One down, two to go. The FDA just rejected approval of a new weight loss drug called Qnexa, and is scheduled to consider two more later this year. Next up to bat is lorcaserin: a new study published in The New England Journal of Medicine suggests that the drug may offer some nice benefits to those trying to lose weight – and with fewer side-effects than drugs of the past.

The study, funded by lorcaserin’s maker, Arena, followed 3,182 overweight or obese patients for two years to see how they fared. For the first year, half the patients took the drug twice a day, and the other half served as controls and took a placebo. Participants were given counseling on healthy diet and exercise.

The authors say that there was no increase in problems with heart valve function in the people taking lorcaserin, which was the reason for the now infamous weight-loss drug, Fen-Phen, being pulled from the shelf.

After the first year, 47% of the people in the lorcaserin group had lost at least 5% of their body weight, while only 20% of the control group had lost this amount. For the second year of the study, half the people in the lorcaserin group continued taking the drug, and the other half switched to placebo. For the people who kept on taking it, about 68% maintained their weight loss over this year, vs. 50% of the people who had switched to placebo.

The authors say that there was no increase in problems with heart valve function in the people taking lorcaserin, which was the reason for the now infamous weight-loss drug, Fen-Phen, being pulled from the shelf. The most common side effects of the drug were dizziness, nausea, headache, and upper respiratory infections, but these tended to get better over time, the authors report. On the positive side, there were other, healthy changes like lowered blood pressure, blood fats, insulin resistance, and levels of inflammation in the lorcaserin group.

The authors conclude that, “[l]orcaserin was associated with significant weight loss, as compared with placebo, in obese and overweight adults when administered in conjunction with a nutritional and physical exercise program.” They add, however, that “[a]s with any drug, the benefit must be balanced against the risk.” Although the study does provide some promising results for the drug, more research will be needed to look at the long term benefits and risks. And the FDA still has to make a ruling before the drug will be available to the public.

The study, led by Steven R. Smith at the Translational Research Institute for Metabolism and Diabetes in Winter Park, FL, was published in the July 15, 2010 online edition of The New England Journal of Medicine.