Janssens Hettie M, De Jongste Johan C, Hop Wim C J, Tiddens Harm A W M
Department of Pediatrics, Division of Respiratory Medicine, Sophia Childrens Hospital/Erasmus Medical Center, Rotterdam, the Netherlands.
Chest. 2003 Jun;123(6):2083-8. doi: 10.1378/chest.123.6.2083.
The particles of a new hydrofluoroalkane-134a (HFA)-beclomethasone dipropionate (BDP) metered-dose inhaler (Qvar; 3M Pharmaceuticals; St. Paul, MN) are considerably smaller than those of chlorofluorocarbon (CFC)-BDP. This may improve lung deposition in infants who inhale nasally and have irregular breathing patterns and small airways.
To compare the dose delivered to the lungs of HFA-BDP and CFC-BDP at different breathing patterns using an upper airway model of an infant.
An anatomically correct upper airway model of a 9-month-old child with an open nasal airway was connected to an impactor and breathing simulator. HFA-BDP, 100 microg, and CFC-BDP, 100 micro g, were delivered to the model through a detergent-coated, small-volume spacer. The total dose leaving the model (lung dose), its particle size distribution, and median mass aerodynamic diameter (MMAD) were assessed during simulated tidal breathing with tidal volumes (VTs) of 50 mL, 100 mL, and 200 mL, and 30 breaths/min. Dose was expressed as percentage of nominal dose.
Lung doses for HFA-BDP were 25.4%, 26.5%, and 30.7% compared with 6.8%, 4.8%, and 2.1% for CFC-BDP at VTs of 50 mL, 100 mL, and 200 mL, respectively. The dose of particles < 2.1 microm to the lung for HFA-BDP was 23 to 28% compared with 0.6 to 0.8% for CFC-BDP. The lung dose of CFC-BDP mainly consisted of particles between 2.1 microm and 4.7 microm. MMAD for HFA-BDP was 1.2 microm, and 2.6 to 3.3 microm for CFC-BDP depending on VT. The lung dose for CFC-BDP decreased significantly with increasing VT. HFA-BDP lung dose did not alter significantly with VT.
In this infant model study, the use of HFA-BDP with a high dose of particles < 2.1 microm improves the dose delivered to the lungs substantially. Furthermore, the large proportion of extra-fine particles in HFA-BDP results in lung doses less dependent on breathing pattern compared with CFC-BDP.
新型氢氟烷烃-134a（HFA）-二丙酸倍氯米松（BDP）定量吸入器（Qvar；3M制药公司；明尼苏达州圣保罗）的颗粒比氯氟烃（CFC）-BDP的颗粒小得多。这可能会改善经鼻吸入且呼吸模式不规则和气道较小的婴儿的肺部沉积。
使用婴儿上呼吸道模型比较不同呼吸模式下HFA-BDP和CFC-BDP输送到肺部的剂量。
将具有开放鼻腔气道的9个月大儿童的解剖学正确上呼吸道模型连接到撞击器和呼吸模拟器。通过涂有洗涤剂的小容量储雾罐将100微克的HFA-BDP和100微克的CFC-BDP输送到模型中。在模拟潮气量（VT）为50毫升、100毫升和200毫升且呼吸频率为每分钟30次的潮式呼吸过程中，评估离开模型的总剂量（肺部剂量）、其粒径分布和质量中值空气动力学直径（MMAD）。剂量以标称剂量的百分比表示。
在VT为50毫升、100毫升和200毫升时，HFA-BDP的肺部剂量分别为25.4%、26.5%和30.7%，而CFC-BDP的肺部剂量分别为6.8%、4.8%和2.1%。HFA-BDP输送到肺部的<2.1微米颗粒的剂量为23%至28%，而CFC-BDP为0.6%至0.8%。CFC-BDP的肺部剂量主要由2.1微米至4.7微米之间的颗粒组成。HFA-BDP的MMAD为1.2微米，CFC-BDP根据VT不同为2.6至3.3微米。CFC-BDP的肺部剂量随VT增加而显著降低。HFA-BDP的肺部剂量随VT无显著变化。
在这项婴儿模型研究中，使用含有大量<2.1微米颗粒的HFA-BDP可显著提高输送到肺部的剂量。此外，与CFC-BDP相比，HFA-BDP中大量的超细颗粒导致肺部剂量对呼吸模式的依赖性较小。
