Investigation and comparison of the performance of various throat spray devices using different types of nanoformulations with encapsulated lidocaine as a local anesthetic

Lidocaine is most often employed as a local anesthetic via the parenteral route, whereas advanced drug delivery systems are a key concept using needle-free formulations for improved drug stability, deposition, and sustained release. Three delivery systems (liposomes, ethanol-based proliposomes, and proniosomes) were prepared with and without cholesterol and delivered via four commercially available throat spray devices (referred to as A, B, C, and D) for their performance and deposition. Formulations without cholesterol demonstrated higher drug entrapment and release. Upon analysis, spray device A demonstrated lower numbers of actuations for priming and tailing-off phases and higher numbers of full actuations; thus, it delivered a lower number of total actuations. Therefore, each shot weight delivered a larger amount of formulation (189 mg; an average of all formulations) using spray device A than counterpart devices. Spray device A showed significantly superior plume geometry (including plume angle (59°), plume width (14 cm), and total plume length (54 cm) (an average of all three formulations)). Furthermore, spray device A showed a round-shaped spray pattern with an ovality ratio of 1.05 when compared to the crescent, oval, and irregular/star-shaped patterns and ovality ratios of 1.19, 1.07, and 1.16 by devices B, C, and D, respectively. In addition, spray device A exhibited longer phases (i.e., formation, evolution, and dissipation) and higher mass output, drug output, drug deposition, and aerosol output rate. Thus, spray device A and formulations without cholesterol were identified as the best combination for their superior performance and targeted drug delivery.