Step-by-Step Industrial Development of Microemulsion for Topical Application

Abstract

Microemulsions are stable nanoscale drug delivery systems formed from oil, water, surfactants, and cosurfactants, with droplet sizes of 10-200 nm. They offer high solubility, easy preparation, stability, and the ability to incorporate both lipophilic and hydrophilic molecules. Their nanoscale droplets increase skin contact, while SFs temporarily disrupt the barrier to improve absorption. Higher stability of microemulsions can be achieved by using Pseudo-ternary phase diagrams. Non-ionic SFs like tween and span, along with short-chain alcohol CSFs, are common. The oil phase includes fatty acid esters and vegetable or natural oils with penetration-enhancing properties. A quality target product profile is quintessential to defining the desired microemulsion properties. Critical quality attributes define the physicochemical properties of microemulsions, their target values, and significance. Evaluation involves droplet size, pH, viscosity, zeta potential, conductivity, stability, and in vitro release. Studies show drugs like cyclosporine, methotrexate, and tacrolimus in microemulsions improve skin retention, reduce systemic absorption and toxicity, and produce positive histopathological effects. Microemulsions can be formulated as gels, offering high permeability, spreadability, and sustained release. The manuscript systematically presents a sequential, logical workflow that mirrors actual industrial development processes. It systematically reviews advances in research, preparation methods, and evaluation techniques for microemulsions used in transdermal drug delivery, especially for psoriasis treatment. The article lacks original experimental data; all information and conclusions are based on published literature to support formulation development and industrial application in this area.