Obesity Drugs: Are They Worth It?

Orlistat

Orlistat (Xenical) reduces intestinal fat absorption by inhibiting pancreatic lipase. Originally available only by prescription, it was approved by the FDA for over-the-counter sale in February 2007. Orlistat may cause frequent, oily bowel movements (steatorrhea), but if fat in the diet is reduced, symptoms often improve.

Sibutramine

Sibutramine (Reductil or Meridia) is an anorectic or appetite suppressant, reducing the desire to eat. Both drugs have side effects. Sibutramine may increase blood pressure and may cause dry mouth, constipation, headache, and insomnia.

Rimonabant

Rimonabant (Acomplia) is a recently developed anti-obesity medication. It acts on the brain thus decreasing appetite. It may also act by increasing energy expenditure. These drugs not only cause weight loss, but prevent or reverse the metabolic effects of obesity, such as insulin resistance and hyperlipidemia.

Weight loss with rimonabant however has not been shown to be greater than other available weight loss medication. Due to safety concerns, primarily psychiatric in nature, the drug has not received approval in the United States or Canada, either as an anti-obesity treatment or as a smoking-cessation drug.

Sanofi-Aventis has received approval to market rimonabant as a prescription anti-obesity drug in the European Union, subject to some restrictions.

Metformin

In people with Diabetes mellitus type 2, the drug metformin (Glucophage) can reduce weight.[5]

Exenatide

Exenatide (Byetta) is a long-acting analogue of the hormone GLP-1, which the intestines secrete in response to the presence of food. Among other effects, GLP-1 delays gastric emptying and promotes a feeling of satiety. Some obese people are deficient in GLP-1, and dieting reduces GLP-1 further. Byetta is currently available as a treatment for Diabetes mellitus type 2. Some, but not all, patients find that they lose substantial weight when taking Byetta.

Drawbacks of Byetta include that it must be injected twice daily, and that it causes severe nausea in some patients, especially when therapy is initiated. Byetta is recommended only for patients with Type 2 Diabetes. A somewhat similar drug, Symlin, is currently available for treating diabetes and is in testing for treating obesity in non-diabetics.

Pramlintide

Pramlintide (Symlin) is a synthetic analogue of the hormone Amylin, which in normal people is secreted by the pancreas in response to eating. Among other effects, Amylin delays gastric emptying and promotes a feeling of satiety. Many diabetics are deficient in Amylin. Currently, Symlin is only approved to be used along with insulin by Type 1 and Type 2 diabetics. However, Symlin is currently being tested in non-diabetics as a treatment for obesity. A drawback is that Symlin must be injected at mealtimes.

Other drugs

Other weight loss drugs have also been associated with medical complications, such as fatal pulmonary hypertension and heart valve damage due to Redux and Fen-phen, and hemorrhagic stroke due to phenylpropanolamine. Many of these substances are related to amphetamine.

Nonprescription products or programs(not researched) for weight loss are heavily promoted by mail and print advertising and on the internet. The US Food and Drug Administration recommends caution with use of these products, since many of the claims of safety and effectiveness are unsubstantiated. Individuals with anorexia nervosa and some athletes try to control body weight with laxatives, diet pills or diuretic drugs, although these generally have no impact on body fat. Products that work as a laxative can cause the blood's potassium level to drop, which may cause heart and/or muscle problems. Pyruvate is a popular product that may result in a small amount of weight loss. However, pyruvate, which is found in red apples, cheese, and red wine, has not been thoroughly studied and its weight loss potential has not been scientifically established.

Side effects

Some anti-obesity drugs have severe and often life-threatening side effects. (for example, Fen-phen.) These side effects are often associated with their mechanism of action. In general, stimulants carry a risk of high blood pressure, faster heart rate, palpitations, closed-angle glaucoma, drug addiction, restlessness, agitation, and insomnia.

Another drug, orlistat, blocks absorption of dietary fats, and as a result may cause oily spotting bowel movements (steatorrhea), oily stools, stomach pain, and flatulence. A similar medication, designed for patients with Type 2 diabetes, is Acarbose which partially blocks absorption of carbohydrates in the small intestine, and produces similar side effects including stomach pain, and flatulence.

Limitations of current knowledge

The limitation of drugs for obesity is that we do not fully understand the neural basis of appetite and how to modulate it. Appetite is clearly a very important instinct to promote survival. Arguably any drug that would abolish appetite may carry a high mortality risk and may be unsuitable for clinical use.

Because the human body uses various chemicals and hormones to protect its stores of fat (a reaction probably useful to our ancestors when food was scarce in the past,) there has not yet been found a 'silver bullet', or a way to completely circumvent this natural habit of protecting excess food stores. Because of this, anti-obesity drugs are not a practical long-term solution for people who are overweight.

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