An inhaler is a device that delivers respiratory medication in aerosol form. The modern inhaler has undergone a number of modifications and design revolutions in the seven decades since it was first introduced. The following are delivery methods that have been or are currently used for the treatment of asthma or COPD.
Metered dose inhalers (MDIs)
The the most common inhaler device is called the Metered Dose Inhaler (MDI). It consists of a canister that holds the medication. The inhaler contains a liquefied gas that is used as the propellant to deliver the medication upon inspiration. The device has a mouthpiece with an actuator atomizer that can deliver a consistent amount of medication with each puff.
The first MDI was developed in 1956, by California-based Riker Laboratories, which was acquired in 1970 by what is now the pharmaceutical company, 3M Northridge. The original inhalers used a propellant technique — developed by a perfume company, incidentally — containing chorofluorocarbons (CFCs), which are volatile derivatives of carbon gases. Because of their efficiency of delivery, portability, and low cost, inhalers became very popular.
The type of propellants used in MDIs have since changed. Chlorofluorocarbons were banned in 2009 because they were deemed harmful to the environment. They were replaced by hydrofluoroalkanes (HFAs).
Still, there have been some issuess with these inhalers. They are not always easy to use and the effectiveness of the dose depends on the reliability of the user. In addition, the anatomy of the mouth and throat vary with each individual. So, in spite of the same amount of medication being delivered with each inhalation from the device, there is no guarantee that this amount would actually enter the lungs.
For a long time, this was the only device that was available, and despite recognition of the device flaws, the only changes in treatment are the medications being delivered.
Dry powder inhalers
Glaxo Smith Kline (GSK) introduced the first dry powder device in the form of a round disc, which made it easier to put in one’s pocket. This device contained the medicine in a capsule that would break upon activation, and a consistent dose of the medicine would be delivered during inhalation. This device would not have a propellant and it would be up to the user to inhale all the particles of the medication.
This new type of inhaled medication posed a problem for individuals with severe lung disease who did not have the strength needed to inhale the dry powder. It was also not suitable for children.
The use of dry powder and capsules containing specific doses have continued to evolve with a new device designed by Glaxo Smith Kline (GSK). GSK holds a patent on the device as well as on the medication. This inhaler device is called Ellipta. It’s smaller, easier to transport and it can stand on a table. The benefits and the challenges of delivery are still similar to earlier devices.
This is my personal favorite since seems easier for the patient to inhale. Use of the device doesn’t require strong effort, so it’s convenient for individuals with severe chronic lung disease whose breathing effort is likely weakened. It also doesn’t have the irritating effect of the solid particles associated with dry powder. It does require hand-mouth coordination which may be an issue for some elderly patients.
There are also “smart inhalers” that use electronic monitoring to track use of these devices.
The nebulizer seems to be the most effective method of medication delivery since it’s done over a period of several minutes - not in one breath or puff like the previously discussed inhalers. The nebulizer medication comes in liquid form, and it’s placed in a container. The nebulizer is connected to a source of air which converts the liquid into aerosol mist that is inhaled over 10 to 15 minutes. There’s no propellant and there’s the additional advantage that the nebulized solution also helps to liquefy the secretions remaining in the lung, making it easier to cough and bring them up.
Nebulized treatments are frequently used for hospitalized patients with pneumonia and COPD exacerbation, conditions where the goal is to help mobilize secretions and not to simply treat asthma. It’s also used in emergency rooms for acute respiratory care. Another psychological benefit is the effect on the patient who believes that he is getting more “complete” treatment.
The disadvantage of nebulized treatment is lack of portability and the skillset required to set it up.
The use of a nebulizer opens the possibility of mixing many other medications and tailoring treatment by need rather than being restricted by what’s in the standard inhalers. It also helps avoid the scenario of having people using different inhalers to get control of more complicated respiratory disease.
Moving from devices to medications
The medications for asthma can be divided into 2 groups: rescue medications and controller medications.
Rescue Medications include:
Albuterol, which can be given through metered dose inhalers or through nebulizer treatments. It’s the most popular medication and includes brand name Pro Air, Proventil, and Ventolin.
Xopenex contains levalbuterol, one of the isomers of albuterol (isomers are chemical compounds whose structures are mirror images of each other).
Controller medications include:
Long-acting bronchodilators (LABA), whose actions are similar to albuterol the rescue medication, but with a long-lasting effect. They include the drugs salmeterol and formoterol.
Inhaled corticosteroids (ICS) which are recommended as first line treatment when controller medications are needed, per current guidelines.
Long-acting muscarinic agents (LAMA) open the bronchi through a different mechanism. They are especially helpful in COPD as opposed to asthma. The first one was tiotropium, brand name Spiriva.
- Spiriva is the first LAMA once-a-day medication for COPD in Respirmat mist form.
- Stiolto is a combination of Tiotropium (Spiriva) and an LABA, Oldaterol.
- Striverdi offers the LABA, oldacaterol, in a Respimat mist form.
- Symbicort, popular because it's covered by most insurances. It's a combination of an inhaled steroid and a LABA (formoterol).
- Bevesty is a newer offering of an LABA/LAMA combination. The LAMA called glycopyrrolate Is supposed to cause less dry mouth, a common complaint with the other mist devices that use an LAMA.
Note: Both come in a metered dose inhaler with an actuator activated by the inspiration of the user so it's not necessary to coordinate the puff with the breath effort.
- Dulera, a combination of inhaled steroid and an LABA.
- Trelegy Ellipta is a new medication that actually includes the three drugs - LABA, LAMA and an inhaled steroid in one device. It’s triple drug combination has made it a very popular option and I expect other companies to follow suit and develop their versions of triple drug mist systems.
The treatment of asthma is dynamic and patients need to accept that there may be need to be change their regimens at different times to address different situations. That’s why patient need to seek a specialist who can personalize their treatment regimen “as needed.”