An experimental diet drug seems to help some obese people shed kilograms, and keep them off for two years, researchers report.
The drug, which will be called Qnexa if it reaches the market, is a combination of the appetite-suppressant phentermine and the anti-seizure drug topiramate.
So far, it's had a bumpy road to approval. Last year, the US Food and Drug Administration (FDA) rejected Qnexa, citing safety concerns – including elevated heart rate in some users and the potential for birth defects if pregnant women used the drug.
But last month, the FDA accepted a new application from Qnexa maker Vivus Inc., which is now seeking approval for the drug to be marketed with a warning that it shouldn't be used by women of childbearing age.
Drug works better than placebos
The new study, reported in the American Journal of Clinical Nutrition, is an extension of an earlier clinical trial. That one found that Qnexa, added to lifestyle changes, helped obese adults lose more weight over one year, versus placebo pills.
The current study suggests that the benefit lasts for two years, according to researchers led by Dr W. Timothy Garvey of the University of Alabama at Birmingham.
By the end of two years, the 449 men and women randomly assigned to take Qnexa had lost about 10% of their starting weight, on average.
That compared with a 2% decline among 227 people given a placebo.
Drug availability still in the air
Qnexa users also showed a decline in obesity-related health problems. On average, their blood sugar and insulin levels dipped, and they were less likely than placebo users to develop diabetes.
Almost 4% of the placebo group developed diabetes per year. By comparison, just under 2% of people on a lower Qnexa dose developed diabetes each year, as did 1% of those on a higher dose.
Whether the diet drug will actually become available is still up in the air.
Qnexa and two other weight-loss drugs – Arena Pharmaceuticals' lorcaserin and Orexigen Therapeutics' Contrave – were all rejected by the FDA in the past year over potential safety concerns.
Effective weight loss drugs a struggle
All three companies, though, are still working on addressing the FDA's concerns to try to win approval.
Drug makers have struggled for years to develop weight-loss drugs that are both effective and safe.
Back in 1997, the infamous diet drug fen-phen was pulled from the market after reports of fatal heart-valve problems in some users. Another diet pill, Meridia, was pulled from the US market last year after being linked to heart problems.
Drug has some side effects
In this latest Qnexa trial, the most common side effects were upper respiratory infections, constipation, dry mouth and tingling sensations. Over two years, 3% of placebo users and about 4.5% of Qnexa users dropped out of the trial because of side effects.
For now, the drug options are few for obese people who fail to lose weight through diet changes and exercise alone.
The only drug approved for long-term use is orlistat (Xenical), which is also available as a lower-dose, over-the-counter version called Alli. But Xenical has its issues as well, including side effects of gas, uncontrolled bowel movements, and cases of serious liver problems.
(Reuters Health, December 2011)