A Closer Look at the Long-term Use of Pharmacotherapy in the Management of Obesity


The National Task Force on Prevention and Treatment of Obesity has evaluated available research and concludes that appetite suppressant medications, when combined with a healthy diet and increased physical activity, may help some obese individuals lose weight and maintain weight loss for at least 1 year. However, because few studies have evaluated these medications for more than 1 year, the Task Force report suggests that more research is needed on the safety and effectiveness of these medications when used for longer periods of time. These observations are reported in "Long-term Pharmacotherapy in the Management of Obesity," a paper published in the December 18, 1996, issue of the Journal of the American Medical Association.

Currently, most appetite suppressant medications are approved by the U.S. Food and Drug Administration (FDA) for the short-term treatment of obesity (2 to 3 months), with the exception of dexfenfluramine which can be prescribed for up to 12 months. However, many physicians are prescribing these medications to patients for longer periods of time than are approved by the FDA. See table 1 for a list of FDA approved appetite suppressant medications.

To examine the rationale for long-term use of these medications in the management of obesity, the Task Force developed a comprehensive paper on pharmacotherapy. The paper reviews data currently available on the safety and efficacy of appetite suppressant medications and gives patients and practitioners guidance concerning the risks and benefits of using these drugs.

The rationale for using appetite suppressant medications to manage obesity is twofold: 1) the realization that obesity is a chronic disease that affects one in three U.S. adults, and 2) obesity responds poorly to currently available non-surgical treatments. Recognition of the need for long-term (perhaps lifelong) treatment has led many to embrace the concept of long-term medical therapy, as is used in other chronic diseases.

The Task Force conducted a review of available research and found that patients on either single-drug or combination-drug therapy generally lost from 5 to 22 pounds more than patients receiving placebo or nondrug therapies, and most of the weight loss occurred during the first 6 months of treatment. Patients taking the medications longer than 6 months either maintained their weight or experienced partial weight regain. When the weight-loss medications were discontinued, patients regained weight. The review also found that no single drug or combination of drugs has been shown to have superior efficacy in promoting or sustaining weight loss.

The paper provides guidance to practitioners and patients regarding the appropriate use of appetite suppressant medications for managing obesity. "When considering long-term drug treatment for obesity, it is important that physicians and patients are fully informed about the potential risks and benefits and the need for more long-term studies," says Jay Hoofnagle, M.D., Task Force chairman and director of the Division of Digestive Diseases and Nutrition for the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

Most studies examining the potential benefits of drug treatment indicate a possible reduction in obesity-related health risks including lowered blood pressure, blood cholesterol and triglycerides, and decreased insulin resistance over the short term. However, studies are needed to determine if long-term weight loss from appetite suppressant medications can reduce morbidity and mortality.

Most adverse effects of long-term drug treatment are mild and improve with continued treatment. Minor side effects of drugs that affect serotonin levels (such as fenfluramine and dexfenfluramine) include dry mouth, sleep disturbance, sleepiness, frequent urination, and diarrhea. Drugs that affect catecholamine levels (such as phentermine) may cause symptoms of sleeplessness, nervousness, and euphoria.

Although uncommon, serious and even fatal effects have also been reported. Primary pulmonary hypertension (PPH), a rare but serious disorder that affects the blood vessels in the lungs and heart, has been linked in a large case-control study to the use of appetite suppressant medications. The risk for developing PPH is higher in patients who use the medications for more than 3 months but is still very small, estimated at 22-44 cases per million patients per year. Some animal studies have suggested that appetite suppressant medications can lead to central nervous system damage. However, signs of damage to the central nervous system have not been reported in humans, and more studies on the effects of long-term treatment on the central nervous system are needed.

The Task Force concludes that, because obesity is a chronic disorder requiring long-term, perhaps lifelong, treatment, appetite suppressant medications are not recommended for short-term use. "The use of appetite suppressant medications on a long-term basis is consistent with our understanding of obesity as a chronic disease that requires long-term treatment," says Dr. Yanovski. "However, both patients and physicians should be aware that there is little information available on how safe or effective these medications are when used for more than 1 year."

The Task Force recommends that appetite suppressant medications be used only as part of a comprehensive weight management program that includes behavioral approaches to change diet and physical activity. In addition, they recommend that these medications be used only by patients who are at increased medical risk because of their obesity and not for "cosmetic" weight loss. Until more data are available, the Task Force does not recommend pharmacotherapy for routine use in obese individuals, although it may be helpful in carefully selected obese patients.