Faculty of Pharmacy, University of Maiduguri, Maiduguri, PMB 1069, Nigeria.
Int J Pharm. 2013 Oct 15;455(1-2):213-8. doi: 10.1016/j.ijpharm.2013.07.036. Epub 2013 Jul 24.
An interaction between device resistance and inhalation flow provides the 'energy' to de-aggregate the metered dose of dry powder inhalers (DPIs). Hence all dry powder inhalers demonstrate flow dependent dose emission but information on this at low flows is not available. We have adapted the compendial method for the Andersen Cascade Impactor (ACI) to include a mixing inlet to determine the aerodynamic dose emission characteristics of a salbutamol Diskus(®) [DSK], Easyhaler(®) [EASY] and Clickhaler(®) [CLICK] and the terbutaline Turbuhaler(®) [TBH] using flows of 10-60 L/min and inhalation volumes of 2 and 4 L. All DPIs demonstrated flow dependent dose emission (p<0.001) but there was no difference in the measurements between 2 and 4 L. The flow dependent dose emission properties of each DPI started to plateau when the pressure change inside each device, during an inhalation, was between 1 and 1.5 kPa. This corresponds to inhalation flows of 40.1-49.1, 25.4-28.9, 23.6-28.9 and 29.7-36.3 L/min through DSK, CLICK, EASY and TBH. The adapted methodology allows measurements at low flows. The results highlight that the compendial methodology to use an inhaled volume of 4 L with the ACI could be replaced by 2 L and that the recommendation to make measurements using a pressure drop of 4kPa should be revised.
装置阻力与吸入气流之间的相互作用为干粉吸入器（DPI）的定量药物提供了“能量”以使其解聚。因此，所有干粉吸入器都表现出与流量相关的剂量释放，但在低流量下的相关信息尚不清楚。我们对用于 Andersen 级联撞击器（ACI）的药典方法进行了改编，包括一个混合入口，以确定沙丁胺醇 Diskus（®）[DSK]、Easyhaler（®）[EASY]和 Clickhaler（®）[CLICK]和特布他林 Turbuhaler（®）[TBH]的空气动力学剂量释放特性，使用 10-60 L/min 的流量和 2 和 4 L 的吸入量。所有 DPI 均表现出与流量相关的剂量释放（p<0.001），但 2 和 4 L 之间的测量值没有差异。当每个装置内的压力变化在吸入过程中在 1 到 1.5 kPa 之间时，每个 DPI 的与流量相关的剂量释放特性开始趋于平稳。这对应于 DSK、CLICK、EASY 和 TBH 通过的吸入流量分别为 40.1-49.1、25.4-28.9、23.6-28.9 和 29.7-36.3 L/min。改编后的方法允许在低流量下进行测量。结果表明，使用 ACI 吸入 4 L 体积的药典方法可以用 2 L 体积代替，并且应该修改使用 4kPa 压降进行测量的建议。
