The U.S. Food and Drug Administration on Thursday approved esomeprazole magnesium, also known as Nexium for short treatment of gastroesophageal reflux disease (GERD) in children ages 1 to 11.

The FDA cleared two formulations, a delayed-release capsule, and esomeprazole magnesium liquid, in 10-mg or 20-mg doses, half the dosage for patients aged 12 to 17.

“This approval provides important information for appropriate dosing for children ages 1-11 years with GERD. Children prescribed this drug should be monitored by their physicians for any adverse drug reactions,” Julie Beitz, MD, director of the FDA’s Office for Drug Evaluation III in the Center for Drug Evaluation and Research said quoted by WebMD.

Nexium, manufactured by AstraZeneca of Wilmington, Del., was the world’s second-best selling drug in 2006, according to health care research firm IMS Health. The drug is known as a proton pump inhibitor, which reduces the amount of acid produced in the stomach and helps heal damage to the esophagus caused by excess acid.

The approval is based on data extrapolated from previous studies done in adults, as well as studies done in children, the FDA said. In one study, 109 GERD patients aged 1-11 were treated with Nexium once daily for up to eight weeks to evaluate Nexium’s safety and tolerability. Most of the patients showed healing of their esophageal erosions after eight weeks of treatment.

The most common adverse reactions in children treated with esomeprazole magnesium were headache, diarrhea, abdominal pain, nausea, gas, constipation, dry mouth, and sleepiness. Beitz said that children treated with the drug “should be monitored by their physicians for any adverse drug reactions.

The safety and efficacy of esomeprazole magnesium has not been established in children less than one year of age, the FDA said.