Should You Take the New FDA-Approved Weight-Loss Pill?

Certain dieters now have a new weapon to fight obesity. Wednesday the FDA approved Belviq (lorcaserin hydrochloride), the first new prescription drug for long-term weight loss in more than a decade. 

The weight-loss pill is approved as an addition to exercise and cutting calories for people who are obese (a BMI of 30 or more) or overweight (a BMI of 27 or more) with at least one weight-related disorder, such as high blood pressure, type 2 diabetes, or high cholesterol.

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How Does Belviq Work?

Belviq targets a brain area that influences appetite, called the serotonin 2C receptor. It’s the same receptor targeted by fenfluramine, the "fen" component of the infamous 1990s diet drug combo fen-phen.

However, Belviq is considered safer because it’s more selective—specifically targeting serotonin receptors linked to hunger, using a different brain pathway than fen-phen did. The new diet pill curbs appetite by boosting feelings of fullness and satiety, so people eat less.

How Effective is Belviq for Weight Loss?

In three randomized clinical trials involving nearly 8,000 overweight and obese adults, those who took Belviq for up to one year, in combination with cutting calories and exercise, dropped an average of 3 to 3.7 percent of their body weight. For a 200-pound person, that would be a loss of 6 to 7.4 pounds.

About 47 percent of patients without diabetes shed at least 5 percent of their starting weight—enough to significantly reduce their risk for diabetes and other health problemscompared to only 23 percent of those treated with a placebo. About 38 percent of diabetic patients treated with Belviq and 16 percent of placebo users lost at least 5 percent of their body weight. Diabetics who took the drug also had beneficial changes in blood sugar control.

NOTE: The FDA advises people who haven’t lost at least 5 percent of their body weight after taking Belviq for 12 weeks to stop the drug, since further treatment is unlikely to help them slim down.

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Past Safety Concerns for Diet Drugs

The approval comes after a long line of safety concerns about prescription diet drugs, such as the notorious two-drug weight-loss combination phen-fen, which was taken off the market in 1997 after the previously cocktail of phentermine and fenfluramine was linked to heart-valve problems in up to one in three users.

With America’s obesity rate nearing 35 percent of the adult population, doctors called upon the FDA to approve more weight-loss treatments. Previously, there was only one FDA-approved drug for long-term weight loss—Xenical, which is rarely prescribed due to unpleasant digestive side effects.

Four years ago Sanofi-Aventis SA halted studies of its highly anticipated weight-loss pill Acomplia, which turned out to have scary psychiatric side effects, including depression and suicidal thoughts.

In 2010, the FDA refused to approve Belviq, due to concern that it might cause similar damage. That year the FDA also shot down two other experimental diet drugs because of serious potential side effects. However, three clinical trials involving more than 8,000 people found no significant difference in the rate of heart-valve problems among those who took Belviq and people given a placebo.

The FDA issued a press release reporting that Belviq “does not appear to activate "a chemical pathway linked to the heart-valve problems seen with fen-phen.” Nor does it appear to have the problems associated with Accutrim, which was pulled from the market in 2000 due to its link to strokes.

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Does Belviq Have Risks?

The FDA's 2010 refusal to approve Belviq also stemmed from a concern that it raised the rate of breast and brain tumors in rats given seven times the dosage recommended for people. New studies by the maker of Belviq found little risk for tumors in people.

The FDA reports that the most common side effects of Belviq in non-diabetic patients are headache, dizziness, fatigue, nausea, dry mouth, and constipation. In diabetic patients side effects include low blood sugar (hypoglycemia), headache, back pain, cough, and fatigue.

The drug can have serious side effects, according to the FDA, which include serotonin syndrome, a potentially deadly (though rare) condition marked by such symptoms as confusion, restlessness, blood pressure changes, nausea, vomiting, and loss of muscle coordination. Risk goes up if you also take other medications that affect serotonin levels, such as certain common drugs for migraine or depression.

What Are the Benefits?

"The approval of this drug, used responsibly in combination with a healthy diet and lifestyle, provides a treatment option for Americans who are obese or are overweight and have at least one weight-related comorbid condition," said FDA's drug center director, Dr. Janet Woodcock, in a statement.

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Who Should Avoid Belviq?

Belviq should only be used by overweight or obese people under a doctor's supervision. Pregnant women should not use the new diet pill. People with heart failure should use it with caution, warns the FDA, due to preliminary evidence that it might have problematic effects.

The agency has ordered the drug’s manufacturer to conduct after-market studies to monitor people who use Belviq for any cardiovascular complications that might emerge with wider use of the new medication.


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