In vitro comparison of two delivery devices for administering formoterol: Foradil P and formoterol ratiopharm single-dose capsule inhaler.
Formoterol, a long-acting beta (2)-agonist with a rapid onset of bronchodilation, is available in various delivery devices. However, differences in the size and uniformity of drug particles generated by different devices may result in variable clinical effects. The present study compared in vitro the aerodynamic particle size distribution, emitted dose and device resistance of formoterol delivered via Foradil Aerolizer (Foradil P) with those a non-proprietary single-dose capsule inhaler (ratiopharm), using an 8-stage Andersen Cascade Impactor set at a flow of 60 L/min. Relative to the formoterol ratiopharm capsule inhaler, Foradil Aerolizer produced particles with a smaller mass median aerodynamic diameter (3.5 vs. 4.1 microm, p = 0.018) and a smaller measured particle diameter distribution (geometric standard deviation 2.2 vs. 2.5, p = 0.048). The Foradil Aerolizer produced a 44% higher fine particle dose than the single-dose capsule inhaler (2.6 vs. 1.8 microg, p = 0.0001). Although the single-dose capsule inhaler produced a higher total emitted dose than that from Foradil Aerolizer (11.2 vs. 10.0 microg, p = 0.155, not significant), the respirable fraction from Foradil Aerolizer was 58% higher (25.7 vs. 16.3%, p = 2 x 10(8)). Both devices had a similarly low airflow resistance. These relative particle size profiles suggest that the Aerolizer may provide a more clinically effective delivery of formoterol to the lungs at the high inspiratory flows such as are typically achieved using this device.