Percorrer por autor "Arantes, Luiza Gomes"
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- Solid-liquid equilibrium and polymorphic behaviour of metacetamol: an experimental investigationPublication . Arantes, Luiza Gomes; Martins, Mónia; Pinho, Simão; Okuma, Adriana AkemiThe study of solubility, thermal properties, and crystalline structure of drugs is of great importance in pharmaceutical applications, as these parameters are directly related to their stability, bioavailability, and therapeutic efficacy. Accordingly, the present work aims to analyse important pharmaceutical compounds, and to determine relations between their crystal structure and solubility behaviour. Three compounds of pharmaceutical relevance were initially selected, namely benzophenone, sulfamerazine, and metacetamol, and a database containing their physicochemical properties and solubilities in water and common organic solvents was compiled. The available solubility data for metacetamol were scarce and essentially limited to water and acetone, highlighting the need for additional experimental data in pharmaceutically relevant solvents and their mixtures. Based on this analysis, and considering the available information and pharmaceutical relevance, metacetamol was selected for further experimental study. The solubility of metacetamol was measured by the gravimetric shake-flask method in water, ethanol, acetone, and ethyl acetate over the temperature range from 298.15 to 323.15 K. In all pure solvents, solubility increased with temperature, confirming the positive temperature dependence of the dissolution process. The solubility followed the order water < ethyl acetate < acetone < ethanol. Metacetamol solubility was also determined in binary solvent mixtures at 313.15 K, namely water + ethanol, water + acetone, and ethanol+ acetone. A clear cosolvency effect was observed in all systems, indicating a non-ideal solvent behaviour and demonstrating that mixed solvents can provide a more favourable solvation environment than the corresponding pure solvents. Solid-phase characterization by X-ray diffraction showed that the recovered solids remained in the same crystalline phase after equilibration with the investigated pure solvents and binary mixtures. NMR analysis further confirmed the chemical integrity of metacetamol. The thermodynamic properties of solution were estimated from the temperature dependence of the mole fraction solubility. Positive enthalpy dissolution values were obtained for all solvents, confirming that metacetamol dissolution is endothermic. Overall, this work provides new experimental solubility and thermodynamic data for metacetamol, contributing to a better understanding of its solvent-dependent dissolution behaviour and supporting future studies related to crystallization, polymorphism, and pharmaceutical formulation.