TABLE 1

Emitted dose, purity, and particle size distribution of thermally generated aerosols

Each drug was dip-coated onto multiple stainless steel foil heating substrates. Selected substrates were extracted to allow HPLC determination of the amount of coated drug, and thus the average coating thickness. The other coated substrates were vaporized by heating the foil to ~350°C, and the resulting aerosol was either collected in a filter and analyzed for quantity and purity by HPLC or collected in a cascade impactor for analysis of aerosol particle size. Values in the table reflect the mean ± standard deviation from N = 3 experiments.

Drug
Molecular Weight
Melting Point
Coating Thickness
Emitted Dosea
Total Drug Recoveryb
Aerosol Purity
MMADc
GSDd
°C μm % % % μm
Midazolam 326 160 2.2 99.6 ± 0.7 99.6 ± 0.7 99.9 ± 0.1 2.5 ± 0.1 1.8 ± 0.03
Zolpidem 307 196 2.4 92 ± 5 94 ± 5 99.4 ± 0.1 1.9 ± 0.1 2.0 ± 0.2
Rizatriptan 269 121 2.1 98 ± 2 99 ± 2 98 ± 0.1 1.8 ± 0.1 2.7 ± 0.1
Atropine 289 116 2.9 98 ± 4 98 ± 4 97 ± 0.2 2.6 ± 0.1 1.7 ± 0.03
Sildenafil
475
189
0.53
84 ± 3
96 ± 4
97 ± 0.3
1.1 ± 0.1
1.9 ± 0.2

  • ↵ a Emitted dose is the percentage of coated drug that is released from the heating apparatus as aerosol.

  • ↵ b Total drug recovery is the sum of the percentage of coated drug emitted and the percentage found unmodified in the heating apparatus.

  • ↵ c MMAD is the aerosol mass median aerodynamic diameter.

  • ↵ d GSD is the geometric standard deviation (measure of breadth) of the aerosol particle size distribution; GSD is a unitless parameter ≥1.