Nonchlorinated propellants to replace CFCs have been developed and consist of hydrofluoroalkanes (HFAs) . These are less reactive and persist in the atmosphere for a much shorter time than CFCs. 3M is the only company, to date, to bring to market a pMDI using an HFA type propellant. This is only recently available in Canada, and our experience with this product is therefore quite limited. Information published or presented at scientific meetings thus far suggest that this device provides much improved drug delivery to the lungs in the case of the inhaled corticosteroid be-clomethasone, with 50% or more reaching the airway compared with approximately 25% to 30% in the case of the traditional pMDI attached to a large volume spacer. Delivery of the beta-agonist albuterol is approximately equivalent without a spacer but increased when such a device is attached . A smaller delivered volume may again worry patients about whether they are receiving an adequate dose. In addition to improved delivery of inhaled corticosteroids, the 3M inhaler provides less acute bronchospasm (‘cold freon effect’), and there is less variation of dose with storage and exposure to cold temperatures .
Category: Inhaled drug
Tags: Aerosols, Asthma, COPD, Drug therapy
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