A DEVICE FOR OVERCOMING DISCOORDINATION WITH METERED-DOSE INHALERS

Background: Despite widespread acceptance of metered-dose inhalers (MDIs) in the treatment of asthma, many patients fail to operate these devices correctly. Inability to properly coordinate activation with onset of inhalation is regarded as the major factor in suboptimal MDI therapy. Methods: We evaluated Autohaler Inhalation Device (3M Pharmaceuticals, St. Paul, Minn.), a breath-activated MDI that is typically activated at a triggering flow rate of approximately 0.5 L/sec. We compared bronchodilator effect of pirbuterol acetate (Maxair), inhaled from Autohaler and a standard MDI, under conditions that ensured optimal technique in 20 patients with asthma. Spirometric variables (forced expiratory volume in 1 second [FEV1], forced expiratory flow between 25% and 75% of vital capacity [FEF25-75], forced vital capacity [FVC]) were measured before and at 15, 30, 60, and 90 minutes after two inhalations of full inspiratory reserve volume for each device. Results: Both devices produced significant and similar bronchodilation. Mean FEV1 increased 32% above baseline 60 minutes after use of Autohaler and 31% after use of a standard MDI. Similar changes were noted in FEF25-75 and FVC for the two devices. Differences between devices for all spirometric variables were not statistically significant. Conclusion: Autohaler provides a promising alternative to the standard MDI by overcoming breath-hand discoordination.