What are different types of Asthma inhalers
One type of asthma treatment is the use of asthma inhalers, or handheld devices that deliver medication to the lungs. There are a variety of different inhalers, each with their advantages and disadvantages, and certain types may work better for some people than others.
Inhalers can be classified into two categories: Metered dose inhalers (MDIs) and Dry powder inhalers. Metered dose inhalers are usually used as asthma rescue inhalers or reliever medicines. There are breath-actuated autohalers such as pirbuterol acetate (ex. Maxair Autohaler), which releases the medication when you breathe in, and there are non breath-actuated pressurized inhalers such as albuterol sulfate (ex. ProAir-HFA) in which the medication is released by pushing the canister down into the holder. HFA stands for Hydro Fluoro Alkane and because the FDA has banned the use of Chloro Fluoro Carbon (CFC) based propellants, companies have started using HFA based propellants instead.
Some MDIs can be used with a spacer or have a built in spacer which holds the medication after it’s released so it can be inhaled slowly. Some have counters that keep track of how many doses remain and for some there is no counter making it more difficult to know when the inhaler is low on medication. A picture of each is shown below:
This is an image of Maxair which is used by lifting up the tab at the top of the inhaler to deliver the dose, then breathing in to release the medication.
Non breath-actuated pressurized inhaler:
This is an image of ProAir HFA which is used by pushing the canister down into the device while simultaneously breathing in the medication.
Metered dose inhalers contain different types of medication. There are short acting beta agonist inhalers such as ProAir, Maxair, and Xopenex. These inhalers are used as rescue inhalers and they provide quick relief by opening the airways. They are best used for treating sudden asthma attacks but they can also be used before exercise for those who suffer from exercise-induced asthma. There are also long acting beta agonist inhalers (LABA) such as Serevent and Foradil and these inhalers provide asthma control and should never be used as a rescue inhaler. They can be used with inhaled corticosteroids (ICS) such as Azmacort, Pulmicort, and Qvar for long-term control of asthma symptoms. There are also inhalers such as Advair HFA and Symbicort that are a combination of LABA and ICS and are used for patients with more chronic asthma that is not controlled with other medications. Other drugs like ipratropium (Combivent, Atrovent) etc are also available in MDI forms. All of these inhalers are bronchodilators.
The primary advantage of MDIs is that the propellant pushes the drug into the initial bronchi, providing asthma relief. They are also small and convenient to carry around and accidentally breathing out a little while using will not cause a problem in the delivery of the medicine. The primary disadvantage is that you must coordinate your breath with the release of the medication though this can be alleviated to some extent by the use of autohalers. Another disadvantage to using MDIs is that medication can settle in the back of the throat and tongue though this can also be corrected slightly with the use of a spacer. There is still, however, a chance that patients may commit a critical error and not receive any medicine at all due to the improper use of an inhaler.
Another class of inhalers is dry powder inhalers (DPIs). These are a group of inhalers that have the medication in very fine dry powder format. They are classified into single dose devices, multiple unit dose devices and multi dose devices. These tend to be more popular with patients because they are breath actuated.
Single dose devices such as a Handihaler, Rotahaler, Aerolizer etc. require the patient to insert a dose of medication into the device before inhaling. For example Spiriva Handihaler, though commonly used as a chronic obstructive pulmonary disease (COPD) inhaler it is also occasionally used for asthma treatment and it involves inserting a capsule into the device, pressing a button on the device that pierces the capsule, then breathing in the powder contained in the capsule through the mouthpiece.
Multiple unit dose devices contain multi dose blister packs coiled inside the inhaler that are to be punctured before inhalation. An example of this is Relenza Diskhaler which is used for allergic rhinitis:
Multidose devices such as a Diskus (Accuhaler), Tubuhaler (Twisthaler), and Flexhaler contain all the doses in a reservoir and it is delivered after proper inhalation. An example of this is the Advair Diskus:
A primary advantage of dry powder inhalers is that the user doesn’t need to coordinate breath with medication release and minimal inspiratory force is required to use this medication. There is also a dose indicator allowing one to keep track of how much medication is left in the device. The primary disadvantage is that the medication can settle in the back of the throat and tongue and this can cause oral thrush (candidiasis). There is also usually an aftertaste caused by dry powder inhalers and each type of dry powder inhaler has specific inhaler usage instructions.
There are many different types of inhalers that are used for asthma treatment and the one a patient chooses depends on the severity of their asthma, personal preference, or whether the patient is in need of rescue medication or more long-term asthma control.