Fen-Phen Overview - FindLaw
Created by FindLaw's team of legal writers and editors| Last reviewed January 28, 2013
What is "Fen-Phen"?
Fen-phen refers to the use in combination of the drugs fenfluramine and phentermine. Phentermine has also been used in combination with dexfenfluramine ("dexfen-phen"). Fenfluramine ("fen") and phentermine ("phen") are prescription medications that were approved by the FDA for many years as appetite suppressants for the short-term (a few weeks) management of obesity. Phentermine was approved in 1959 and fenfluramine in 1973. Dexfenfluramine (Redux) was approved in 1996 for use as an appetite suppressant in the management of obesity.
In the 1990's, some physicians began prescribing fenfluramine or dexfenfluramine in combination with phentermine, often for extended periods of time, for use in weight loss programs. Use of drugs in ways other than described in the FDA-approved label is called "off-label use." In the case of fen-phen and dexfen-phen, no studies were presented to the FDA to demonstrate either the effectiveness or safety of the drugs taken in combination, so use of the drugs in combination never received FDA approval.
Fenfluramine and Dexfenfluramine: Withdrawal from Market
In September 1997, the FDA asked the manufacturers to voluntarily withdraw dexfenfluramine and fenfluramine from the market. Dexfenfluramine was manufactured for Interneuron Pharmaceuticals and marketed under the name "Redux" by Wyeth-Ayerst Laboratories, a subsidiary of American Home Products Corp. of Madison, N.J., which also manufactured and marketed fenfluramine under the brand name "Pondimin." Both companies agreed to voluntarily withdraw their drugs. The FDA did not request the withdrawal of phentermine, the third widely used medication for obesity.
The FDA's withdrawal request came after echocardiogram testing of fen-phen patients suggested that fenfluramine and dexfenfluramine were the likely cause of heart valve problems (more on heart valve problems and risks to fenfluramine and dexfenfluramine users follows below).
On September 15, 1997, FDA recommended that patients using either of these products stop taking them, and advised patients to contact their doctors to discuss their treatment.
Studies Reveal Heart Valve Problems
In July 1997, researchers at the Mayo Clinic and Mayo Foundation reported 24 cases of rare valvular disease in women who took the "fen-phen" combination therapy. Later, FDA received 66 additional reports of heart valve disease associated mainly with "fen-phen." There were also reports of cases seen in patients taking only fenfluramine or dexfenfluramine.
The heart contains four major valves that regulate the flow of blood through the heart and to the lungs and general circulation. Disease may cause excessive tightness (stenosis) or leakiness (regurgitation) of the valves. In the case of valve disease associated with fenfluramine and dexfenfluramine, leakiness is the problem. Valvular damage may ultimately produce severe heart and/or lung disease.
Heart Risks for Fenfluramine and Dexfenfluramine Users
Patients who have taken fenfluramine and dexfenfluramine may have changes in their heart valves that cause leakiness and backflow of blood. If this is severe, the heart has to work harder. This may cause problems in heart function.
The patient may have no symptoms. The physician may hear a new heart murmur (abnormal sound as the blood flows over a valve), or the changes may be detected with a painless, non-invasive special heart test called an echocardiogram. An echocardiogram is usually performed by a cardiologist. If the disease is severe, the patient may experience such symptoms as shortness of breath, excessive tiredness, chest pain, fainting, and swelling of the legs (edema).
Since fenfluramine and dexfenfluramine were pulled from the market, hundreds of former fen-phen patients have filed lawsuits against the drugs' manufacturers, including a nationwide class action suit that was settled and received judicial approval in January 2002. If you or a loved one have suffered illness or injury as a result of Fen-phen drug use, your rights may be impacted by the nationwide class action or by other legal proceedings related to Fen-phen. But you may still be entitled to file a lawsuit for any harm caused by Fen-phen drug use, especially if your health problems or risks were discovered only recently. The best way to ensure that your legal rights are protected is to contact an attorney, who will consider your case and explain your options.