Aerosol devices and asthma therapy

Aerosol delivery of asthma medications maximizes local effects in the lung and minimizes systemic effects compared with oral therapy. Both corticosteroids and bronchodilators are available in a variety of delivery devices for the treatment of asthma. The 1987 Montreal protocol requiring the phasing out of the chlorofluorocarbon (CFC) propellant in commonly used pressurized metered-dose inhalers (pMDIs) provided an impetus for the development of new technologies for the delivery of inhaled asthma medications. For pMDIs, CFC has been replaced with hydrofluoroalkane (HFA) propellant. New types of dry powder inhalers (DPIs) and nebulizers, aerosol delivery devices that do not use propellants, also have been introduced. Drug delivery varies based on the device type, the product formulation and patient-related factors. Thus, drug delivery can differ when the same medication is delivered via an HFA pMDI, a CFC pMDI, a DPI or a nebulizer. Even among the same type of device (eg. DPIs, pMDIs), inhaler designs and drug formulations differ. Drug and device selection should be based on consideration of the patient's ability to use the device properly, the availability of a desired drug or drugs (ie. maintenance and rescue) in a particular inhaler device and patient preference. This review describes key characteristics for each device type, explains differences in markers of lung deposition, lists potential advantages and disadvantages of the different devices and discusses how these and other factors need to be considered when selecting an inhaler device that meets the individual needs of a patient.