WASHINGTON (AP) -- The first of a trio of new weight loss drugs gets officially unveiled this week, carrying hope of success where others failed -- safely delivering significant weight loss.

With U.S. obesity rates nearing 35 percent of the adult population, expectations are high for the first new prescription drug therapies to emerge in more than a decade.

But none of the three medicines represents a breakthrough in research. Two of the drugs submitted for approval simply combine existing drugs, but have worrying side effects. The third, a new medication, is safer but less effective.

The FDA is expected to post its review of Vivus (VEE'-vuhs) Inc.'s pill Qnexa (kyoo-NEHX'-uh) on Monday and will hold a public meeting Thursday to review the data.

Other drugs are set for review in October and December.

(Copyright ©2010 by The Associated Press. All Rights Reserved.)