WASHINGTON - The Food and Drug Aministration told manufacturers of unapproved extended-release cough and cold drugs that contain an expectorant called guaifenesin they have until Nov. 25 to stop shipping medicines.

The FDA said Friday that roughly 20 companies make hundreds of timed-release medicines containing guaifenesin that have never undergone an agency review. They are expected to stop making the drugs even earlier, by Aug. 27, health officials said. The drugs are sold both by prescription and over the counter, as both single-ingredient and combination products.

Friday's action does not affect products containing guaifenesin in immediate-release form, the FDA said. The agency said it knew of no safety issues with guaifenesin, which stimulates removal of mucus from the lungs and has been used in medicines for decades.

Only one company, Adams Respiratory Therapeutics Inc., currently has FDA approval to sell extended-release guaifenesin in single-ingredient versions such as Mucinex and Humibid.

In 2002, the FDA sent warning letters to 18 manufacturers and 48 repackers and distributors of single-ingredient guaifenesin extended-release products, telling them they required approval to sell their products. It warned them again in 2003.

A year later, the FDA then approved combination versions of Mucinex that included either a cough suppressant or decongestant.

The FDA identified Crantex and Guaifenex as among the biggest selling names of unapproved, immediate-release guaifenesin medicines, as of 2006. Crantex's distributor, Breckenridge Pharmaceutical Inc., of Boca Raton, Fla., will comply with the FDA and halt distribution by the November deadline, said Larry Lapila, vice president of business development for the privately held company.

A message left with Ethex Corp., the St. Louis company that distributes Guaifenex, was not immediately returned.

Any company that wants to sell medicines containing guaifenesin in timed-release form must seek FDA approval, the agency said. Approval, however, would be subject to patent rights held by Adams Respiratory Therapeutics, it added.

In March, Adams Respiratory Therapeutics settled a lawsuit against United Research Laboratories and Mutual Pharmaceutical Co., which had sought to sell generic versions of Mucinex and Humibid. Under the settlement, URL/Mutual won't be able to sell versions of the drugs until 2012 - unless another company successfully challenges Adams' patent, which expires in 2020.

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On the Net: http://www.fda.gov/OHRMS/DOCKETS/98fr/07n-0193-n000001.pdf