A computer model originally developed by Persons et al was modified according to MMAD and GSD and used to calculate regional deposition of the 18 aerosols. The human lung model was based on the following parameters: mouth breathing, functional residual volume 3,300 ml, tidal volume 750 ml, inspiration 2 s, expiration 2 s, no pause. Regional deposition was calculated for mouth and pharynx, conducting airways (Weibel model generations 0 to 16), and alveolated airways (Weibel model generations 17 to 23). The aqueous suspension of Вес-DLPC liposomes approximated 0.5N (0.0045 g/ml) saline solution. Body weight was assumed to be 62.5 kg for calculation of dosage. The computer model results demonstrated good correlation with experimental regional deposition data from several investigators. buy asthma inhalers
The properties of the Вес-DLPC liposome aerosols produced by 18 nebulizers are shown in Tables 1 and 2. Nebulizers were ranked according to increasing MMAD of the particles, ranging from 0.9 to 7.2 [im. Table 2 also shows each corresponding GSD and the calculated regional deposition percentage of each aerosol predicted by the computer model for the mouth, generations 0 to 16 and 17 to 23 of human respiratory tract, as well as the total deposition. There is increased Bec-DP deposition in the mouth as the MMAD increases to 2.1 |im and higher. Increases in GSD also influence the predicted deposition patterns, particularly in the mouth and generations 0 to 16. Figure 1 is a graphic presentation from Table 2 to show the relative values of MMAD and corresponding GSD of the particles generated. The MMAD increases in fairly regular increments (from 0.9 to 7.2 |im) except for nebulizer No. 18 for which the MMAD was radically greater than the others. The GSD rises gradually from 1.8 to 2.8 with increasing MMAD.
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