While the FDA for the first time sanctioned an atypical antipsychotic for use in teens, don’t expect a tidal wave of new prescribing.

The agency gave Johnson and Johnson unit Janssen’s Risperdal (risperidone) its blessing for two psychiatric conditions: treating schizophrenia in adolescents ages 13-17 and for the short-term treatment of bipolar mania associated with manic or mixed episodes of bipolar I disorder in children and adolescents ages 10-17.

Until now, there has been no FDA-approved drug for the treatment of schizophrenia for pediatric use. Lithium has been the only approved drug for treating bipolar disorder in those 12 and up.
But physicians have long prescribed drugs like Risperdal in adolescents off label, a child psychiatrist told The Wall Street Journal. That may dampen the potential sales impact for J&J, although it may add to revenue ahead of Risperdal’s expected patent expiration in 2008. The drug had 2006 sales of $4.2 billion, $2.5 billion of it in the US.

Other companies applying for some similar label changes include Eli Lilly, which markets Zyprexa, and Bristol-Myers Squibb, maker of Abilify. All antipsychotics, including the newer ones, accounted for about $11.7 billion in sales last year, an 11% rise over 2005, according to IMS Health.

What the agency’s decision is likely to do is stoke a debate over whether such drugs are safe for teens. There is also a disagreement over what symptoms warrant use of the powerful, next-generation medicines, a debate J&J’s short-term studies do not resolve.

These questions could make for a tricky marketing proposition. Risperdal is marketed in the US by Janssen and promoted by McNeil Pediatrics, another J&J division. Cline Davis & Mann handles professional advertising, while CommonHealth Consumer Group works on DTC. Neither agency was immediately available for comment.

The Risperdal approval was based on two short-term (6 to 8 weeks) studies in young people. Side effects included drowsiness, fatigue, increase in appetite, as well as increase in blood sugar, which can cause diabetes. Some may need regular blood sugar testing, the company said.

Weight gain, type 2 diabetes and cholesterol are common among adults taking atypical antipsychotics, and young people may be more sensitive to these effects. The firm is doing longer-term pediatric trials.

Invega (paliperidone), a once-daily extended-release version of Risperdal, was launched by J&J this year, and the company hopes to switch Risperdal patients to the new drug.