In contemporary times, there has been a rise in the utilization of dry powder inhalers (DPIs) in the management of pulmonary and systemic diseases. These devices underwent a swift advancement in terms of both the equipment utilized and the formulation process. In this review, the carrier physicochemical characteristics that influence DPI performance are discussed, focusing its shape, morphology, size distribution, texture, aerodynamic diameter, density, moisture, adhesive and detachment forces between particles, fine carrier particles, and dry powder aerosolization. To promote the deposition of the active principal ingredient deep within the pulmonary system, advancements have been made in enhancing these factors and surface properties through the application of novel technologies that encompass particle engineering. So far, the most used carrier is lactose showing some advantages and disadvantages, but other substances and systems are being studied with the intention of replacing it. The final objective of this review is to analyze the physicochemical and mechanical characteristics of the different carriers or new delivery systems used in DPI formulations, whether already on the market or still under investigation.

The powders used in the production of solid dosage forms must have ability to flow that allows their industrial processing. Although this property has been studied for most of the powders, in this study non-expected flow behaviors were observed for the model excipient used Mycrocrystalline Celulose (MCC). Several fractions with different sizes were fractioned by sieving of the model excipient and its flow behaviors were analysed by different methods. The shear cell results showed an increase of the flowability index (ff_c) with the increase of the particle size and consolidation stress. Some related information has been referenced in the literature, however, in this work it was shown for different size fractions that the ff_c decreased above a certain consolidation stress value (2000 - 4000 N/m²). The explanation of this phenomenon is based on the increase of the cohesion. Furthermore, it was also observed that the fractions with sizes between 125-180 µm present a ff_c higher than bulk powder (F_Total) with similar percentile (D_V50) indicating that this index is dependent on the size of the particles and also on its size distribution range. Thus, it can be affirmed that more homogeneous samples in size and with a narrower distribution present a better ff_c.