Abstract:

Objective To compare the pharmacokinetics between 0.894% ropivacaine methanesulfonate and 0.75% ropivacaine hydrochloride. Methods Forty patients undergoing lower abdominal or lower limb surgery were randomly divided into ropivacaine methanesulfonate group (n=20) and  ropivacaine hydrochloride group (n=20). Blood samples were collected from an antecubital vein before administration and 2, 5, 10, 20, 30, 45, 60, 90, 120, 180, 240, 300, 360, 720 and 1 440 min after administration, and the concentrations of ropivacaine methanesulfonate or ropivacaine hydrochloride were determined by reversed phase high performance liquid chromatography-ultraviolet method. The pharmacokinetic parameters were calculated by DAS 2.0 software and were compared between groups. Results The apparent volumes of distribution (Vd/F) of ropivacaine methanesulfonate and ropivacaine hydrochloride were (2.1±0.7) L/kg and (2.7±1.1) L/kg, respectively; the elimination half life time (T1/2β) were (333±89) min and (378±112) min, respectively; the total areas under the concentration-time curve (AUC0-∞) were (480±168) mg·min/L and (425±126) mg·min/L, respectively; the clearance rates (CL/F) were (4.6±1.3) mL/(min kg) and (5.1±1.3) mL/(min kg), respectively; the peak time (Tpeak) were (26±13) min and (29±20) min, respectively; and the maximum concentrations (Cmax) were (1 732±833) ng/mL and (1 345±341) ng/mL, respectively. There was no significant difference in pharmacokinetic parameters between groups (P>0.05). Conclusion The pharmacokinetics of 0.894% ropivacaine methanesulfonate are similar to those of 0.75% ropivacaine hydrochloride, and the pharmacokinetic data are consistent with two-compartment model. In addition, the metabolism of ropivacaine is not influenced by the change of base.

Key words: ropivacaine methanesulfonate, ropivacaine hydrochloride, ultraviolet, reversed phase high performance liquid chromatography, pharmacokinetics