Blood concentration of prilocaine and lidocaine after the use of topical anesthesia (Oraqix ) in lacerated wounds.

Background/aim: Soft tissue injuries have been reported as being sutured using only topical anesthesia applied in the laceration wound. The objective of this study was to assess the pharmacokinetic profile of components of Oraqix (2.5% prilocaine and 2.5% lidocaine) when applied in a laceration as compared to intact skin application in the mouse.

Materials And Methods: A total of 200 BALB/c male mice were used in this study. The mice were divided into three groups: group A: shaved and laceration group (80 mice); B: shaved and intact skin group (80 mice); and C: control group (shaved, no treatment; 40 mice) which underwent the same procedures but without application of Oraqix . Blood samples were collected over 90 min. Plasma sample analysis employing liquid chromatography coupled with the tandem mass spectrometric (LC-MS/MS) method was used to determine plasma concentrations of lidocaine and prilocaine. Pharmacokinetic analysis of mouse plasma concentrations was carried out by standard non-compartmental methods.

Results: Absorption of both lidocaine and prilocaine was rapid. C and AUC values of lidocaine were significantly increased by fourfold and twofold, respectively, in lacerated mouse skin compared to intact skin. Similarly, prilocaine's C and AUC values were also increased by 2.5-fold and fourfold, respectively, in lacerated skin compared to intact skin.

Conclusion: When Oraqix was applied directly into the skin laceration, the plasma concentration of lidocaine and prilocaine was significantly increased as compared to when applied on intact skin. The present study, albeit in mice, indicates that the plasma levels of lidocaine and prilocaine can reach very high levels when the thermosetting gel Oraqix is placed directly in wounds.