Comparative study of particle size distribution analysis by laser diffraction between dry and liquid dispersion methods

Particle size is an important variable, especially in the pharmaceutical industry, since this is one of the parameters that can influence medicines performance. Drugs can be administered by different routes of administration and in different dosage forms. The active products analyzed in this study are characterized as inhalation products to be administered as dry powder inhalers. This type of active product is characterized by particles between 1 μm and 5 μm. Particles in this diameter range can travel through the lungs to the bronchi and alveoli area, where they settle by sedimentation. The performance of these dosage forms is compromised if the API does not meet the specifications regarding particle size. Two techniques based on laser diffraction were used to determine the particle size distribution of several active pharmaceutical ingredients. Both work under the same principles, however, over the last 20 - 30 years, they have evolved differently. They present two major differences: the mathematical algorithm and the means of dispersion of the particles. Two types of equipment were used for this type of analysis: Malvern Mastersizer Hydro 2000 S and Sympatec (consisting of Helos, Rodos / M and Aspiros units) for the liquid and dry dispersion, respectively. To verify the accuracy of the results an electronic microscope, the Phenom ProX Generation 5, was used. After all the analyses and the comparison of the results it was observed that it is possible to obtain similar results of particle size distribution with different techniques. However, this is only verified if the analysis method of both equipments allow a complete particle deagglomeration. In this study, due to the inherent characteristics of the products and the limits of the equipment, difficulties appeared and made the particle deagglomeration process difficult