Asthma is a chronic condition of the airways which is characterized by coughing, wheezing and difficulty in breathing. It is a condition of relapses and remissions. An acute attack, when severe is a medical emergency and requires prompt and immediate treatment. Devices have been developed which can be carried by the patient on his person and used to deliver the drug directly to the airways so that immediate opening of the airways can occur facilitating breathing. The following are common asthma medication delivery devices:
An asthma inhaler is a handheld device that delivers asthma medication straight into the airways.
Advantages of an asthma inhaler:
1. More of the drug can directly reach the airways.
2. Fewer side effects occur from the drug.
3. Some drugs are effective only when taken in an inhaled form.
The following are different types of inhalers:
1. Metered dose inhalers
2. Dry powder inhalers
These devices are used to deliver the following drugs:
2. Mast cell stabilizers
Metered Dose Inhalers (MDIs)
The metered dose inhaler is a pressurized canister of medicine in a plastic holder with a mouthpiece. It sprays a reliable fixed amount of medication so an accurate dosage can be maintained.
Method of use:
1. Remove the cap from the MDI and shake well.
2. Breathe out completely and place the mouthpiece between your teeth and close your lips tightly around it.
3. Press the canister once and breathe in slowly and completely through your mouth.
4. Hold your breath for 10 seconds to allow the medication to reach the airways of the lungs.
5. Take the required number of puffs as advised by your doctor with an interval of one minute in between puffs.
The number of puffs contained in the MDI is printed on the side of the canister. Once it is over, the MDI should no longer be used even if it continues to spray.
Dry Powder Inhalers (DPIs)
The dry powder inhaler is a device that delivers medication to the lungs in the form of a dry powder. The medication is usually held in a capsule form inside the inhaler.
The inhaler is put in the mouth and the patient is asked to take a deep breath. The breath is held for five to ten seconds. Most DPIs rely on the force of the patient's inhalation to break the powder into tiny particles which can be delivered to the lungs. Thus, it is difficult to use in case of very small children or persons who have reduced lung capacity as they have less force of inspiration. DPIs are mostly used in older children and adults.
Nebulizers are machines that transform liquid medication into a fine mist/droplet form which can be inhaled deep into the airways. Nebulizers are beneficial when a large dose of drug has to be delivered to the lungs. They are also useful in patients who cannot use the above inhalers effectively.
Asthma medication delivery devices help in rapid and efficient delivery of the drug into the lungs. Different devices are used in different conditions according to the requirement as well as the age and health of the patient.
1. Current review of asthma by Kaliner M. Current Medicine,Inc, 2003.
2. Gibaldi's drug delivery systems in pharmaceutical care by Gibaldi Milo, Lee Mary, Desai Archana. American Society of Health-System Pharmacists, 2007.