In Vivo–In Vitro Comparison of Deposition in Three Mouth–Throat Models with Qvar ® and Turbuhaler ® Inhalers

In vitro polydisperse aerosol deposition in three mouth-throat models, namely, the USP (United States Pharmacopeia) mouth-throat (induction port), idealized mouth-throat, and highly idealized mouth-throat, was investigated experimentally. Aerosol particles emitted from two commercial inhalers, Qvar (pMDI) and Turbuhaler (DPI), were used. The in vitro deposition results in these three mouth-throat models were compared with in vivo data available from the literature. For the DPI, mouth-throat deposition was 57.3 +/- 4.5% for the USP mouth-throat, 67.8 +/- 2.2% for the idealized mouth-throat, and 69.3 +/- 1.1% for the highly idealized mouth-throat, which are all relatively close to the in vivo value of 65.8 +/- 10.1%. In contrast, for the pMDI, aerosol deposition in the idealized mouth-throat (25.8 +/- 4.2%) and the highly idealized mouth-throat (24.9 +/- 2.8%) agrees with the in vivo data (29.0 +/- 18.0%) reported in the literature better than that for the USP mouth-throat (12.2 +/- 2.7%). In both cases, the USP mouth-throat gives the lowest deposition among the three mouth-throat models studied. In summary, both the idealized mouth-throat and highly idealized mouth-throat improve the accuracy of predicted mean in vivo deposition in the mouth-throat region. This result hints at the potential applicability of either the idealized mouth-throat or highly idealized mouth-throat as a future USP mouth-throat standard to provide mean value prediction of in vivo mouth-throat deposition.