RE: Dry powder inhalers are environmentally preferable to metered-dose inhalers
References
Kimberly Wintemute, Fiona Miller. Dry powder inhalers are environmentally preferable to metered-dose inhalers. CMAJ 2020;192:E846-E846.
Ismaila AS, Sayani AP, Marin M, Su Z. Clinical, economic, and humanistic burden of asthma in Canada: a systematic review. BMC Pulmonary Medicine. 2013 Dec 1;13(1):70.
National Institute for Health and Care Excellence (NICE). Patient decision aid: inhalers for asthma. Available: https://www.nice.org.uk/guidance/ng80/resources/inhalers-for-asthma-patient-decision-aid-pdf-6727144573 (accessed Sept. 21, 2020).
von Hertzen L, Beutler B, Bienenstock J, et al. Helsinki alert of biodiversity and health. Ann Med. 2015; 47(3):218-225. doi:10.3109/07853890.2015.1010226
The Paris Agreement. November 4, 2016. https://cop23.unfccc.int/process-and-meetings/the-paris-agreement/the-paris-agreement (accessed Sept. 21, 2020).
We add our voice to support of Wintemute & Miller’s (2020) call for action to promote use of dry powder inhalers (DPIs) for asthma management. While drug coverage and development of Canadian-specific patient information is essential, it does not preclude immediate action.
Asthma affects over 3 million Canadians (8.5% of the population over 12 years of age) and that number is growing (Ismaila et al. 2013) – driven partly by adverse environmental conditions, and partly by the loss of biodiversity on the planet from climate change and human actions (von Hertzen et al. 2015). Physicians need to act now. The impact that inhalers have on the environment matters to our patients, and our children. Physicians can start to discuss health in terms of “co-benefits”: a health decision that is good for the patient and good for the environment. If a patient is able to “breathe in through their mouth quickly and deeply for 2-3 seconds” then DPIs are a viable option for them – and they do not have to time their inhalation! (NICE 2020)
Switching from an MDI to a propellant-free DPI could save the equivalent emissions of 54 km of driving per patient per month based on once daily dosing (*see assumptions below). Switching 144 patients from MDI to DPI would save the equivalent of driving the entirety of the Trans-Canada Highway in a month.
Disposal of inhalers is another matter. Although inhalers are made of recyclable plastic and metal, they are considered hazardous waste as they have come into contact with human biology. Most empty inhalers surrendered to community pharmacies are incinerated. Given that “empty” MDIs contain a small amount of residual propellant, this means that we are not only releasing incinerated puffer container plastics into the atmosphere, but we’re also converting the residual propellant into equivalent atmospheric greenhouse gases as well.
As physicians, each of us can play our part starting now. Working in partnership with patients we can use our prescribing power to better the environment and start honoring commitments described in The Paris Agreement (2016). If the pen is mightier than the sword, let us wield our prescription pads as a far-reaching ordnance against the climate crisis right now.
*Calculation assumptions:
- 1 dose pMDI = 2 puffs, and 1 dose DPI = 1 puff
- pMDI standard 16 mL/puff (large) using HFA – 134a norflurane as propellant
- DPI emissions from embodied CO2eq of delivery mechanism (2014 Report of the UNEP Medical Technical Options Committee)
- Monthly use: 2 doses/day/person for 30 days
- Product monographs