Asthma is a chronic lung disease that causes symptoms such as coughing, wheezing, chest tightness and difficulty breathing. There is no cure for asthma, but its symptoms can be controlled and treated with medication. Drugs that treat asthma are usually delivered via inhaler, which releases compressed liquid medication in a fine mist that can be inhaled directly into the lungs. There are a few types of inhalers that deliver medication for the treatment of asthma symptoms.
HFA Inhalers
Metered dose inhalers are a class of inhaler that compresses liquid medication in a metal canister. The plastic housing of the inhaler allows the canister to be depressed, releasing the medication in a fixed dose. A substance is mixed with the medication to act as a propellant, which transforms the compressed medication into a fine mist. The Federal Drug Administration (FDA) reports that asthma inhalers currently use hydrofluoralkanes (HFAs) as the propellant of choice. HFAs are environmentally friendly, and they do not contribute to the degradation of the ozone layer.
CFC Inhalers
CFC inhalers are another type of metered dose inhaler. Inhalers sold before December 31, 2008, used chlorofluorocarbons (CFCs) as a propellant. Though CFCs were safe for inhalation, and acted as a efficient propellant, the FDA instituted the phasing out of CFCs in inhalers because they contribute to the depletion of the ozone layer. This was done according to an international agreement cited by the FDA, called the "Montreal Protocol on Substances that Deplete the Ozone Layer."
Inhaler with a Spacer
The Mayo Clinic reports that metered dose inhalers are sometimes used with a spacer, which is a plastic reservoir that is attached to the inhaler and holds the medication after it is released from the canister. Using an inhaler with an attached spacer makes it easier to inhale the entire dose of the medication. Without using the spacer, the medication is propelled at such a high velocity that a significant portion of it can stick to the back of the throat, especially if the inhaler is inserted too far into the mouth during use. The Mayo Clinic says that some inhalers have built-in spacers; others have spacers that can be detached.
Inhaled Powder
Another type of asthma inhaler is a plastic canister that stores the medication in the form of a powder in separate "blisters," and each blister holds an exact dose of medication. When the inhaler is operated, the drug is released from one blister and inhaled. GlaxoSmithKline is the maker of the Advair Diskus, which is one such inhaler that delivers salmeterol and fluticasone propionate powder mixed together in one dose. This type of inhaler does not contain a propellant.
References
- The Federal Drug Administration (FDA): Transition from CFC Propelled Albuterol Inhalers to HFA Propelled Albuterol Inhalers
- The Mayo Clinic: Asthma Inhalers: Which One's Right For You?
- GlaxoSmithKline: Complete Prescribing Information and Medication Guide for ADVAIR DISKUS® (Fluticasone Propionate and Salmeterol Inhalation Powder)
