Asthma inhaler
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Asthma inhalers are devices for treating asthma. They contain an asthma medication--a drug that treats the symptoms. The most widely used variety are pressurised aerosols metered dose inhalers (MDI) using a carrier substance to suspend the drug, pressurise the system and carry the drug in particles or droplets of a suitable size to reach the small airways in the lungs.
Until recently, MDI inhalers were filled with CFC as propellant and solvent for the medication. The world is currently changing over to halocarbons for this purpose.
In one variety of beclomethasone inhaler, the combination of increased absorption and better particle size has resulted in an increase of potency of 180%, however for the salbutamol inhalers the effectiveness and dose required remain unchanged.
Other systems involve micronised powder packaged for example in single dose quantities in blisters or compressed pellets and mechanically liberated and suspended and drawn into the lungs by the user's own breath. These systems tend to be more expensive than the MDI, and at the time the user most needs them it may be difficult to generate enough airflow to get good function from them. However, they do not affect the ozone layer.
To increase the amount of drug getting to the lungs, a spacer can be used. The inhaler is puffed into the spacer while the asthmatic breathes normally through the spacer. Plastic spacers have been popular but develop a static charge which leads to a variable amount of the medication sticking to the inside. There is some work on metal spacers going on, these would avoid static.