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Obesity Drug Treatment to Reduce Weight
Single and Combined Medications that Promote Weight Loss in Obese Patients
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Use of Pharmacological Drugs to Reduce Clinical Obesity

Weight Loss Drug Treatment of Obesity

Questions About Obesity Medications
Appetite Suppressants - Anti-Obesity Drugs - Prescription Obesity Drugs
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Doctors are increasingly turning to weight loss drugs to deal with overweight and obesity. Due to lack of research into the long-term success rates of such obesity drug treatment, it's effectiveness for weight control remains inconclusive.

Note: Drug Treatment for Obesity is a Health Rather than Cosmetic Concern

Weight-loss medications may be appropriate for carefully selected patients who are at significant medical risk because of their obesity. They are not recommended for use by people who are only mildly overweight unless they have health problems that are made worse by their weight. These medications should not be used only to improve appearance.

Obesity Drug Treatment
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 drug 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.

Obesity Drug Treatment - Short Term Use Only

  • Most 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.
  • 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. FDA-approved Prescription Weight Loss Drugs

Weight Loss Drug Brand Name
Dexfenfluramine Redux (withdrawn)
Diethylpropion 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

Obesity Drug Treatment - 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-drug 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.
  • 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.

Note: Amphetamines and closely related compounds are not recommended for use in the treatment of obesity due to their potential for abuse and dependence.

Obesity Drug Treatment - Combined Drug Treatment

Combined drug treatment using fenfluramine and phentermine ("fen/phen") is no longer available due to the withdrawal of fenfluramine from the market. Little information is available about the safety or effectiveness of other drug combinations for weight loss, including fluoxetine/phentermine, phendimetrazine/phentermine, Xenical/sibutramine, herbal combinations, or others. Until more information on their safety or effectiveness is available, using combinations of medications for weight loss is not recommended except as part of a research study.

Obesity Drug Treatment
Potential Benefits of Weight Loss Medication Treatment

Over the short term, weight loss in obese individuals may reduce a number of health risks.

Studies looking at the effects of weight-loss medication treatment on obesity-related health risks have found that some agents lower blood pressure, blood cholesterol, and triglycerides (fats) and decrease insulin resistance (the body's inability to use blood sugar) over the short term.

However, long-term studies are needed to determine if weight loss from weight-loss medications can improve health.

Obesity Drug Treatment
Potential Risks and Concerns When Considering Medication

When considering long-term weight-loss medication treatment for obesity, you should consider the following areas of concern and potential risks.

Potential for Abuse or Dependence
Currently, all prescription medications to treat obesity except orlistat are controlled substances, meaning doctors need to follow certain restrictions when prescribing many weight-loss medications. Although abuse and dependence are not common with non-amphetamine appetite-suppressant medications, doctors should be cautious when they prescribe these medications for patients with a history of alcohol or other drug abuse.

Development of Tolerance
Most studies of weight-loss medications show that a patient's weight tends to level off after 4 to 6 months while still on medication. While some patients and physicians may be concerned that this shows tolerance to the medications, the leveling off may mean that the medication has reached its limit of effectiveness. Based on the currently available studies, it is not clear if weight gain with continuing treatment is due to drug tolerance.

Obesity Drug Treatment
Reluctance to View Obesity as a Chronic Disease

Obesity often is viewed as the result of a lack of willpower, weakness, or a lifestyle "choice" - the choice to overeat and underexercise.

  • The belief that persons choose to be obese adds to the hesitation of health professionals and patients to accept the use of long-term appetite-suppressant medication treatment to manage obesity.
  • Obesity, however, is more appropriately considered a chronic disease than a lifestyle choice. Other chronic diseases, such as diabetes and high blood pressure, are managed by long-term drug treatment, even though these diseases also improve with changes in lifestyle, such as diet and exercise.
  • Although this issue may concern physicians and patients, social views on obesity should not prevent patients from seeking medical treatment to prevent health risks that can cause serious illness and death.
  • Appetite-suppressant medications are not "magic bullets" or a one-shot fix. They cannot take the place of improving one's diet and becoming more physically active.
  • The major role of medications appears to be to help a person stay on a diet and exercise plan to lose weight and keep it off.

Obesity Drug Treatment - Side Effects

Because weight-loss medications are used to treat a condition that affects millions of people, many of whom are basically healthy, their potential for side effects is of great concern.

  • Most side effects of these medications are mild and usually improve with continued treatment. Rarely, serious and even fatal outcomes have been reported.
  • Two approved appetite-suppressant medications that affect serotonin release and reuptake have been withdrawn from the market (fenfluramine, dexfenfluramine).
  • Medications that affect catecholamine levels (such as phentermine, diethylpropion, and mazindol) may cause symptoms of sleeplessness, nervousness, and euphoria (feeling of well-being).
  • Sibutramine acts on both the serotonin and catecholamine systems, but unlike fenfluramine and dexfenfluramine, sibutramine does not cause release of serotonin from cells. The primary known side effects of concern with sibutramine are elevations in blood pressure and pulse, which are usually small but may be significant in some patients. People with poorly controlled high blood pressure, heart disease, irregular heart beat, or history of stroke should not take sibutramine, and all patients taking the medication should have their blood pressure monitored on a regular basis.
  • Some side effects with orlistat include oily spotting, gas with discharge, urgent need to go to the bathroom, oily or fatty stools, an oily discharge, increased number of bowel movements, and inability to control bowel movements. These side effects are generally mild and temporary, but may be worsened by eating foods that are high in fat. Also, because orlistat reduces the absorption of some vitamins, patients should take a multivitamin at least 2 hours before or after taking orlistat.
  • Primary pulmonary hypertension (PPH) is a rare but potentially fatal disorder that affects the blood vessels in the lungs and results in death within 4 years in 45 percent of its victims. It should be noted that the vast majority of cases of PPH have occurred in patients who were taking fenfluramine or dexfenfluramine, either alone or in combination. There have been only a few case reports of PPH in patients taking phentermine alone, although the possibility that phentermine alone may be associated with PPH cannot be ruled out. No cases of PPH have been reported with sibutramine, but because of the low incidence of this disease in the underlying population, it is not known whether or not sibutramine may cause this disease.

Obesity Drug Treatment - Appropriate Treatment Goals

If you and your doctor believe that the use of weight-loss medications may help you, discussing the goals of treatment is important.

  • Improving your health and reducing your risk for disease should be the primary goals.
  • For most severely obese people, achieving an "ideal body weight" is both unrealistic and unnecessary to improve their health and reduce their risk for disease. Most patients should not expect to reach an ideal body weight using the currently available medications.
  • Even a modest weight loss of 5 to 10 percent of your starting body weight can improve your health and reduce your risk factors for disease.
  • Use of weight-loss medications for cosmetic purposes is not appropriate.
  • Weight-loss medications should be used with a program of behavioral treatment and nutritional counseling designed to help you make long-term changes in your diet and physical activity.
  • You should see your physician regularly so that he or she can monitor how you are responding to the medication, not only in terms of weight loss, but how it affects your overall health.
  • Again, if you experience any serious symptoms, such as chest pains or shortness of breath, contact your doctor immediately.

Obesity Drug Treatment - Long-Term Use and Safety

Long-term use of prescription weight-loss medications may be helpful for carefully selected individuals, but little information is available on the safety and effectiveness of these medications when used for more than 2 years. By evaluating your risk of experiencing obesity-related health problems, you and your physician can make an informed choice as to whether medication can be a useful part of your weight-management program.

Sources: Weight Control Information Network (WIN). National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)


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