The impending disappearance of conventional CFC propelled pMDIs will require physicians to switch a large number of patients to other delivery devices. At this time it appears wise to choose one of the newer devices for patients whose therapy is being initiated and patients who require changes in their current asthma therapy. This will allow busy asthma practices to spread out the very substantial educational effort that will be required over the next several years. Not only will patients need to acquire new skills, they will also have to be reassured about the safety and efficacy of the newer formulations .
Choosing an equivalent dose when switching patients who are well controlled on a given dose of inhaled corticosteroid to a non-CFC pMDI or to one of the newer multidose DPIs will be beset with uncertainty. Equivalent doses are likely to vary from patient to patient and in the same patient if, as commonly occurs, inhalation technique changes over time. A simple rule of thumb might be to decrease the dose of inhaled corticosteroid by half for the same medication (usually beclomethasone) when switching from a traditional pMDI to the new 3M non-CFC pMDI. Similarly the dose should be cut in half when changing to budesonide via Tur-buhaler. If the patient has been using a large volume spacer on a regular basis, a similar dose should be prescribed . This process is made all the more difficult by the availability of a large number of inhaled corticosteroids for which equivalent doses are uncertain and likely to be significantly affected