Oct. 22, 2009 -- The injectable diabetes drug liraglutide appears to help obese people who do not have diabetes shed extra pounds, but larger studies are needed to prove its safety and effectiveness for weight loss, researchers say.
Liraglutide has been approved for the treatment of type 2 diabetes in Europe, but it is not yet approved for use in the United States.
In earlier studies, diabetes patients who received once-daily injections of the drug lost weight and showed improvements in blood sugar.
In the newly published study, overweight people without diabetes who received daily injections of liraglutide lost more weight than patients treated with the oral weight loss drug orlistat, sold as Xenical and Alli in the U.S.
The mechanism by which the drugs affect weight is not completely understood, but they are believed to suppress appetite and delay the movement of food from the stomach to the small intestine. The thinking is that this helps people feel full longer after eating.
Liraglutide and Weight Loss
The 20-week weight loss study included 564 obese people with body mass indexes (BMI) of between 30 and 40, treated at 19 sites throughout Europe.
Participants received either daily injections of one of four doses of liraglutide, injections of an inactive placebo, or the weight loss drug orlistat taken orally three times a day.
All the study participants followed calorie-restricted diets, which contained about 500 fewer calories a day than they needed to maintain their weight. They also increased their physical activity.
By the end of the study, the liraglutide-treated patients had lost significantly more weight than either the placebo-treated patients or those who took the oral weight loss drug.
Orlistat-treated patients lost an average of 9 pounds during the 20-week study, compared to a weight loss of 10.5 pounds in patients on the lowest dose of liraglutide (1.2 milligrams a day).
Patients treated with the highest dose of the liraglutide (3 milligrams daily) lost the most weight, averaging nearly 16 pounds. These patients also had the most nausea and vomiting, with 3.5% of participants withdrawing from the study as a result of these side effects.
Placebo-treated patients lost the least amount of weight -- about 6 pounds.
The study was paid for by liraglutide manufacturer Novo Nordisk, which has also provided independent financial support to several study authors.
Weight Loss ‘Shots’?
Researchers say longer studies will be needed to determine the drug’s long-term risk-benefit profile as a weight loss treatment.
Novo Nordisk Chief Science Officer Mads Krogsgaard Thomsen tells WebMD the company will decide whether to go ahead with larger studies once the FDA decides whether or not to approve liraglutide for use as a diabetes treatment in the U.S.
That decision is expected by the end of the year.
“The study published today in Lancet is encouraging, but it is important to stress that this is only phase II data,” Thomsen says.
Weight loss researcher George A. Bray, MD, tells WebMD that it remains to be seen if people will embrace a weight loss drug that they have to inject, even if it proves to be more effective than approved oral treatments.
Patients who take Byetta inject the drug twice a day; liraglutide is given once a day.
“My guess is that there will be much longer acting versions of both these drugs in the future that will require much less frequent injections,” Bray says. “But it still isn’t clear if people who aren’t used to injections will take shots to lose weight.”
Novo Nordisk is now testing a drug similar to liraglutide that is injected once a week instead of once a day.
Bray would also like to see studies to determine if combining Byetta or liraglutide with approved weight loss drugs leads to bigger weight loss than has been reported with any of the drugs alone.
“It is clear that (Byetta and liraglutide) promote weight loss in diabetes patients,” he says. “But their safety and usefulness for weight loss in people without diabetes remains to be proven.”