Introduction and objectives Despite differences in actuator resistance between pressurised metered dose inhalers (pMDIs), ‘inhale deeply and slowly’ remains universally recommended for drug delivery. Training aids to tutor inspiratory flow rate are vulnerable to resistance effects and can lead to patient error under a misconception of corrected technique. Actuator mouthpiece design can also limit availability of suitable training devices. Using the Flutiform low-resistance pMDI (Napp Laboratories Ltd), we describe here the development and testing of a suitable training aid based on the audible tone Flo-Tone trainer (Clement Clarke).
Methods Flutiform 5 µg formoterol fumarate/125 µg fluticasone propionate (4.5/115 µg ex-actuator respectively) was assessed via the Next Generation Impactor (NGI) operated at 30 L/min, alone, and together with machined (Ma) or moulded (Mo) mouthpiece adaptors attached to the commercially available Flo-Tone (FTc), anti-static plastic Flo-Tone (FTas), or an abbreviated version (FTab). All least three replicates of each were completed. Drug recovery (µg) from the actuator, adaptor, Flo-Tone, induction port and NGI was determined. The key aerosol performance parameters Fine Particle Fraction (FPF,% <5 µm) and Fine Particle Dose (FPD, µg <5 µm) were determined.
Results Formoterol and fluticasone drug delivery data trends were the same. Here we report the fluticasone data. Drug mass recovery (Figure 1) indicated that the moulded mouthpiece adaptor with abbreviated Flo-Tone (Mo-FTab) approximated most closely to Flutiform drug delivery without a training aid. All prototypes showed reduced throat (induction port) deposition. FPF% and FPD µg data for all prototypes, respectively, were: Flutiform alone, 44.8, 46.9; Ma1-FTc, 36.7, 37.3; Ma2-FTc, 33.1, 34.5; Mo-FTc, 36.0, 38.0; Mo-FTas, 34.4, 36.9; and Mo-FTab, 44.6, 46.4.
Conclusions This process has shown that it is possible to tailor an existing audible training aid to a specific pMDI, enabling an audible training tone at an appropriate inspiratory flow rate without drug delivery compromise. We are currently extending this design-development research to create a standardised device suitable for a range of pMDIs in popular use and that vary in actuator resistance.