New Drug May Boost Weight Loss Efforts
Tesofensine Helps Obese People Lose Weight in Early Studies
Oct. 22, 2008 -- An experimental diet drug may prove to be twice as
effective as currently available weight loss medications if results from an
early study are confirmed.
Researchers did not compare the drug tesofensine head-to-head with currently
approved weight loss medications. But researcher Arne Astrup, MD, of the
University of Copenhagen tells WebMD that the weight loss in the study was
roughly double that reported in trials of these drugs.
Danish biopharmaceutical company Neurosearch A/S, which hopes to market
tesofensine as a weight loss drug, paid for the study.
"Normally the drugs now on the market give you at best a weight loss of
5 kilograms (11 pounds) with diet and exercise," Astrup says. "In this
study we doubled that weight loss."
Tesofensine Targets Appetite Centers
Astrup says the drug works on three different appetite regulatory centers of
the brain -- the neurotransmitters noradrenaline, dopamine, and serotonin.
The phase II study, reported today in The Lancet, included 203 obese
patients whose average weight was about 220 pounds.
All the participants were placed on a calorie-restricted diet and all were
asked to increase their physical activity to between 30 minutes to an hour a
Participants were treated with either a placebo, 0.25 milligrams of
tesofensine, 0.5 milligrams of the drug, or 1 milligram of the drug daily.
In all, 161 of the participants completed the six-month study, with average
weight loss ranging from a low of around 5 pounds in the placebo group to 28
pounds among patients taking the highest dose of the tesofensine.
But patients on the highest dose of the experimental drug also showed
significant increases in blood pressure.
Because of this, patients who participate in a planned phase III study of
the drug will be treated with the 0.5 milligram dose, which rivaled the higher
dose in terms of weight loss in the phase II trial but elicited only a slight
increase in pressure over placebo.
A spokeswoman for Neurosearch A/S tells WebMD that the phase III trials are
planned for both the U.S. and Europe. Assuming the trials are positive, the
company hopes to have the drug on the market within four years.
Checking the Drug's Safety
Thomas Wadden, PhD, who directs the University of Pennsylvania School of
Medicine Center for Weight and Eating Disorders, tells WebMD that the phase III
study should help answer important questions about the safety of the
experimental weight loss drug.
"The phase II results are very promising, but larger studies are needed
to confirm the findings and tell us more about the safety profile," he
Wadden says the blood pressure finding is particularly troubling, as was the
finding that study participants treated with tesofensine reported more anger,
hostility, and confusion than participants in the placebo arm of the study.
"We need to do more extensive assessment of the psychiatric effect of
medications like this one that operate on the central nervous system," he