Dr. Brown is an assistant professor of pharmacy practice at Palm Beach Atlantic University, Lloyd L. Gregory School of Pharmacy, Palm Beach, Florida.
Billy is a regular customer in your pharmacy who comes in with a new prescription for albuterol. As he hands you the prescription, he states, "Don't give me that ?new inhaler' that you did last time. That thing doesn't work! I want the one that I used to get." As you glance at his profile, you notice that Proventil HFA was dispensed approximately 1 month ago, and this was the first time that he has received 1 of the newly formulated MDIs. How would you respond?
Metered dose inhalers (MDIs) were first introduced into the market in the 1950s by Riker Laboratories when the daughter of the company president asked her father why her medication for asthma could not be given in spray formulation like hairspray. This idea eventually led to the development of MDIs, among the most commonly used devices in the world for respiratory diseases such as asthma and chronic obstructive pulmonary disease.1,2
Though these devices are widely used, they are heavily dependent on patient technique and the ability to properly actuate the device. Most of the medication delivered via the MDI does not reach its intended destination. In fact, 10% to 25% of the medication actually makes it to the lungs, with the majority of it depositing in the oropharynx, and some of the medication being retained in the mouthpiece of the device.1,2
In 1974, it was first theorized that the propellant contained in all MDIs, chlorofluorocarbon (CFC), was linked to ozone layer depletion. The argument of how MDIs damage the ozone layer has been raised as patients are inhaling the product, not spraying it into the atmosphere. Emission of CFCs into the air occurs as patients exhale as part of MDI delivery.
Until 1995, all MDIs contained CFCs.1 In an effort to minimize damage to the ozone layer, the Montreal Protocol called for the phasing out of CFC-containing products; in response, pharmaceutical companies established the International Pharmaceutical Aerosol Consortium to research and develop formulations that would serve as suitable alternatives to CFC-containing MDIs.1,4
One potential solution was to allow dry powder inhalers (DPIs) to replace MDIs. Though frequently used today in the delivery of inhaled glucocorticoids and long-acting beta2 agonists, DPIs can be expensive to manufacture, are adversely affected by humidity, and require fast inhalation, which potentially could be problematic in patients with severely diminished lung function.2 Thus, attention turned to the hydrofluoroalkanes (HFAs), particularly HFA-134a (also known as tetrafluoroethane) and HFA-227 (also known as heptafluoropropane), as a new propellant for MDIs. HFAs have not been linked to depletion of the ozone layer and are nonflammable. It should be noted, however, that these agents still contribute to the greenhouse effect, but to a lesser extent compared with CFCs.1
The FDA has required that all MDIs containing CFCs cannot be marketed after December 31, 2008.5 Pharmacies have begun the transition to the new HFA-containing MDIs, and many patients are being switched over to the new products. Additionally, the FDA has proposed a new rule to remove the "essential use" designation from epinephrine-containing MDIs currently available over the counter. Under this rule, epinephrine products containing CFCs would be phased out by 2010. If a non-CFC product containing epinephrine is not available by this time, a prescription for an alternative would be required.6
With the development of HFA-containing MDIs, manufacturers had to ensure they were equivalent to CFC-containing MDIs. This prompted reevaluation of MDI performance, particularly assessment of both inter- and intra-patient dosing inconsistencies, the "cold" effect often described with inhalation involving Freon, force of the spray, and effect of humidity. A wider mouthpiece, smaller actuator orifice, spray temperature above freezing, and reduced jetting velocity (force of spray) all have contributed to a difference in feel, sound, and shape of the new HFA-containing MDIs.2 As such, many patients like Billy may state that they do not feel the newer devices are effective. Patient education can play a large role in helping patients understand the differences in the newer devices.
Many patients may question why they must be switched to the newer HFA-containing MDIs. It is important to stress that the change has resulted from environmental damage associated with the older CFC-containing MDIs, not damage to the physical health of the patient. Stressing the importance of proper device technique—along with demonstration—may alleviate patient concern for those who cannot feel or taste the dose contained in HFA MDIs.
It is estimated that approximately two thirds of patient users and health care providers involved in MDI technique training do not perform the process correctly.2 The Table contains the appropriate steps involved in MDI usage. In addition, cost is a common concern among patients with the phase out of the old inhalers. The new medications generally are reported to be more expensive than the older generic products that were available; however, their use should continue to be encouraged as a quick relief medication, especially in emergencies. Use of the agents potentially can be minimized with appropriate controller medications for respiratory conditions.
With the phase out of the CFC-containing MDIs, pharmacists are in a pivotal position to educate patients on the importance of appropriate device technique and how the newer HFA-containing devices differ from older ones.
Steps Involved in the Appropriate Use of MDIs
MDI = metered dose inhaler.
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