Microemulsions: Unique Properties, Pharmacological Applications, and Targeted Drug Delivery

Abstract

Microemulsions, comprising oil, water and a surfactant, in association with some co-surfactant, are thermodynamically stable systems. They have found applications in a large number of chemical and pharmacological processes due to their unique properties such as large interfacial area, low interfacial tension, and most importantly, the ability to solubilize and deliver hydrophobic drugs. In addition to the oral and intravenous route, they are suitable for drug delivery through the ophthalmic, vaginal, pulmonary, dental, and topical routes. This review highlights the properties and several recent developments in the use of microemulsions for medical treatment purposes including targeted drug delivery.

Exploring the Versatility of Microemulsions in Cutaneous Drug Delivery: Opportunities and Challenges

“…Microemulsions are a type of nanocarrier that consist of an oil phase, a surfactant, a co-surfactant, and an aqueous phase [ 26 ]. These components are carefully selected and mixed to form a thermodynamically stable system that is optically transparent and has a low interfacial tension [ 17 , 19 , 27 ]. In addition, microemulsions have several advantages over conventional drug delivery systems [ 28 ].…”

“…Microemulsions are optically transparent [ 17 ], thermodynamically stable [ 10 , 18 ], and possess a low interfacial tension, making them an attractive option for drug delivery [ 19 ]. They are typically composed of an oil phase, a surfactant, a co-surfactant, and an aqueous phase [ 17 , 20 ].…”

Lipid-Based Drug Delivery System (LBDDS): An Emerging Paradigm to Enhance Oral Bioavailability of Poorly Soluble Drugs

“…By reducing the oil-water interfacial tension through interfacial adsorption, the amphiphiles (surfactant/co-surfactant combination) reduce the positive free energy change of dispersion associated with the creation of a surface. The following categories of microemulsions exist depending on the type of dispersed particles: [40].…”

“…In this instance, the aqueous phase is the "continuous" (outer) phase and the oil is the "discontinuous" (inner) phase. [40].…”

“…There exist bicontinuous structures in systems when the amounts of water and oil are comparable. In the presence of a continually fluctuating, surfactant-stabilized interface with a net curvature of zero, both the oil and the water exist as a continuous phase [40]. Advantage…”