Droplet size distribution, nasal product

Various studies (Bond et al. 1984 Newman et al. 1987a) have found droplet size distributions of aqueous nasal spray products to have mass mean (median) diameter values between 44 and 62 pun. These studies showed that the majority of the dose was deposited locally in the anterior one-third of the nose. The relationship between retention time and viscosity has shown that the addition of various concentrations of methylcellulose (MC) to a metered spray pump containing desmopressin resulted in a dose-related increase in mean particle size from 51 pan (0 percent MC) to 81 pan (0.25 percent MC) to 200 pirn (0.5 percent MC), without a change in mean spray weight. The longest retention time was observed for the 0.25 percent MC solution, which was attributed to its particle size (81 p,m) and not to an increase in viscosity, since a decrease in retention time was observed for the highest viscosity (0.5 percent MC) solution... 

Maintaining particle/droplet size distribution on stability is a key challenge in the development of nasal spray and orally inhaled products. Suspensions have the potential to agglomerate or to undergo particle size changes [28]. For solution products. 

The stability evaluation of nasal solutions and suspensions equipped with a metering pump should include appearance, color, clarity, assay, degradation products, preservative and antioxidant content, microbial limits, pH, particulate matter, unit spray medication content uniformity, number of actuations meeting unit spray content uniformity per container, droplet or particle size distribution, weight loss, pump delivery, microscopic evaluation (for suspensions), foreign particulate matter, and extractables and leachables from plastic and elastomeric components of the container, closure, and pump. 

---