Availability of MDI, DPI, and Nebulizers in the United States
“In the United States there are no DPI formulations of short-acting 2 agonists. Most are available in either nebulizer or MDI, and only one formulation (pirbuterol) is available in a breath-actuated device. Conversely none of the long-acting bronchodilators are available in the United States in MDI form.”(2) Because there are a certain amount of choices for drug/device combinations, this may limit a clinician’s this will limit the available regimen choices and may increase the likelihood that patients will be put on more than one type of device for their asthma or COPD.(2) Also, “since the inhalation techniques are different for the various devices, this may lead to increased confusion in the patient who uses more than one device type.” (2)
Advantages and Disadvantages of MDIs, DPIs, and Nebulizers
For nebulizers, one important advantage is that there is no special technique to use them if tidal breathing is sufficient. “Nebulizers can be used at any age, and for any disease severity or acuity. In some cases it is possible to mix more than one medication in a nebulizer and deliver them simultaneously, though this lengthens the administration time. One of the benefits of nebulizers with diseases other than asthma and COPD is the ability to use very high drug doses… Finally, nebulizers contain no propellants that can damage the atmosphere and they require very little teaching in clinic.”(2) The disadvantages of nebulizers include that they are more time consuming to use compared to MDIs and DPIs. Also, nebulizers require more careful cleaning and are less portable compared to MDIs and DPIs.
For MDIs the advantages are that they are small and easily portable. Also, they are very cheap. The disadvantages are that “MDIs do not have incorporated dose counters, so it is difficult to tell how much drug remains.”(2) “The technique and coordination required for efficient MDI use make it the most difficult of all the aerosol devices. If there is a delay between actuation and inhalation, or if the patient inhales too rapidly, the delivery to the lower airways will be affected. A whole industry of spacer and holding-chamber devices has popped up over the last 2 decades to help improve coordination and reduce the oropharyngeal deposition of the high-velocity sprays from MDIs”(2) “Since MDIs are the most difficult device to use, teaching MDI use may be a problem in a busy clinical practice. Also, even if patients understand perfectly how to use the device properly, they may contrive to use the devices incorrectly, thus not obtaining the maximum benefit.”(2)
“DPIs are the newest type of aerosol delivery device and come in many forms. There are single-dose devices that use drug contained in a capsule, multi-dose devices with bulk drug and a dosing chamber, and multi-dose devices with individual doses inside. In general, DPIs are easier to use than MDIs because they are breath-actuated. The energy from the patient’s inhalation disaggregates the powder into smaller particles. DPIs do not contain propellants, and DPIs are very portable and quick to use. Spacers are not necessary with DPIs. The multi-dose DPIs incorporate dose counters and are easier to teach than MDIs.”(2) The disadvantages for using DPIs include a higher respiratory rate needed. Also, children less than 5 years of age should not use the device since they likely will not have adequate technique. (2)
Efficacy of using A Metered Dose Inhaler Vs. Nebulizer for Asthma Exacerbations
“Several studies have demonstrated that for mild to moderate asthma exacerbations, administering a beta-agonist via an MDI [metered dose inhaler] with a spacer is as effective as using a nebulizer.”(1) In 2006, physicians administered nebulizer therapy at more than 3.6 million emergency department visits.(1) Physicians continue to administer nebulizers instead of MDIs despite the fact that MDIs are just as effective and have other benefits compared to nebulizers. These benefits include that MDIs “cost less and don’t require maintenance or a power source.”(1)
A systematic review looked at certain outcomes in EDs, hospitals, and outpatient settings that included children and adults. The primary outcomes were hospital admission rates and duration of hospital stay. Secondary outcomes included time spent in the ED, change in pulse rate, and incidence of tremor.(1) The systematic review concluded that there were no difference in hospital admission rates when administering a beta-agonist medication with an MDI through a spacer compared to a nebulizer. Also, the systematic review concluded that “duration in the ED was approximately half an hour shorter for children using spacers”(1) …and “there was no difference in time spent in the ED observed in adults.”(1) Finally, the systematic review concluded that for the secondary outcome, in children, spacers are associated with lower rates of side effects, including tremor and elevated pulse rate.
Another randomized control study compared MDIs to breath actuated nebulizers. The purpose of the study was to determine “if metered dose inhalers are as effective as breath actuated nebulizers for the treatment of mild to moderate asthma exacerbations in pediatric patients presenting to the emergency department. Half of the participating patients received albuterol via the metered dose inhaler whereas the other half received albuterol via the breath actuated nebulizer.”(3) The study concluded that MDIs are non-inferior to breath actuated nebulizers for the treatment of mild to moderate asthma.(3)
Finally, the last study obtained was a meta-analysis, which looked at various studies “To compare the effects of nebulisers versus pressurised metered dose inhalers (pMDI) plus spacer or dry powder inhalers (DPI) in bronchodilator therapy for exacerbations of COPD.”(4) The study concluded that “there was no difference between nebulizers versus pMDI plus spacer regarding the primary outcomes of FEV1 at one hour and safety. For the secondary outcome,”’change in FEV1 closest to one hour after dosing during an exacerbation of COPD, [there was] found a greater improvement in FEV1 when treating with nebulisers than with pMDI plus spacers.”(4)
(1) Kirley K, Nguyen L. PURLs: Think twice about nebulizers for asthma attacks. J Fam Pract. 2014;63(6):321-46. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4140108/
(2) Geller DE. Comparing clinical features of the nebulizer, metered dose inhaler, and dry powder inhaler. Respir Care. October 2005, 50 (10) 1313-1322; Available from: http://rc.rcjournal.com/content/50/10/1313
(3) A Randomized Trial Comparing Metered Dose Inhalers and Breath Actuated Nebulizers. ClinicalTrials.gov. Available from: https://clinicaltrials.gov/ct2/show/study/NCT02777125?cond=A+Randomized+Trial+Comparing+Metered+Dose+Inhalers+and+Breath+Actuated+Nebulizers&rank=1
(4) Douma WR, Geffen WH, Kerstjens H, Slebos DJ. Bronchodilators delivered by nebuliser versus pMDI with spacer or DPI for exacerbation of COPD. Cochrane Library. August 29, 2016. Available from: https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD011826.pub2/full#CD011826-sec1-0003