A CLINICAL AND PHARMACOKINETIC COMPARISON OF ROPIVACAINE AND BUPIVACAINE IN AXILLARY PLEXUS BLOCK

The clinical and pharmacokinetic properties of ropivacaine and bupivac aine, both 5 mg/mL, used in axillary plexus block were compared in 60 patients in this randomized, double-blind, parallel-group study. The a xillary plexus was identified with a nerve stimulator and 30, 35, or 4 0 mL of drug, depending on body weight, was injected into the perivasc ular sheath. In 20 patients, venous blood samples for the pharmacokine tic measurement were obtained over 24 h. The median onset times for an esthesia and complete motor block were in the range of 12-48 min and 5 -20 min, respectively. Thirty-eight percent of patients in the ropivac aine group and 29% in the bupivacaine group needed additional nerve bl ock(s) or supplementary analgesia and 7% in the bupivacaine group need ed general anesthesia for surgery. Anesthesia was achieved in 52%-86% of the evaluated six nerves in the ropivacaine group and in 36%-87% in the bupivacaine group; the lowest figures were seen in the musculocut aneous nerve. In the pharmacokinetic study the mean peak plasma concen trations (C-max) were 1.28 +/- 0.21 mg/L in the ropivacaine group and 1.28 +/- 0.47 mg/L in the bupivacaine group and the median times to pe ak plasma concentration (t(max)) were 0.86 h and 0.96 h,respectively. The median terminal half-lives (tw) were 7.1 hand 11.5 hin the ropivac aine group and the bupivacaine group, respectively (P = 0.07). No stat istically significant differences were found between ropivacaine and b upivacaine in either the clinical or the pharmacokinetic comparisons.