Thermal Properties and Rheological Behaviors of the Anesthetic Gel Containing Lidocaine and Prilocaine

Abstract

Objectives: To develop a gel containing lidocaine and prilocaine and to characterize its thermal and rheological properties. Methods: The thermal property by differential scanning calorimeter (DSC), solubility of the drugs in co-solvent system, suitable gelling agent and rheological behavior were evaluated. Results: DSC study revealed that lidocaine:prilocaine at the ratio of 1:1 could form a eutectic mixture. The co-solvent system, 35% w/w ethanol was used to dissolve these drugs. The 1% w/w carbopol 940 was an appropriate gelling agent. The developed gel and EMLA® cream showed a comparable pseudoplastic flow (shear thinning system). In addition, the changing of temperature did not affect the gels’ rheological behavior. Conclusion: This study of the lidocaine-prilocaine gel formulation can be useful for the further development. Keyword: lidocaine, prilocaine, gel, eutectic mixture, thermal properties, rheological behaviors