tolerated for axillary brachial plexus block.