Flowability Evaluation of Dry Powder Inhalation formulations Intended for Nasal Delivery of Betahistine Dihydrochloride

For optimum deposition in the nasal cavity drug particles' size should be in the range 1-25 μm.However, such particles are not free flowing due to cohesion and static charge phenomena. Excipients can improve flowability and reduce particles aggregation. The aim of this study was to develop interactive mixtures of betahistine-loaded microspheres and different carriers for inhalation delivery with optimum flow properties.

Forty eight sample mixtures were prepared to study the influence of microspheres/carriers ratio on powder mixtures' flowability. All the mixtures were studied for angle of repose and Hausner ratio.

Blending the cohesive microspheres with the carriers resulted in lower angle of repose and HR which indicates improved flowability. With high microsphere/carrier ratio improved flow properties were observed.

The results show that good flowability depends on carrier properties and microspheres characteristics and confirm the thesis that choosing the proper carrier excipient is of great importance for effective nasal drug delivery.