Should You Use A Spacer With Symbicort

Your Question. If you read the package insert for Symbicort, it says not to use with a spacer. What should we make of this? It seems to me that common sense would point to using a spacer with it, considering it is an inhaler. What do you think?

My Answer. That is a very good question. There are actually two ways of looking at this.

One, that Symbicort is still a relatively new product, and it has yet to have been studied with a spacer. For this reason, their lawyers may require them to make this note on the package insert.

Two, the dose of medicine is adjusted based on estimated distribution to the airways. It is well known
that only 9% of medicine inhaled by metered dose inhalers makes it to the lower airways where it is needed. To compensate for this low distribution percentage, the dose of Symbicort was adjusted to obtain maximal results. Wanting to limit side effects, the makers of Symbicort (AstraZeneca) and their lawyers decided to put the disclaimer on the package insert that a spacer should not be used.

So, you might be thinking, so why then should you not use a spacer? The general thinking is that a spacer would improve coordination, reduce side effects, and improve distribution. A spacer will surely reduce impaction of medicine particles in your upper airway, thereby reducing side effects. However, these medicine particles cause systemic side effects only after they are swallowed. These medicine particles are broken down (metabolized) by the liver, where almost all of them are excreted in urine. Only a tiny fraction gets into your bloodstream and has a chance to cause systemic side effects. This is called first pass metabolism, meaning that your digestive tract and liver significantly breaks down the medicine before it reaches your circulation.

Now, let's look at the medicine that makes it to your airways. Studies show that 10-40% of this medicine will come into contact with blood vessels in your lungs. If you use a spacer and increase lung distribution, that means that you are getting more medicine to airways. You'd think this is a good thing, resulting in better asthma control (although modern studies can even debate that). However, while true, it also increases the amount of medicine that comes into contact with pulmonary blood vessels. These medicine particles do not participate in first pass metabolism. Instead, a majority, if not all, of these particles directly enter your circulatory system, where they might participate in systemic side effects.

So, while a spacer might improve coordination and reduce side effects, not using a spacer may reduce side effects even more so than using a spacer. This is important, because this is how pharmaceuticals like AstraZeneca prevent side effects from corticosteroids and long-acting beta adrenergic medicines.

Bottom line, the dose of Symbicort is adjusted to account for a lung distribution of only 9%. If it were assumed that 100% of patients used a spacer with Symbicort, then the dose of the medicine would be adjusted downward to compensate for the improved lung distribution. This would be necessary to prevent side effects. So, I know this was a complicated explanation, but might explain why the package insert for Symbicort recommends that no spacer be used.

So, what should you do? Personally, where I work we distribute spacers with all inhaler products. I think this is the way it will be done until the medical profession adjusts to this new wisdom. For legal and ethical purposes, I think following your hospitals policy is the best policy. However, when you are using your own inhaler product, whether you use a spacer is up to you.

References.

“A Guide for Aerosolized Delivery Devices for Respiratory Therapists,” 3rd edition, https://www.aarc.org/education/online-courses/aerosol-devices/, accessed 8/4/17

Irwin, et al., “Side Effects With Inhaled Corticosteroids,” Chest, July, 2006, http://journal.chestnet.org/article/S0012-3692(15)32956-1/pdf, accessed 8/3/17

“Spacers with inhalers: Do they make a difference,” American Academy of Allergy, Asthma, and Immunology, 2017, Jan. 18, https://www.aaaai.org/global/latest-research-summaries/New-Research-from-JACI-In-Practice/spacer-inhaler, accessed 8/5/17

Saag, Kenneth G., et al., “Major Side Effects of Glucocorticosteroids,” 2017, https://www.uptodate.com/contents/major-side-effects-of-inhaled-glucocorticoids, accessed 8/3/17

Barnes, Peter, J., "Inhaled Corticosteroids," Pharmaceuticals (Basal), 2010, March 3, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4033967/, accessed 8/1/17

Romme, “Fracture Prevention in COPD: A clinical 5-step approach,” Respiratory Research, 2014, https://respiratory-research.biomedcentral.com/articles/10.1186/s12931-015-0192-8, accessed 6/20/17