Delivery of nasal powders of beta-cyclodextrin by insufflation

PURPOSE: Delivery of nasal powders of granulated beta-cyclodextrin by insufflation was studied in order to find the relationship between powder properties and delivery behavior. METHODS: Three nasal powder formulations, prepared by granulating beta-cyclodextrin with different binders, were delivered from a powder insufflation device, in which the dose to be emitted was loaded in a gelatin capsule. The delivery sequence of powder was recorded and characterized using an image analysis program. RESULTS: Particle size was the main parameter affecting nasal powder delivery, both as to the amount of dose sprayed and the aspect of cloud produced. Between 50-150 mu m of particle size a substantial change in delivery behavior of powders was observed. Powder of around 100 mu m in size showed useful insufflation characteristics for nasal delivery. Bioavailability of nasal formulations of progesterone/beta-cyclodextrin powders was discussed in term of delivery behavior. CONCLUSIONS: The formulation approaches for improving nasal delivery of powders require the use of size optimized carriers. Insufflation of powders over 50 mu m can favour the particle deposition by impaction, whereas for powders below 50 mu m, deposition by sedimentation is moved. beta-cyclodextrin is a suitable carrier for achieving high systemic availability following nasal administration of powder formulations.