New anti-obesity drug promises double weight loss

October 23, 2008

A new diet drug, tesofensine, produces twice the weight loss of currently available obesity drugs, Danish researchers report.

According to Dr. Arne Astrup, the lead researcher at the University of Copenghagen, "Tesofensine produces a weight loss of approximately 10 percent more than placebo and diet in obese patients." Other drugs produce only about 5 percent weight loss, Astrup noted.

This drug could replace the need for gastric bypass surgery in some obese patients. "There is an enormous gap between the existing weight-loss compounds and gastric surgery," Astrup said. "Tesofensine could close that gap. If you combine the drug with an effective diet, you could probably reach the 20 percent weight loss seen in gastric surgery."

"Tesofensine could compete with stomach bypass surgery for those who are below the threshold for surgery or for patients who do not wish [to have] gastric surgery," Astrup said. "There are also patients who cannot tolerate the operation."

For the study, Astrup's team conducted a phase II trial in which they randomly assigned 203 obese patients to receive three different daily doses of tesofensine or placebo. The participants were also put on lower calorie diets.

161 people finished the trial. Those taking tesofensine lost more weight than those receiving placebo. Those receiving the lowest dose of tesofensine (0.25 milligrams) lost 14.7 pounds, while those taking 0.5 milligrams lost 25 pounds, and those taking the highest dose (1 milligram) lost 28 pounds. That's a sharp contrast to the weight loss for those taking a placebo- less than 5 pounds.

The pounds lost by those taking tesofensine were double the weight loss seen with drugs already on the market, such as Meridia and Acomplia (rimonabant).

The report was published in the Oct. 23 online issue of The Lancet, a British medical journal.

People taking the highest dose of tesofensine experienced a rise in blood pressure. Other side effects of the drug included dry mouth, nausea, constipation, hard stools, diarrhea and insomnia.

Astrup believes that the 0.5 milligram dose is the best, because it produced weight loss with the fewest side effects.

Tesofensine works by inhibiting the neurotransmitters noradrenalin, dopamine and serotonin in the brain. In turn, this suppresses hunger, leading to an energy deficit which burns excess body fat. The drug's effect was first noticed in trials involving Alzheimer's and Parkinson's patients.

Once starting the drug, people would need to keep taking it to maintain the benefit, Astrup said. "There is no treatment that is working beyond its taking. This is true for all anti-diabetic medication, hypertension medication and everything, including anti-obesity drugs," he said. "It's a long-term treatment, and, in some cases, a permanent treatment to keep body weight down."

Larger clinical trials of tesofensine are expected to begin next year, Astrup said.

Neurosearch, the maker of tesofensine, is seeking approval for the drug in the United States and Europe. Astrup is a paid consultant for Neurosearch and also owns stock in the company.

This trial did find that tesofensine increased heart rate and blood pressure slightly, and reduced lean body mass along with fat mass.

Dr. David L. Katz, director of the Prevention Research Center at Yale University School of Medicine, says the real test for any drug is sustainable weight control over a long term.

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