Preparation, Characterization, and Evaluation of Liposomal Dispersions of Lidocaine

Abstract

Lidocaine, a local anesthetic agent, was encapsulated into liposomes employing the conventional lipid-film hydration technique. An attempt was made to freeze dry the aqueous liposomal dispersions. The prepared liposomal dispersions were investigated by differential scanning calorimetry (DSC), transmission electron microscopy (TEM), scanning electron microscopy (SEM), ³¹ P-nuclear magnetic resonance (NMR) spectroscopy, and laser counting studies for characterization. The skin partition coefficient for liposomal lidocaine was calculated. The results showed that lidocaine incorporated into the liposomes got selectively partitioned and localized in the skin to a great extent. A topical liposomal gel formulation containing 2% w/w lidocaine was prepared using Carbopol-934 as the gelling agent. The prepared formulation was tested for its local anesthetic efficacy employing the pinprick test. The liposomal preparation of lidocaine gave a much longer duration of action compared to the conventional topical formulation.