Prescription Medications for the Treatment of Obesity - Pamphlet

Pamphlet by: National Institute of Diabetes & Digestive & Kidney Diseases, March 16, 1998

Obesity is a chronic disease that affects many people and often requires long-term treatment to promote and sustain weight loss. As in other chronic conditions, such as diabetes or high blood pressure, long-term use of prescription medications may be appropriate for some individuals. While most side effects of prescription medications for obesity are mild, serious complications have been reported. Valvular heart disease has recently been reported to occur in association with the use of certain appetite suppressant medications. As a result of these reports, the manufacturer has voluntarily withdrawn two medications, fenfluramine (Pondimin) and dexfenfluramine (Redux) from the market. There are few long-term studies evaluating the safety or effectiveness of other currently approved appetite suppressant medications. In particular, the safety and effectiveness of combining more than one appetite suppressant medication or combining appetite suppressant medications with other medications for the purpose of weight loss is unknown. Appetite suppressant medications should be used only by patients who are at increased medical risk because of their obesity and should not be used for "cosmetic" weight loss.

Medications That Promote Weight Loss

The medications most often used in the management of obesity are commonly known as "appetite suppressant" medications. Appetite commonly known as "appetite suppressant" medications. Appetite suppressant medications promote weight loss by decreasing appetite or increasing the feeling of being full. These medications decrease appetite by increasing serotonin or catecholamine--two brain chemicals that affect mood and appetite.

Most currently available appetite suppressant medications are approved by the U.S. Food and Drug Administration (FDA) for short-term use, meaning a few weeks or months. Sibutramine is the only appetite suppresant medication approved for longer-term use in significantly obese patients, although the safety and effectiveness have not been established for use beyond one year. (See table 1 for the generic and trade names of prescription appetite suppressant medications.) While the FDA regulates how a medication can be advertised or promoted by the manufacturer, these regulations do not restrict a doctor's ability to prescribe the medication for different conditions, in different doses, or for different lengths of time. The practice of prescribing medication for periods of time or for conditions not approved is known as "off-label" use. While such use often occurs in the treatment of many conditions, you should feel comfortable about asking your doctor if he or she is using a medication or combination of medications in a manner that is not approved by the FDA. The use of more than one appetite suppressant medication at a time (combined drug treatment) is an example of an off-label use. Using currently approved appetite suppressant medication for more than a short period of time (i.e., more than "a few weeks" is also considered off-label use.

Table 1

Prescription Appetite Suppressant Medications

Generic Name              Trade Name(s)
Dexfenfluramine           Redux (Withdrawn)
Diethylpropion            Tenuate, Tenuate dospan
Fenfluramine              Pondimin (Withdrawn)
Mazindol                  Sanorex, Mazanor
Phendimetrazine           Bontril, Plegine, Prelu-2, X-Trozine
Phentermine               Adipex-P, Fastin, Ionamin, Oby-trim
Sibutramine               Meridia

Single Drug Treatment

Several appetite suppressant medications are available to treat obesity. In general, these medications are modestly effective, leading to an average weight loss of 5 to 22 pounds above that expected with non-drug obesity treatments. People respond differently to appetite suppressant medications, and some people experience more weight loss than others. Some obese patients using medication lose more than 10 percent of their starting body weight--an amount of weight loss that may reduce risk factors for obesity-related diseases, such as high blood pressure or diabetes. Maximum weight loss usually occurs within 6 months of starting medication treatment. Weight then tends to level off or increase during the remainder of treatment. Studies suggest that if a patient does not lose at least 4 pounds over 4 weeks on a particular medication, then that medication is unlikely to help the patient achieve significant weight loss. Few studies have looked at how safe or effective these medications are when taken for more than 1 year.

Some antidepressant medications have been studied as appetite suppressant medications. While these medications are FDA approved for the treatment of depression, their use in weight loss is an "off-label" use. Studies of these medications generally have found that patients lost modest amounts of weight for up to 6 months. However, most studies have found that patients who lost weight while taking antidepressant medications tended to regain weight while they were still on the drug treatment.