Prescription Medications for the Treatment of Obesity - Pamphlet

Pamphlet by: National Institute of Diabetes & Digestive & Kidney Diseases, Feb 1, 2001

* Medications That Promote Weight Loss

* Single Drug Treatment

* Combined Drug Treatment

* Potential Benefits of Medication Treatment

* Potential Risks and Concerns When Considering Medication

* Commonly Asked Questions About Weight-Loss Medications

* What to Discuss with Your Doctor Before Choosing Weight-Loss Medication

* Appropriate Treatment Goals for Using Prescription Weight-Loss Medications

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 was 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 As a result of these reports, the manufacturer has voluntarily withdrawn two medications, fenfluramine (Pondimin) and dexfenfluramine (Redux) from the market.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 studies lasting more than 2 years evaluating the safety or effectiveness of weight-loss medications. In particular, the safety and effectiveness of combining more than one weight-loss medication or combining weight-loss medications with other medications for the purpose of weight loss is unknown. Weight-loss 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

Most available weight-loss medications are "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.

In 1999, the drag orlistat was approved by the Food and Drug Administration (FDA) as an obesity treatment. Orlistat works by reducing the body's ability to absorb dietary fat by about one third.

Most currently available weight-loss medications are approved by the U.S. Food and Drug Administration (FDA) for short-term use, meaning a few weeks or months. Sibutramine and orlistat are the only weight-loss medications approved for longer-term use in significantly obese patients, although the safety and effectiveness have not been established for use beyond 1 year. (See table 1 for the generic and trade names of prescription weight-loss 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 weight-loss medication at a time (combined drug treatment) is an example of an off-label use. Using weight-loss medications other than sibutramine or orlistat for more than a short period of time (i.e., more than "a few weeks") is also considered off-label use.

Table 1
Prescription Weight-Loss Medications

Generic Name        Trade Name(s)

Dexfenfluramine     Redux (withdrawn)
Diethylpropion      Tenuate, Tenuate dospan
Fenfluramine        Pondimin (withdrawn)
Mazindol            Sanorex, Mazanor
Orlistat            Xenical
Phendimetrazine     Bontril, Plegine, Prelu-2, X-Trozine
Phentermine         Adipex-P, Fastin, Ionamin, Oby-trim
Sibutramine         Meridia

Single Drug Treatment

Several weight-loss 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-drag obesity treatments. People respond differently to weight-loss 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. Both orlistat and sibutramine have been studied for as long as 2 years in some patients.