Methimazole

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.

Methimazole is active pharmaceutical ingredient effectively utilized in hyperthyroidism. Methimazole inhibits peroxidase as well as iodine interactions with thyroglobulin to produce triiodothyronine with thyroxine. Methimazole shows very low protein binding (1-10%) bounds to plasma proteins and easily metabolized by liver. In this investigation, efforts given to develop a sustained release matrix tablet of Methimazole. Sustained release drug delivery systems are for a maximum of 24 hours clinical effectiveness. Such systems are primarily for the drugs of short elimination half-life. However, drugs with long half-life also qualify if a reduction in steady state fluctuation is desired. Matrix tablets of methimazole were prepared by utilizing direct compression method. HPMC along with Sodium carboxy methyl cellulose used to retard drug release from the dosage form. Matrix tablets of methimazole were evaluated for different quality control test to improve quality of the product. In vitro release study of methimazole matrix tablets shows that polymer percentage used in the formula is enough to extend the release of the drug for at least 12 hr. In dissolution study of matrix of methimazole formulation F2 shows maximum drug release 97.93 % at the end of 6 hours while F1 shows least 83.64 %.