A human oral-throat cast integrated with a twin-stage impinger for evaluation of dry powder inhalers.
The aim of this study was to investigate the applicability of replacing the glass throat from a twin-stage impinger (TSI) with a human oral-throat cast. Monodisperse aerosols were used to calibrate the human oral cast-TSI at 60 L min(-1) and cut-off in particle size was compared with that of the TSI described in the British Pharmacopoeia which employs a glass throat. The amount of salbutamol sulphate (and lactose) delivered by the Cyclohaler depositing on various elements of the in-vitro model were determined. The calibration of the model containing a human oral-throat cast at 60 L min(-1) gave a particle size cut-off of 5.2 microm which was less than that of the TSI (6.3 microm). The oral-throat cast trapped more drug than the glass throat model with a formulation that employed the larger carrier (63-90 microm; P<0.05) while it trapped a lesser amount of drug with those filled with the lower size carrier (Lactochem, micronised lactose). The greater amount of lactose in the formulation that employed the larger-sized carrier (63-90 microm) was deposited closer to the inlet of the oral-throat cast than to the inlet of the glass throat model. Replacement of the glass throat in the TSI by the human oral-throat cast, leads to a change in deposition efficiency, with the cast having a higher filter efficiency and hence more aerosol particles being captured before their entry into the TSI. This should be investigated further to determine whether such a model might provide a more realistic assessment of the in-vivo characteristics of an aerosol in comparison with the TSI currently being employed, which utilises the glass throat as the portal of entry.
Faculty of Pharmaceutical Sciences, Prince of Songkla University, Hat-Yai, Thailand. srteerap@ratree.psu.ac.th
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Srichana
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Martin
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Marriott
D000280:Administration, Inhalation; D000420:Albuterol / Q000008:administration & dosage; D001993:Bronchodilator Agents / Q000008:administration & dosage; D002138:Calibration; D006801:Humans; D007785:Lactose / Q000008:administration & dosage; D008153:Lubrication; D008954:Models, Biological; D009330:Nebulizers and Vaporizers; D011208:Powders / Q000008:administration & dosage
D001993:Bronchodilator Agents; D011208:Powders; D007785:Lactose; D000420:Albuterol