Asthma is a common chronic lung condition that causes difficulty breathing. The Centers for Disease Control and Prevention (CDC) estimate that over 7 percent of adults and over 9 percent of children in the U.S. have asthma. There are several different types of medication prescribed to treat the symptoms of asthma, which are often packaged in inhalers. Inhalers deliver the medication in a fine mist, which can be inhaled directly to the lungs.
Metered-Dose Inhalers
A metered-dose inhaler administers many types of drugs that treat asthma symptoms. This type of inhaler packages the drug in a metal canister that fits inside a plastic housing. When the metal canister is depressed a metered (fixed)-dose of the drug is release through the mouthpiece, and the drug is inhaled into the lungs. It is important to use metered-dose inhalers properly so that the correct dose of the drug is administered. MedlinePlus, an online medical encyclopedia sponsored by the U.S. National Library of Medicine, advises "priming" the inhaler a couple of times before the first use, or if it has not been used for several weeks. To prime the inhaler, the inhaler is shaken and the canister is depressed with the mouthpiece pointed away from the person. Because the drug is in liquid form, a propellant is needed to transform the drug into a fine mist to be inhaled. The Federal Drug Administration (FDA) reports that HFA (hydrofluoralkane) is now the chemical propellant of choice. CFCs (chlorofluorocarbons) used to be used as a propellant, but have been phased out as of December 31, 2008 because they deplete the ozone layer.
Metered-Dose Inhalers With Spacer
Some metered-dose inhalers have fixed spacers attached to the mouthpiece or have spacers that can be attached and removed. The Mayo Clinic describes spacers as plastic reservoirs that hold the medication once it is released from the inhaler. It allows the person inhaling the medication to inhale more slowly, which makes it more likely that a full dose is administered. Spacers are also helpful because they decrease the amount of the drug that sticks to the back of the throat as a result of the medication being sprayed at high speed from the mouthpiece.
Dry Powder Inhalers
Asthma medications are also offered in the form of a dry powder rather than an aerosolized liquid. Dry powder inhalers hold the power in a blister that is released into a chamber by pulling back a lever on the inhaler. The Mayo Clinic adds that the medication is then delivered to the lungs not by a chemical propellant, but by a deep breath that pulls the powder from the chamber, through the mouthpiece, into the lungs. However, breathing out before inhaling can blow away the powder before it is inhaled.
References
- The Centers for Disease Control and Prevention (CDC): Asthma Faststats
- The Mayo Clinic: Asthma Inhalers: Which One's Right For You?
- The Federal Drug Administration (FDA): Public Health Advisory - National Transition from Chlorofluorocarbon (CFC) Propelled Albuterol Inhalers to Hydrofluroalkane (HFA) Propelled Albuterol Inhalers
- MedlinePlus: How to Use Metered-Dose Inhalers
