Free versus liposome-encapsulated lignocaine hydrochloride topical applications

The influence of encapsulating lignocaine hydrochloride, in a liposomal delivery system on its release from a topical formulation was studied. Liposomes were prepared from a mixture of L-alpha-dipalmitoylphosphatidyl choline (DPPC) and cholesterol in different molar ratios with or without charge inducing agents. The swelling time affording maximum entrapment was tested from 0-48 h at 53 degrees C. The percentage of drug entrapped in liposomes was found to be charge dependent and more pronounced for negatively charged liposomes. The amount of drug entrapped increased by increasing the ratio of cholesterol. The selected formulations were evaluated in vivo using the pin prick method. The results revealed localized and prolonged activity of lignocaine contained in liposomes when compared with an equivalent conventional topical application.