Formulation and Evaluation of Methimazole-Loaded Emulgel for the Treatment of Melasma

Melasma is a common acquired hyperpigmentation disorder characterized by the development of irregular, symmetrical, and brownish facial patches, which can significantly affect the appearance and quality of life of affected individuals. Methimazole, an antithyroid drug, has been investigated for its potential topical depigmenting activity due to its ability to interfere with melanogenesis. The present study was undertaken to develop and evaluate a methimazole-loaded emulgel intended for topical application in the management of melasma. Pre-formulation studies were carried out to determine the solubility, melting point, ultraviolet absorption maximum, and drug–excipient compatibility. The prepared formulations were evaluated for their physical appearance, homogeneity, pH, viscosity, spreadability, drug content, and in-vitro drug release characteristics. Drug–excipient compatibility was assessed using Fourier-transform infrared spectroscopy, while differential scanning calorimetry was employed to investigate the thermal characteristics of the formulation. The developed emulgels exhibited satisfactory physical characteristics with acceptable pH, viscosity, spreadability, and drug content, indicating their suitability for topical administration. In-vitro drug release studies demonstrated sustained release of methimazole from the emulgel formulations over the studied period. The release data were further analysed to understand the mechanism of drug release. Short-term stability studies were also performed to assess the physical and chemical stability of the prepared formulations. Overall, the study demonstrated the successful development of a methimazole-loaded emulgel with desirable physicochemical properties and controlled drug-release characteristics, suggesting its potential as a topical formulation for further investigation in the management of melasma. Emulgel have several merits like greaseless, easily spreadable, easily removable, emollient and transparency.