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Poorly water soluble drugs tend to have low bioavailability, however, this can be improved by several methods. One of the most promising strategies is the employment of solid dispersions to increase water solubility and enhance oral bioavailability of these drugs. Nonetheless, the mechanisms of solid dispersion formation may influence the solid-state characteristics and thus the dissolution profile. In this study, rotary evaporation and spray-drying solvent evaporation techniques were used to produce solid dispersions of the anti-allergenic loratadine, a class II drug in the Biopharmaceutical Classification System, with the hydrophilic carrier polyvinylpyrrolidone K-30. Thermogravimetry, differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, particle size distribution by light scattering, solubility at different pHs, and dissolution profile experiments were carried out to evaluate the solid dispersions and physical mixtures. Results showed an increase in solubility, especially in acid medium, where the drug is protonated, and an enhancement in dissolution profiles, following first order kinetic, of solid dispersions manufactured by both the rotary evaporation and the spray-drying methods. Both methods proved to be equally adequate, when compared to physical mixtures. This is a consequence of particle size reduction, increased wettability due to intimate contact of the drug with the hydrophilic matrix, increased surface area, and the conversion of the crystalline to the amorphous state, which proved to be stable after 6 months at room temperature.

Fármacos pouco solúveis em água tendem a possuir baixa biodisponibilidade. Diversos métodos têm sido estudados para promover o aumento da solubilidade em água de fármacos pouco solúveis. As dispersões sólidas têm sido pesquisadas como uma estratégia de aumentar a solubilidade em água e melhorar o desempenho destes fármacos na biodisponibilidade, entretanto os mecanismos completamente elucidados parecem variar da combinação do fármaco e do polímero, bem como do método de obtenção empregado. No presente estudo, através da técnica de evaporação do solvente desenvolveu-se dispersões sólidas de loratadina em polivinilpirrolidona a fim de melhorar a solubilidade do fármaco. Poorly water soluble drugs tend to have low bioavailability. Several methods have been studied to promote increased water solubility of poorly soluble drugs. Solid dispersions have been investigated as a strategy to increase the water solubility and improve performance on the bioavailability of these drugs, however elucidated the mechanisms seem to vary the combination of drug and polymer and production method employed. In this study, using the technique of solvent evaporation was developed from solid dispersions in polyvinylpyrrolidone loratadine to improve the solubility of the drug.