Emitted dose and lung deposition of inhaled terbutaline from Turbuhaler at different conditions

SummaryTurbuhaler has a very high resistance hence patient inhalation flow when using it would be low.The total emitted dose (TED) of 500μg terbutaline sulphate from a Bricanyl Turbuhaler was determined using a range of inhalation flows (10–60L min−1) with inhalation volume of 2 and 4L using a DPI sampling apparatus after one and two inhalations.The relative lung and systemic bioavailability of terbutaline from Bricanyl Turbuhaler when used by healthy subjects and COPD patients were determined after one and two inhalations at slow and fast inhalation flows using a novel urinary terbutaline pharmacokinetic method.The TED resulted from the one and two inhalations increased significantly (p<0.05) with the increase of the inhalation flow at both 2 and 4L inhalation volumes. The relative lung and systemic bioavailability after one inhalation at fast inhalation flow were significantly higher (p<0.01) than at slow inhalation flow in both healthy subjects and patients. Also the healthy subjects results were significantly higher (p