Asthma inhaler

Asthma inhalers are devices for treating asthma. They contain an asthma medication--a drug that treats the symptoms of asthma. 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.

Additional recommended knowledge

Essential Laboratory Skills Guide

Correct Test Weight Handling Guide: 12 Practical Tips

Don't let static charges disrupt your weighing accuracy

Until recently, MDI inhalers were filled with CFC as propellant for the medication. The world is currently changing over to halocarbons (HFA) 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 gel capsules containing the powdered medication 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.

See also

• Inhaler