Evaluation of Nasal Inlet Ports Having Simplified Geometry for the Pharmacopeial Assessment of Mass Fraction of Dose Likely to Penetrate Beyond the Nasopharynx: a Preliminary Investigation.

Nasal cavity breakthrough to the airways of the lungs is associated with nasally inhaled droplets whose size is smaller than ca. 10 μm aerodynamic diameter that behave as an aerosol rather than a spray in terms of their transport. The purpose of the present laboratory-based study was to evaluate a nasal product quality control procedure involving a new inlet for the quantification of mass of such droplets emitted by commercially available aqueous nasal spray pump products by cascade impactor. This inlet is more representative of the adult nasal vestibule in terms of entry angle for the spray as well as internal volume for plume expansion. Sampling was also undertaken via a spherical 1-L glass expansion vessel as inlet, previously established for quantification of these aerosol droplets. The selected solution- and suspension-formulated products containing azelastine and fluticasone propionate respectively were shown to contain < 1% of the total spray mass per actuation associated with droplets < 14.1 μm aerodynamic diameter. These measurements were consistent with laser diffraction-based measurements of the entire droplet size distribution. Comparable measures of aerosol droplet mass fraction were obtained when the spray was sampled by the cascade impactor method using either the 1-L glass expansion chamber or the new metal inlet as entry for the spray produced by either product evaluated. We conclude that the metal inlet has the potential to be adopted as a suitable induction port in the assessment of nasal product quality, where currently no standardized inlet exists.