An inhaler (puffer, asthma pump or allergy spray) is a medical device used for delivering medicines into the lungs through the work of a person's breathing. This allows medicines to be delivered to and absorbed in the lungs, which provides the ability for targeted medical treatment to this specific region of the body, as well as a reduction in the side effects of oral medications. There are a wide variety of inhalers, and they are commonly used to treat numerous medical conditions with asthma and chronic obstructive pulmonary disease (COPD) being among the most notable. Proper education on inhaler use is important to ensure that inhaled medication creates its proper effects in the lungs. thus providing the most optimal treatment.

Medical uses

Inhalers are designed to deliver medication directly to the lungs through a person's own breathing. This may benefit a patient by providing medicines directly to areas of disease, allowing medication to take a greater effect on its intended target, and limit side effects of medications when administered locally. Two of the most common conditions that warrant inhaler therapy are asthma and chronic obstructive pulmonary disease.

Asthma

Asthma is a condition of intermittent airway obstruction due to inflammatory processes in the lungs. Inhaled medications are used to calm down the inflammation present in the lungs and allow for relief of the airway obstruction. Common inhaled medications used for treatment of asthma include long term inhalational steroidal anti-inflammatory drugs (most commonly inhaled corticosteroids, also called ICS) and fast-relieving bronchodilators such as salbutamol (known commonly as "Ventolin") and salmeterol. These medications allow for patients to have relief of airway obstruction symptoms and reduced inflammation.

Chronic obstructive pulmonary disease (COPD)

COPD is an obstructive lung disease due to long-term damage to the airways of the lungs. The long-term damage leads to the inability of the airways to open properly, causing airway obstruction. Inhaled medications allow patients to see improvement in symptoms and better function of daily living. Some commonly used inhaled medications in patient's with COPD are ipratroprium, salmeterol, and corticosteroids.

Types of inhalers

Meter-dosed inhaler (MDI)

The most common type of inhaler is the pressurized metered-dose inhaler (MDI) which is made up of 3 standard components- a metal canister, plastic actuator, and a metering valve. The medication is typically stored in solution in a pressurized canister that contains a propellant or suspension. The MDI canister is attached to a plastic, hand-operated actuator. On activation, the metered-dose inhaler releases a fixed dose of medication in aerosol form through the actuator and into a patient's lungs. These devices require significant coordination as a person must discharge the medication at or near the same time that they inhale in order for the medication to be effective. This problem is mitigated by the use of a spacer chamber, which allows the fine particle suspension to slow down and be more effectively inhaled into the lower airways . It is preferable that a spacer chamber is used for delivering medication by MDI for all age groups.

Dry powder inhaler (DPI)

alt=|thumb|Different types of [[Dry-powder inhaler|dry powder inhalers]]

Dry powder inhalers release a metered or device-measured dose of powdered medication that is inhaled through a DPI device. This device usually contains a chamber in which the powdered medication is deposited prior to each dosage. The first smart-inhaler was approved in 2019 by the FDA, its purpose is to track patient use of the device and some other circumstantial factors that could affect the effectiveness of the dosage. It shows how effective the device is at aiding patients in using the proper dose amount for their asthma. In a study published by the European Respiratory Journal, the ProAir Digihaler accurately identified when patients were using their inhalers and whether they were effectively administering the dose in a 370 patient trial with the device.

Propellants

In 2009, the FDA banned the use of inhalers that use chlorofluorocarbons (CFC) as propellants. In their place, inhalers now use hydrofluorocarbons (HFCs), which are also called hydrofluoroalkanes (HFAs). HFCs are greenhouse gases, but do not deplete the ozone layer. While some people with asthma and advocacy groups contend that HFC inhalers are not as effective, published clinical studies indicate CFC and HFC inhalers are equally effective in controlling asthma.

While the impact of CFCs from inhalers on the ozone layer had been minuscule (dwarfed by industrial processes using CFCs), the FDA in its interpretation of the Montreal Protocol mandated the switch in propellants. Patients expressed concern about the high price of the HFA inhalers as there were initially no generic versions, whereas generic CFC inhalers had been available. (which involves most of the muscles of respiration, such as external and internal intercostal muscles) during intake of one or more puffs from the inhalers.

Improper use of inhalers is very common, can lead to distribution of the medicine into the mouth or throat where it cannot create its desired effect and may cause harm. Education on the correct use of inhalers for delivery of medications is a commonly cited topic in medical studies and a great deal of thought has been put into how best to help people learn to use their inhalers effectively. Below is a description of proper inhaler technique for each different type of inhaler as well as a helpful video explaining what the text states.

thumb|Using an inhaler

Meter-dosed inhalers

  1. The mouthpiece is removed and the inhaler is shaken for 5–10 seconds.
  2. The inhaler is gripped with mouthpiece on the bottom and canister on top. A finger is placed on the canister to allow for delivery of medicine.
  3. Deep inhalation is done until no more air can be taken into the lungs.
  4. Deep exhalation is done until most of the air is out of the lungs.
  5. Once deep exhalation is done, mouth is placed over mouthpiece.
  6. As the next deep inhalation begins, the canister is pressed down to release the medicine into the lungs.
  7. Slow deep breathing is continued and breath is held for 5–10 seconds, keeping the medicine in the lungs for a longer time period and preventing escape of aerosolized form of the medicine.
  8. Complete exhalation is done again. If multiple puffs of the medicine have to be taken, steps 1–5 are repeated after waiting for 15–30 seconds.
  9. Mouthpiece is replaced. Deep breathing is done to be ready for the delivery of the medicine to the lungs; this minimizes need for coordination of breathing with inhaler activation. Because of high prices, patients sometimes skip doses or give up using their inhalers.

History

thumb|upright|Penetro brand inhaler from mid 20th century Mexico, part of the permanent collection of the [[Museo del Objeto del Objeto]]

thumb|upright|Inhaler designed by John Mudge in 1778

The idea of directly delivering medication into the lungs was based on ancient traditional cures that involved the use of aromatic and medicinal vapors. These did not involve any special devices beyond the apparatus used for burning or heating to produce fumes. Early inhalation devices included one devised by John Mudge in 1778. It had a pewter mug with a hole allowing attachment of a flexible tube. Mudge used it for the treatment of coughs using opium. These devices evolved with modifications by Wolfe, Mackenzie (1872) and better mouth attachments such as by Beigel in 1866. Many of these early inhalers needed heat to vaporize the active chemical ingredient. The benefits of forced expiration and inspiration to treat asthma were noted by J. S. Monell in 1865. Chemicals used in inhalers included ammonia, chlorine, iodine, tar, balsams, turpentine camphor and numerous others in combinations. Julius Mount Bleyer used a variation in 1890 in New York.

thumb|left|upright|Mouthpiece for an inhaler designed by Dr Beigel (1867)

In 1968, Robert Wexler of Abbott Laboratories developed the Analgizer, a disposable inhaler that allowed the self-administration of methoxyflurane vapor in air for analgesia.

Further reading

  • Basics aspects of inhaled pharmaceutical aerosols
  • Recent advances in spray medication technology
  • Discrete simulation of powder dispersion in pharmaceutical aerosol inhalers