Characterization of Particles from Nonprescription Spray Drug Products

There is limited physical characterization in published literature for nonprescription spray drug products. This study examines the physical properties of nonprescription topical spray drug products, including the evolution of spray plumes and the potential for aerosol products to produce particles small enough to penetrate the unciliated airways. Laser diffraction was used to evaluate the particle size distribution (PSD) of particles released from commercial sunscreen sprays over horizontal distances of 10 to 60 cm. Early in the spray plume, PSD were found to trend toward larger particle sizes then shifted toward smaller sizes further from the spray cannister (≥ 25 cm). Common attributes (agglomeration, evaporation, settling) influenced spray properties such as plume length and particle size. The research effort in this study may inform future requirements aimed at limiting unintended inhalation exposure from spray drug products, reducing the need for certain animal studies.