How do over-the-counter (OTC) medicines for asthma work?
Epinephrine acts by relaxing the muscles of the airways, thereby opening up the airways and allowing air to flow in and out of the lungs more easily. Ephedrine also relaxes the muscles of the airways.
What factors should be considered in choosing and using OTC epinephrine or ephedrine?
Despite the development of newer medications, epinephrine and ephedrine remain available as OTC medications. The choice of epinephrine or ephedrine should involve consideration of several factors. Most importantly, the asthma should be mild and less frequent, defined as occurring less than once per week and lasting from a few hours to a few days at most. OTC epinephrine or ephedrine is best used under the guidance of a physician. You should seek medical attention and prepare to switch to a prescription asthma medication if:
- moderate to severe asthma develops,
- frequent or regular doses of epinephrine or ephedrine are needed to relieve symptoms,
- episodes of asthma occur once or more per week, or
- asthmatic episodes develop at night.
OTC epinephrine is available in various concentrations for oral inhalation or as a solution in vaporized form (nebulization). Both forms may or may not contain alcohol or sulfite as preservatives. For example, AsthmaHaler Mist does not contain alcohol. Alcohol and sulfite preservatives may trigger an attack of asthma, and therefore, patients whose asthma is sensitive to these preservatives should read product labels carefully. The nebulized epinephrine solutions may or may not require diluting with a separate saline (salt) solution before use. Several saline solutions are available OTC in various concentrations. Again, careful reading of the label will provide information about combining an epinephrine solution for nebulization with a specific saline solution. Oral epinephrine is unavailable because it is rapidly broken down in the digestive system before it can reach the lungs. Once inhaled, epinephrine should provide rapid relief of symptoms (within five to 10 minutes) and continue working for one to three hours. Good inhaler and nebulizing techniques are critical in the use of epinephrine. If epinephrine is used frequently, tolerance to its effects occurs; that is, repeated inhalations provide progressively less and less benefit. Some of these inhalers use a chlorofluorcarbon (CFC) propellant. These gases have been shown to damage the ozone layer. The FDA is likely to expand the ban on CFC propellants making these agents unavailable in the near future.
OTC ephedrine is available only as an oral medication in combination with guaifenesin as caplets, tablets, or syrup. (Guaifenesin is an expectorant that loosens mucus in the airways and facilitates its removal by coughing.) Caution should be used when first starting these products since they occasionally irritate the airways of some patients and may make the asthma worse. OTC ephedrine should provide relief of symptoms within 15-60 minutes and may continue to be effective for three to five hours. Continued use of ephedrine, like frequent use of epinephrine, leads to tolerance.
Neither epinephrine or ephedrine should be continued if thick mucus or sputum (colored mucus) develops and/or a persistent or chronic cough occurs with the asthma. These may be signs of infection in the lungs and require immediate medical attention. If OTC asthma drugs do not relieve an episode of asthma within 10 (for epinephrine) or 60 minutes (for ephedrine) or the symptoms worsen, medical attention should be sought immediately.
Credit: George Schiffman, MD, FCCP, Medicine.net