FDA Removing Over-the-counter Asthma Drug From Shelves for Environment

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Users of Primatene Mist, the only over-the-counter treatment for acute symptoms of asthma, will need to find an alternative as of December 31, 2011. The U.S. Food and Drug Administration (FDA) recently announced that the medication will no longer be available because it uses chlorofluorocarbons (CFCs) as a propellant agent [1], and CFCs have long been known to deplete Earth’s ozone layer.

Primatene Mist contains epinephrine, also called adrenaline, which stimulates the sympathetic branch of the body’s autonomic nervous system.

The adrenal glands, which are situated on top of each kidney, produce epinephrine and release it in response to a real or perceived threat. Epinephrine can also be administered as a medication, either through injection or inhalation, and has the same effects as the natively-produced hormone. Effects of epinephrine include an increase in heart rate and respiration rate, altered distribution of blood flow, and relaxation of the muscles in the small airways. This last effect is the one relevant to asthmatics, who experience constriction of the small airways in response to environmental or emotional triggers, resulting in decreased air flow. There are many different prescription therapies for asthma, including short-acting bronchodilators (so-called “rescue” inhalers), long-acting bronchodilators, steroids and leukotriene inhibitors. Of all the options available for treating asthma by prescription, albuterol — a short-acting bronchodilator — is the closest to epinephrine from a pharmacological standpoint; it is fast-acting and helps to relax the muscles of the small airways.

The removal of Primatene Mist from drugstore shelves has nothing to do with the active ingredient in the medication; instead, the FDA is responding to the Montreal Protocol, a universally ratified treaty designed to protect the Earth’s ozone layer, the thin layer of O₃ gas in the stratosphere that reacts with, and thereby helps to shield Earth’s inhabitants from, ultraviolet (UV) radiation from the sun. Overexposure to UV radiation damages biomolecules, including DNA, and leads to a variety of negative outcomes including skin cancer.

CFCs, while completely non-toxic, react with ozone molecules in the upper atmosphere, resulting in the catalytic destruction of ozone (meaning that each molecule of CFC can react with and destroy hundreds of thousands of ozone molecules).

Among the stipulations of the Montreal Protocol is a mandated phase-out of CFCs, and their replacement with alternative, non-ozone-depleting substances. Many different asthma inhalers depend upon propellants to help aerosolize and deliver medication. Albuterol was among the prescription asthma treatment drugs affected by an earlier FDA mandate that pharmaceutical companies had to replace CFCs with alternative propellants in prescription inhalers by December 31, 2008. Primatene Mist, because it is an over-the-counter medication, was subject to a slightly later phase-out date. The replacement propellants used in prescription inhalers are hydrofluoroalkanes (HFAs), which don’t have the ozone-depleting potential that CFCs do. Unfortunately, however, HFAs are significantly more expensive to produce than CFCs, which has made HFA-propelled asthma inhalers more expensive than their CFC predecessors. Compared to CFC-propelled inhalers, HFA-propelled inhalers release medication at lower temperature, and less forcefully [2]. However, the inhalers are just as effective at delivering the appropriate dose. While it would be possible to replace the propellant in Primatene mist with an HFA, so far, the company has announced no plans to do so.

The FDA advises asthmatics who rely upon Primatene Mist as a rescue inhaler to see a physician for prescription asthma medication, but recognizes that this may represent a financial hardship for those without health insurance, owing to the greater cost of prescription inhalers as compared to Primatene Mist. Patients without health insurance or prescription coverage may be eligible for assistance through federally funded health care centers.

References

1. Primatene Mist With Chlorofluorocarbons No Longer Available After Dec. 31, 2011. U.S. Food and Drug Administration consumer update. Accessed 2011 Sep 29.
2. HFA Inhalers — Physician Information. Asthma and Allergy Foundation of America. Accessed 2011 Sep 29.