Twenty years ago when I learned about COPD (chronic obstructive pulmonary disease) in pharmacy school, the focus was on smoking cessation. There were limited inhaler options back then; we only had salbutamol (Ventolin) and ipratropium (Atrovent) as metered dose inhalers. My impression at the time was that COPD should be prevented if at all possible because the treatment options were limited. Actually, I felt the inhalers were useless craps.
Taking medication by inhalation is actually quite complicated. The efficacy is affected by:
- The particle size of the medication,
- The speed at which the inhalation occurs,
- The coordination between the release of medication from the device and the actual breath of inhalation, and
- Any existing lung pathology such as pulmonary fibrosis.
Often times, a lot of the medication get lost in transit. Poor technique can contribute greatly to poor delivery of the medication and as such, there is so much emphasis on education and ensuring the correct technique is applied when using the inhalation device.
Recently, there have been many advances on the design of inhalation devices, allowing many options for patients to choose from based on different needs (e.g. convenience, cognition, dexterity). However, they can be categorized into three main types of inhalers:
- Metered Dose Inhalers
- Dry Powder Inhalers
- Soft Mist Inhalers
Metered Dose Inhalers (MDIs) are the first type of inhaler available for use. The medication is suspended with a propellant which allows the medication to travel at a fast pace to be inhaled into the lung.
However, it is incredibly difficult to have perfect hand-breath coordination and as such, a spacer device is recommended to be used with this type of inhaler. A spacer is a device which allows the medication to be trapped in a chamber and allow the patient to breathe in the medication at his or her own pace. A space with a one way valve will ensure the medication will only travel in the direction of the patient’s mouth. For adults, it is recommended to use a spacer with a mouthpiece. However for individuals unable to form a close seal with the mouthpiece, a space with a face mask may be used.
There are other disadvantages with the metered dose inhalers. Many require priming with first use and subsequent use if it hasn’t been used for awhile. The older ones do not have a dose counter or a reliable way to detect whether the inhaler is empty or not.
Dry Powder Inhaler is the second generation inhaler. The medication is made in the form of dry powder. The inhalation device often needs to be loaded before it can be inhaled. . The device should not be exposed to moisture and optimal delivery often requires forceful inhalation which may not be easy for individuals with advanced COPD or shallow breathing. There are currently various devices available; some are designed with convenience in mind (Ellipta), others with features such as dose counter to recognize when the device is empty (e.g Turbuhaler, Genuair, Ellipta). And many have different methods of loading the dose from inserting a capsule (e.g. Handihaler, Breezhaler), twisting the base (e.g. Turbuhaler) to pressing a button (Genuair).
Soft Mist Inhaler is the latest delivery system. It uses mechanical energy to deliver medication as soft mist over a short time. It enables the best delivery of medication to the lungs and does not require forceful inhalation. It needs to be primed for first use as well as subsequent use if it hasn’t been used for a long time. Currently, there is only one type of device known as the Respimat that is a soft mist inhaler.
With so many inhalations available, some argue that the first step in the management of COPD is to select the most appropriate device for the patient. Once the device is selected, then one can determine what medication or combination of medications should be prescribed based on the the disease severity and symptomatology.
Below is a summary table of all the inhalation devices and medications currently available in Canada:
Although we have many more sophisticated inhalation devices for the management of COPD 20 years later, I still think it is better to prevent the disease with smoking cessation. But for those individuals with well established COPD, I hope these new gadgets will make a difference in their lives.