Lidocaine loaded nanostructured lipid carriers for prolonged local anesthesia: in vitro and in vivo studies

Lidocaine is widely used to manage local pain. The marketed dosage forms including gels, injections and ointments showed short duration of action (< 2 h). In this paper, the efforts have being made to develop lidocaine loaded nanostructured lipid carrier (NLCs), which on penetration in the skin layer showed prolong local anesthesia. The NLCs was formulated using gelucire (solid-lipid), capryol (liquid-lipid) and Tween 80. The scanning electron microscopy showed smooth and spherical NLCs. The particle size data indicate the size in the range of 98-221 nm. The ex vivo permeation data of lidocaine from the NLCs showed sustain release up to 10 h in comparison to the marketed ointment (up to 4 h). The high lidocaine retention in the skin tissue was observed with NLCs batches. The NLCs was safe in the skin irritation study. The radiant heat tail flick and sciatic nerve block model showed prolong local anesthesia in comparison to the marketed ointment. The study demonstrate the potential of nanostructured lipid carriers for prolong the local anesthesia for the effective management of local pain.