Guide to Prescription Weight Loss Drugs

Welcome to the guide to prescription weight loss drugs. The purpose of this guide is to provide information on popular prescription weight loss drugs. Information here is from the MEDLINEplus, National Institute of Diabetes and Digestive and Kidney Diseases and US Food and Drug Administration government websites.

For obese people who have difficulty losing weight through diet and exercise alone, there are a number of FDA-approved prescription drugs that may help. "On average, individuals who use weight loss drugs lose about 5 percent to 10 percent of their original weight, though some will lose less and some more," says the FDA's Colman.

All of the prescription weight loss drugs work by suppressing the appetite except for Xenical (orlistat). Approved by the FDA in 1999, Xenical is the first in a new class of anti-obesity drugs known as lipase inhibitors. Lipase is the enzyme that breaks down dietary fat for use by the body. Xenical interferes with lipase function, decreasing dietary fat absorption by 30 percent. Because the undigested fats are not absorbed, fewer calories are available to the body. This may help in controlling weight. The main side effects of Xenical are cramping, diarrhea, flatulence, intestinal discomfort, and leakage of oily stool.

Meridia (sibutramine), approved by the FDA in 1997, increases the levels of certain brain chemicals that help reduce appetite. Because it may increase blood pressure and heart rate, Meridia should not be used by people with uncontrolled high blood pressure, a history of heart disease, congestive heart failure, irregular heartbeat, or stroke. Other common side effects of Meridia include headache, dry mouth, constipation and insomnia.

Other anti-obesity prescription drugs that were approved by the FDA many years ago based on very short-term, limited data include: Bontril (phendimetrazine tartrate), Desoxyn (methamphetamine) and Ionamin and Adipex-P (phentermine). They are "speed"-like drugs that should not be used by people with heart disease, high blood pressure, an overactive thyroid gland, or glaucoma. These drugs are approved only for short-term use, such as a few weeks. They generally don't cause weight loss beyond several weeks, and they have significant potential for physical dependence or addiction.

"There is no magic pill for obesity," says David Orloff, M.D., director of the FDA's Division of Metabolic and Endocrine Drug Products. "The best effect you're going to get is with a concerted long-term regimen of diet and exercise. If you choose to take a drug along with this effort, it may provide additional help."

Until September 1997, two other drugs, fenfluramine (Pondimin and others) and dexfenfluramine (Redux), were available for treating obesity. But at the FDA's request, the manufacturers of these drugs voluntarily withdrew them from the market after newer findings suggested that they were the likely cause of heart valve problems. The FDA recommended that people taking the drugs stop and that they contact their doctor to discuss their treatment. (For the latest information on this topic, visit www.fda.gov/cder/news/feninfo.htm.)

Prescription weight loss drugs are approved only for those with a BMI of 30 and above, or 27 and above if they have other risk factors, such as high blood pressure or diabetes.

People should contact a doctor before using any kind of drug, including a weight loss drug.


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