Effect of gender and device mouthpiece shape on bolus insulin aerosol delivery using the AERx pulmonary delivery system

Purpose. A study was designed to compare differences in insulin aerosol deposition profiles in healthy male and female subjects, as well as examine the effect of mouthpiece cross-sectional shape, volume, and taper on deposition profiles using a developmental AER(x) pulmonary delivery system. Methods. Six mouthpieces were screened in the laboratory, and three were selected for clinical investigation: a cylindrical mouthpiece with constant-cross-sectional area, an elliptical mouthpiece with constant-cross-sectional area, and a tapered elliptical mouthpiece with an exit cross-sectional area equal to one half the entrance cross-sectional area. Results. There was no significant difference in the lung dose or in the deposition pattern between males and females (p > 0.05, by ANOVA). The cross-sectional shape of the mouthpiece had no significant effect on the clinical lung dose or the deposition pattern ( p > 0.05, by ANOVA), although in vitro testing showed lower emitted dose values with the tapered elliptical mouthpiece (by ANOVA and Duncan's multiple range test, alpha = 0.05). Using the tapered mouthpiece in the clinic resulted in significantly more deposition on the mouthpiece itself when compared to the nontapered mouthpieces. Conclusion. Inhalation of insulin using the AER(x) system was insensitive to differences in male and female respiratory tract geometry across all mouthpiece designs examined.