Lidocaine Microemulsion-Laden Organogels as Lipid-Based Systems for Topical Delivery

Abstract

Conventional organogel and microemulsion-laden organogels (microemulsion organogels) were developed to deliver the lipophilic drug, lidocaine, topically. Optimized formulations of lidocaine microemulsions of oil, water, and surfactant:cosurfactant (Tween® 20:ethanol), at ratios 4:1 and 2:1 v/v, were selected based on the droplet size and physical stability of microemulsions. Microemulsions were then loaded into organogels. Lidocaine conventional organogel was prepared without the addition of microemulsion and used as a reference. The rheological properties and release profiles of lidocaine organogels were investigated. Lidocaine conventional and microemulsion organogels displayed viscoelastic properties with more elastic behavior. Lidocaine conventional organogel exhibited the highest viscoelastic properties and lowest rate of release, whereas microemulsion organogel containing Tween® 20:ethanol (4:1 v/v) exhibited lower viscoelastic properties and higher rate of release compared to those of microemulsion organogel containing Tween® 20:ethanol (2:1 v/v). Type and composition of organogels dictated the viscoelastic properties and rate of release of lidocaine.