Background: Chlorofluorocarbons (CFCs) have traditionally been used as propellants in pressurized metered-dose inhalers (pMDIs), which are often used to deliver drugs to the lungs for the treatment of reversible obstructive airways diseases. However, CFCs are harmful to the environment and need to be phased out. Hydrofluoroalkanes (HFAs), such as HFA-134a, represent a safe alternative to CFC propellants for use with pMDIs. Formoterol fumarate has been recently formulated in an HFA-134a-containing pMDI and is undergoing clinical testing with the aim of providing an effective, safe and environmentally-friendly alternative to currently existing formulations.
Objectives: The study objective was to demonstrate the non-inferiority (clinical equivalence) of the HFA-134a-propelled formoterol pMDI versus the formoterol Aerolizer dry powder inhaler (DPI).
Methods: The study was a single dose, double-blind, double-dummy, randomized, placebo and reference product controlled, three-periods, crossover trial in 49 patients with moderate-to-severe stable asthma. The active treatments involved a single 12-microg dose of formoterol delivered from an HFA-134a-propelled pMDI and an Aerolizer DPI. The primary efficacy parameter was the average 12-hour forced expiratory volume in 1 s (FEV1), calculated as area under the 12-hour post-morning dose FEV1 time curve divided by time (hours).
Results: Mean 12-hour average FEV1 was 2.28 liters for placebo, 2.60 liters for formoterol pMDI and 2.60 liters for the formoterol DPI. Contrast analysis showed that the HFA-propelled formoterol pMDI was significantly superior to placebo in terms of 12-hour average FEV1. Further statistical analysis confirmed bronchodilation with the pMDI formoterol formulation which was clinically equivalent to that seen with the DPI formoterol formulation. All treatments were well tolerated.
Conclusions: The bronchodilatory effect of a 12-microg dose of formoterol inhaled from a CFC-free, HFA-propelled pMDI is significantly superior to placebo and equivalent to a commercially available formoterol DPI.