Validação do método de análise de tamanho de sólidos particulados da matéria-prima cloridrato de venlafaxina por difração a laser

Abstract

The particle size is a physical property of the drugs that exerts great influence in several stages of the of new medicines, and it can affect the bioavailability of drugs and the productive processes. In this work, the method’s size of the solid particles of the rawmaterial Venlafaxine hydrochloride was validated by laser diffraction using two different optical models, according to the Mie Theory and Fraunhofer Approximation. The refractive index of the active Venlafaxine hydrochloride was determined by the Savevy’s method through the concentration variation of active solutions in water (0.1% up to 1.0%), with an average value found around to 1,550. The validation of the method was performed by proving the repeatability and intermediate precision in addition to the accuracy, according to the acceptance criteria of the American Pharmacopoeia. The size distribution for the pharmaceutical input for six samples presented precision results with relative standard deviation below 5.5% for the means of D10, D50 and D90 on two different days of analysis, ensuring the intra- and inter-method precision of the method. The accuracy of the method was demonstrated by comparing the results with the optical microscopy of the material, which is among the range quantified by the laser diffraction technique. Therefore, it was possible to conclude that the choice of the optical model to determine the particle size distribution influences the results, since the Fraunhofer Approximation results in deviations in the results of the particle sizes of less than 10 μm.