The weight-loss drug Meridia may be a safe, effective treatment for severely overweight children as young as 12, researchers reported Monday.

In a study of nearly 500 obese 12- to 16-year-olds, investigators found that children who took Meridia, and also underwent behavioral counseling, lost an average of 14 pounds over a year. In contrast, those who received counseling alone continued to gain weight.

The findings are published in the Annals of Internal Medicine.

Meridia, known generically as sibutramine, is approved in the U.S. as a weight-loss aid for people ages 16 or older. The new findings suggest the drug is "relatively safe and effective" for younger teens as well, said lead study author Dr. Robert I. Berkowitz of Children's Hospital of Philadelphia.

However, he told Reuters Health, more research is needed to see how effective the drug is in the long term -- including whether young users keep the weight off and whether they develop fewer obesity-related health problems, like type 2 diabetes and heart disease.

Berkowitz also stressed that medication is an option only for teens with severe weight problems. "This is not for children who need to lose 20 pounds," he said.

Meridia, which acts as an appetite suppressant, has been the subject of some controversy in the past. Consumer advocacy group Public Citizen has repeatedly called on U.S. regulators to pull the drug, citing reported deaths from cardiovascular problems among users.

In the current study, rapid heart rate was the only side effect seen significantly more often in children using Meridia compared with those given a placebo -- 12.5 percent, versus 6.2 percent.

Berkowitz said that, as in adults, it would be important to monitor heart rate and blood pressure in children taking Meridia.

The study included 498 obese adolescents at 33 U.S. weight-loss clinics who were randomly assigned to take either Meridia or placebo pills daily. All children received lifestyle counseling to help them change their eating and exercise habits and manage stress.

Meridia maker Abbott Laboratories supplied the medication and the study funding.

After one year, children on Meridia had lost an average of 14 pounds, while those on placebo had gained a few pounds, on average. Meridia users also showed greater improvements in their levels of "good" HDL cholesterol and blood fats called triglycerides.

"That's a clinically significant weight loss," Berkowitz said.

However, one of the unanswered questions, according to the researcher, is whether many children would regain the weight if they went off the drug, as has been seen with adults.

SOURCE: Annals of Internal Medicine, July 18, 2006.