SILVER SPRING, Md. — The Food and Drug Administration is alerting users of over-the-counter asthma inhalers containing chlorofluorocarbons (CFCs) to get a prescription for a replacement medication since these products won’t be made or sold by the year’s end.

The FDA said Thursday that epinephrine inhalers, marketed by Armstrong Pharmaceutical Inc. as Primatene Mist, are being phased out because no CFC-laden inhalers can be made or sold after Dec. 31, 2011, to comply with obligations made under the Montreal Protocol on Substances that Deplete the Ozone Layer.

Under the international agreement, the United States and other nations agreed to phase out substances that deplete the ozone layer, including CFCs, after certain dates. Primatene Mist is the only FDA-approved inhaler for the temporary relief of occasional symptoms of mild asthma sold in retail stores without a prescription. The product uses CFCs to propel the medicine out of the inhaler so that consumers can breathe it into their lungs.

"If you rely on an over-the-counter inhaler to relieve your asthma symptoms, it is important that you contact a health care professional to talk about switching to a different medicine to treat your asthma," stated Badrul Chowdhury, M.D., director of the Division of Pulmonary, Allergy and Rheumatology Products in the FDA’s Center for Drug Evaluation and Research.

The FDA said it began public talks about the use of CFCs in epinephrine inhalers in January 2006. The agency finalized the phase-out date for using CFCs in the inhalers and notified the public in November 2008.

Many manufacturers have changed their inhalers to replace CFCs with an environmentally friendly propellant called hydrofluoroalkane (HFA), yet there’s currently no HFA version of epinephrine inhalers, according to the FDA. The agency noted that many other safe and effective inhalers to treat asthma symptoms are available but require a prescription.

Primatene Mist already carries a prominent notice about the phase-out date on its product label, the FDA pointed out. The agency added that it will continue to work with retailers and pharmacies to facilitate a smooth phase-out of the CFC product and that it’s ready to review applications for replacement products.