A new nitroglycerin treatment for chest pain that may signal a heart attack -- currently a leading form of angina therapy in Europe -- has been cleared for marketing by the U.S. Food and Drug Administration, according to Wyeth-Ayerst Laboratories in Philadelphia.
The nitrate compound -- a pill that needs to be taken twice daily -- is expected to be on the market by mid-March, Audrey Ashby, a spokesman for Wyeth-Ayerst, clinical developers of the drug in this country, said yesterday.
It will be available in pharmacies under the trademark Ismo, Ashby said.
In five different clinical trials at medical centers throughout the country, Ismo, or iosorbide mononitrate, has demonstrated that it avoids the gradual loss of efficacy seen in older nitrates in both oral and patch formulations, Ashby said.
Ismo, unlike other nitrate tablets, is nearly 100 percent bioavailable, which means that almost all of it is absorbed by the body.
Another attractive feature that differentiates Ismo from other nitrates is that dosage adjustments are not required for elderly patients or in patients with various degrees of kidney, blood or cardiac dysfunctions, Ashby said.
The side effects of Ismo -- the first new nitrate drug therapy for angina in 30 years -- are similar to those seen in other nitrates, according to Wyeth-Ayerst. The most common are headache, dizziness and nausea.
In recent years, two other classes of drugs, beta blockers and calcium channel blockers, have provided effective alternatives to the traditional nitroglycerin treatments for many of the 3 million Americans who have chest pains from atherosclerosis, or clogged arteries.
Nitrates relieve chest pain by dilating the blood vessels, particularly the veins, which results in reduction of blood being returned to the heart from the veins. This shrinks the size of the heart, which reduces tension in the heart's wall. The heart then works less to pump blood.
In Europe, Ismo has been developed by Boehringer Mannheim GmbH. Boehringer Mannheim's U.S. pharmaceutical affiliate, Boehringer Mannheim Pharmaceuticals Corp., will participate in the promotion of the product in the United States.
Wyeth-Ayerst Laboratories, a division of American Home Products Corp., is a major research-oriented pharmaceutical company with leading products in female health care, cardiovascular and metabolic disease therapies, anti-inflammatory agents, vaccines and infant nutritionals.