U.S. drug reviewers recommended that regulators further study the effects in children of a group of medicines known as atypical antipsychotics, a report released on Friday said.

Food and Drug Administration staff said a recent study of health insurance claims found children treated with the drugs were much more likely to experience an adverse metabolic effect than adults, and the likelihood was directly correlated with age.

Metabolic effects can include abnormal weight gain, diabetes and increases in cholesterol and blood pressure.

Although observational studies have limitations ... this provocative hypothesis should nonetheless be subject to some further evaluation by the agency, staff in the FDA's division of pharmacovigilance wrote in an October 14 memo.

Earlier on Friday, AstraZeneca announced the FDA had approved use of the company's atypical antipsychotic Seroquel in schizophrenia patients ages 13 to 17 and bipolar disorder patients ages 10 to 17.

The atypical antipsychotics are cleared to treat those diseases as well as depression and other mental illnesses. The medicines also are increasingly prescribed to children for unapproved uses such as attention deficit hyperactivity disorder, or ADHD.

The FDA took a closer look at the drugs' use in children after a panel of outside advisers in November 2008 asked for more long-term data on the drugs' effects in youths. The agency will discuss its most recent findings at a public meeting of that panel on Tuesday.

The report released on Friday said an FDA analysis showed increased reporting of metabolic problems with Eli Lilly & Co's Zyprexa and AstraZeneca's Seroquel. Those findings by themselves may not reflect true agent-specific differences in risk, the agency staff added.

Reporting rates jumped for Zyprexa in 2006 and for Seroquel in 2007, the FDA staff said. Those spikes may be partly explained by cases submitted by law firms involved in suits against the companies, the reviewers said.

Lilly spokesman Jamaison Schuler said Lilly has acknowledged greater risks for younger patients treated with Zyprexa.

The drug is not approved for children, but applications for adolescents are pending. If approved, clinicians should take into consideration the increased potential for weight gain and (elevated blood fats) in adolescents compared to adults, and the potential for long-term risks, which in many cases may lead them to consider prescribing other drugs first, Schuler said.

The FDA staff memo, written before Friday's approval of Seroquel for adolescents, recommended the Seroquel data undergo further review as was previously done for Zyprexa.

In a statement announcing Seroquel's approval for youths, AstraZeneca said the drug's warnings were updated to include information about weight gain and other issues seen in the studies of adolescents.

The FDA review also included Bristol-Myers Squibb Co and Otsuka Pharmaceutical Co's Abilify, Johnson & Johnson's Risperdal and Pfizer Inc's Geodon.

Officials at those manufacturers did not immediately respond to requests for comment.

Review