About inhaler devices
Inhaler devices are designed to help deliver inhaled medication into the airways in the most efficient manner and with minimal loss of medication. Inhaled medication is used for treating, preventing and controlling symptoms of asthma and other chronic respiratory diseases like chronic obstructive pulmonary disease (COPD).
The type of device used depends on the type of medication and delivery mechanism being used and includes:
- Spacer device for use with a metered dose inhaler
- Dry powder inhalation device for use with capsules
Spacer devices for aerosol inhalers
Aerosols, containing respiratory medication and a propellant are generated using a pressurised metered dose inhaler (MDI). These particles are often generated at a faster rate than can be inhaled by the user, as this takes considerable coordination between actuation of the inhaler and inhalation of the aerosol. Poor coordination results in deposition of these particles at the back of the throat, which can cause local side effects, such as yeast infection due to inhaled steroids; also the amount of medication reaching the airways can be reduced if deposited in the throat.
The MDI is attached to one end of the spacer device, which acts as an interface between the patient and the medication, minimising need for coordination with the inhaler. The aerosol medication is delivered into a spacer, which is essentially a tube with a mouthpiece at the other end. A spacer device can also include a valve and this type of spacer is also called a holding chamber, since the aerosol is held in the chamber for longer to allow for controlled deep inhalations from the aerosol cloud within the spacer, which reduces the risk of exhaling into the chamber
The spacer also allows the aerosol to break into smaller droplets before being inhaled, which increases the efficiency of drug delivery into the lungs.
A spacer device can be coated to prevent loss of medication by sticking due to static.
Dry powder inhaler devices
A dry powder inhaler (DPI) is a device for delivering medication directly into the lungs in the form of a small particulate dry powder, without the use of a propellant. The delivery mechanism depends on the force of inhalation and is generally designed to be used with minimal inhalation force.
A device for use with a DPI is available to dispense the contents of a single dose contained within an individual capsule. A capsule must be loaded into the device, which then pierces the capsule releasing the powder containing the medication for inhalation. This form of delivery is activated by inhalation and therefore, less coordination is needed. When the contents of a capsule have been inhaled, the capsule must be removed from the device before another capsule can be loaded.