FDA warns drugmakers on unapproved migraine drugs

WASHINGTON (Reuters) - The U.S. Food and Drug Administration has ordered 20 companies, including Novartis AG's Sandoz unit, to stop marketing a number of unapproved drugs used to fight headaches, the agency said on Thursday.

The FDA sent warning letters to eight manufacturers, which also included Ivax Pharmaceuticals Inc., recently acquired by Teva Pharmaceutical Industries Ltd. Twelve distributors also were warned.

Like other approved products for migraine and other headaches, the drugs contain the active ingredient ergotamine tartrate. But they have been manufactured and distributed without undergoing review by the FDA, the agency said.

"Doctors and patients often do not realize that not all drugs that are available on the market are backed by FDA approval," said FDA's Deborah Autor, who oversees compliance issues. She added that fewer than 2% of prescription medications are unapproved.

"Drugs that skirt the approval process may be unsafe, may not work, and in our experience, often have inadequate labeling," she said in a statement.

The unapproved ergotamine tartrate drugs do not carry necessary cautions against their use in patients also taking the metabolic enzyme inhibitor CYP 3A4 found on labels for similar approved headache drugs, the FDA said.

Such inhibitors can include certain antibiotics, antifungal treatments and protease inhibitors.

The FDA posted the letters, dated February 26, on its Web site at http://www.accessdata.fda.gov/scripts/wlcfm/date.cfm?MONTH=2&YEAR=2007