Lidocaine tripotassium phosphate complex laden microemulsion for prolonged local anaesthesia: In vitro and in vivo studies.

Lidocaine is widely used as a local anaesthetic in the clinical practice to manage pre- and post-operative pain, skin burns, etc. However, the short duration of action (< 2 h) of marketed dosage forms limit their ability to meet clinical needs. Herein, we prepared a lidocaine-tPP(tri potassium phosphate)-complex loaded microemulsion to achieve greater penetration, followed by destabilization of microemulsion in the skin layer to precipitate oil-complex to produce a depot effect in the skin for prolonging the effects of anaesthesia.