RESUMO
OBJECTIVES: The pharmacokinetics of commercial and liposome-encapsulated mepivacaine (MVC) injected intra-orally in healthy volunteers was studied. METHODS: In this double blind, randomized cross-over study, 15 volunteers received, at four different sessions, 1.8 ml of the following formulations: 2% MVC with 1 : 100 000 epinephrine (MVC(2%EPI) ), 3% MVC (MVC(3%) ), 2% and 3% liposome-encapsulated MVC (MVC(2%LUV) and MVC(3%LUV) ). Blood samples were collected pre dose (0 min) and at 15, 30, 45, 60, 90, 120, 180, 240, 300, 360 min after injections. Liquid chromatography-tandem mass spectrometry was used to quantify plasma MVC concentrations. RESULTS: Pharmacokinetic analysis showed that the maximum plasma concentration (Cmax) and the areas under the curves (AUC(0-360) and AUC(0-∞)) after MVC(2%LUV) and MVC(2%EPI) injections were smaller (P < 0.05) than the equivalent figures for MVC(3%) and MVC(3%LUV). The time to maximum plasma concentration (Tmax) and the half-life of elimination (t½beta) obtained after the treatment with MVC(2%LUV), MVC(2%EPI), MVC(3%) and MVC(3%LUV) presented no statistically significant differences (P > 0.05). Cmax, AUC(0-360) and AUC(0-∞) after injection of the 2% formulations (MVC(2%LUV) and MVC(2%EPI) ) did not exhibit statistically significant differences (P > 0.05). The pharmacokinetics of MVC(2%LUV) were comparable to the pharmacokinetics of MVC(2%EPI). CONCLUSION: The liposomal formulation of 2% MVC exhibits similar systemic absorption to the local anesthetic with vasoconstrictor.
