The continued need for metered dose inhalers.

The metered dose inhaler (MDI) is currently the most widely used device in the treatment of adult asthma. It is the delivery system of choice in general practice throughout the world where both MDIs and powder inhalers are available. Up to 70% of all UK adult asthma prescriptions are for an MDI and worldwide the figures are likely to be higher. The MDI can be used to dispense a variety of medications and is currently the most economical device available. The cost of converting all MDIs to equivalent powder inhalers would be prohibitive. Patients, who have difficulty coordinating the operation of an MDI, can use it with a spacer device. This obviates the need for hand-lung coordination and the requirement for more than minimal inspiratory effort. In acute attacks, there is currently no alternative to an MDI with a spacer device for effective, easily administered, emergency treatment outside the hospital environment. In an emergency, an MDI with a spacer can act more rapidly than a nebulizer because it is quicker to set up and use. The MDI is inexpensive, requires no power source and is easily portable. It is therefore important that the MDI continues to be available.