Establishment of relationships between native and inhalation device specific spirometric parameters as a step towards...

Drug emission from DPIs is dependent on the inspiratory flow parameters through them, which are not directly measured by standard spirometry. Their estimation based on native spirometric data could help in choosing the appropriate device and optimizing the drug deposition.

The aim of this study was to survey patient preferences and to find correlations between breathing parameters of COPD patients through DPI devices and their baseline spirometric data, age, gender, disease severity and anthropometric characteristics. Another objective was to establish relationships between peak inspiratory flows (PIF_dev) through Breezhaler^®, Genuair^® and Turbuhaler^® inhalers and their determinants.

Breathing parameters of 49 patients with previously diagnosed COPD and currently using one of the above inhalers were recorded by normal spirometry and while inhaling through the selected DPIs. Statistical analysis of the measured data was completed. All specific data are provided as (mean ± standard deviation).

More than 60% of the patients stated that their current device is the easiest to use. The means of the measured PIF_dev values were 91.4 L/min, 77.1 L/min and 77.5 L/min for Breezhaler^®, Genuair^®, and Turbuhaler^®, respectively. PIF_dev values were significantly higher for males than for females, but differences upon age, BMI and disease severity group were not significant (at p = 0.05). Peak inspiratory flows through the inhalers (PIF_dev) correlated best with their native spirometric counterparts (PIF) and linear PIF_dev-PIF relationships could be determined (Breezhaler^®: r = 0.60, p = 0.002, Genuair^®: r = 0.55, p = 0.001, Turbuhaler^®: r = 0.57, p = 0.002). Physical background of the deduced equations was also provided.

Present correlations may be used to assess the success of inhalation of COPD patients through the studied devices and to choose the appropriate device for each patient. As a consequence, the amount of the drug emitted by the device can be optimized, the deposition efficiency within the lungs increased and the related therapeutic effect improved.