Background: Nasal spray performance attributes are related to the formulation, device, and patient, with the delivery of precise doses with minimal waste being key goals during product development, especially for potent and high cost drugs.
Methods: We investigated the influence of replacing the traditional rigid dip tube with a weighted, flexible dip tube on spray weight and tail-off characteristics in five over-the-counter nasal sprays representing varying viscosities, metering chamber volumes, formulation volumes, and active ingredients. Nasal sprays were actuated in ways representative of patient use.
Results: Compared to inherently curved, rigid dip tubes that were actuated in their worst case orientation, we found that weighted, flexible dip tubes (that seek the lowest point in the bottle irrespective of orientation) significantly increase the number of full sprays (in four out of five products) and reduce the duration of the tail-off period (in three out of five products). Shaking significantly decreased the spray weight in Afrin, Rite Aid, and Zicam nasal sprays using the original rigid dip tubes, and Afrin, Nostrilla, and Rite Aid when flexible dip tubes were used.
Conclusions: This study demonstrated that flexible dip tubes can improve the performance of many nasal sprays, and that shaking may have negative effects on spray weight uniformity.