Exhalation immediately before inhalation optimizes dry powder inhaler use

Abstract

Objective: Although exhalation immediately prior to inhalation (EPI) from dry powder inhalers (DPIs) is universally advised, its benefit has not been investigated. The objective of this study to assess the effects of EPI on inhaled flow from a DPI. Methods: We measured peak inhaled flow rate (PIFR) and inhaled gas volume of 25 volunteers unfamiliar with DPIs. They inhaled strongly and deeply through a flow meter either with or without EPI before and after connecting Turbuhaler® or Diskus®. Results: Median PIFR increased significantly with EPI both without connection to DPIs (178.8 versus 140.4 L min⁻¹), and with connection to Diskus® (75.6 versus 67.8 L min⁻¹), or to Turbuhaler® (51.0 versus 48.0 L min⁻¹). As a result, the number of subjects whose PIFR exceeded 60 L min⁻¹ was significantly increased with connection to either Diskus® (76 versus 64%) or to Turbuhaler® (24 versus 4%). EPI significantly increased median inhaled volume both without connection to DPIs (2.84 versus 1.84 L), and with connection to Diskus® (1.95 versus 1.66 L), or to Turbuhaler® (1.86 versus 1.28 L). EPI significantly increased F_0.2 (flow at 0.2 s after onset of inhalation) and AC₃₀ (flow acceleration at 30 L min⁻¹), parameters representing the rate of flow increase during the early phase of inhalation, in all the three groups. Conclusions: EPI increases PIFR which may augment drug dispersion and facilitate fine particle generation from a DPI.

• Chronic obstructive pulmonary disease
• drug delivery
• handling
• inhalation therapy
• peak inspiratory flow

Acknowledgements

The authors gratefully appreciate Dr. Stanley M. Cassan for his critical review of this manuscript.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.