The US Food and Drug Administration has ordered Glenmark Generics of Mahwah, New Jersey, and Konec Inc. of Tucson, Arizona, to stop marketing unapproved nitroglycerin tablets. The tablets are placed under the tongue to relieve chest pain or to stop a heart attack and are marketed in 0.3 mg, 0.4 mg, and 0.6 mg dosages.

The FDA does not anticipate a supply problem for these products. Pfizer Inc. markets FDA-approved sublingual nitroglycerin tablets in the same strengths and is able to supply the market with approved products. The FDA also will work with patient organizations and health care professionals to ensure that they are aware that an approved product is available.

The agency's warning letters require Glenmark and Konec to remove the unapproved tablets as part of the FDA's Unapproved Drugs Initiative1. The initiative was announced in 2006 to address marketed drugs that had not received FDA approval.

The unapproved nitroglycerin tablets have not been proven safe and effective, and the FDA has not reviewed the quality and labelling of these products. The unapproved products may differ from approved nitroglycerin products in some respects, such as formulation and labelling. The FDA has seen significant quality and efficacy problems with some unapproved nitroglycerin products.

"Doctors and patients should know that not all drugs on the market are backed by an FDA approval," said Deborah M. Autor, director of the Office of Compliance at the FDA's Center for Drug Evaluation and Research (CDER). "This lack of approval undermines the FDA's efforts to ensure that safe and effective drug products are available to the American public."

Consumers using the unapproved products should continue taking their medication and consult a health care professional for guidance on alternative treatment options.

"Consumers are entitled to know that their drugs meet FDA standards, and it is a priority for the agency to remove from the market unapproved products that expose consumers to potentially unsafe, ineffective, or poor quality drugs," said CDER Director Janet Woodcock, M.D. "The FDA remains committed to ensuring that prescription drugs obtain the necessary FDA approval, and we urge companies to actively pursue such approvals."

Glenmark and Konec have 15 days to respond to the FDA with a plan for removing their products from the market. They have 90 days from the date of the warning letters to stop manufacturing new products and 180 days to stop further shipment of existing products.