June 5 (Bloomberg) -- Bristol-Myers Squibb Co. asked U.S. regulators to clear Abilify for schizophrenia in teenagers, joining Johnson & Johnson and Eli Lilly & Co. in a push to expand the $15 billion-a-year market for antipsychotic medicines.

The U.S. Food and Drug Administration will consider whether Abilify, approved for adult use in 2002, can safely treat patients ages 13 to 17, Bristol-Myers said today. The FDA typically reviews pediatric medicines within six months.

About 1 in 100 people have schizophrenia, which causes hallucinations and distorted thinking, and a third develop it in adolescence, doctors say. Use of antipsychotic drugs for younger patients has risen sharply in recent years, prompting concern among some doctors and parents about side effects including weight gain and diabetes.

``There's no gold standard for treating schizophrenia in teens, and the first company to get FDA approval for this will have an edge in this very crowded market,'' said Les Funtleyder, an analyst at Miller Tabak & Co. in New York, in a telephone interview.

Sales of Abilify surged 41 percent last year to $1.3 billion, the biggest increase among antipsychotics, helped by studies showing it caused less weight gain than competing drugs. Sales of Zyprexa grew 3.8 percent to $4.4 billion last year. J&J's Risperdal generated $4.2 billion, an 18 percent increase.

Unapproved Use

About 15 percent of antipsychotic sales came from doctors writing prescriptions for uses currently not approved by the FDA, including for adolescents, analysts say. Once the FDA clears a drug for sale, doctors are free to prescribe it for unapproved, ``off-label'' uses. Drugmakers can't promote such uses.

``I would expect Abilify to gain the most prescriptions from an approval for adolescent use because younger patients appear to be more susceptible to weight gain than adults,'' said Jeffrey Lieberman, chairman of psychiatry at Columbia University in New York.

The shares of Bristol-Myers, based in New York, fell 2 cents to $30.42 at 4:03 p.m. in New York Stock Exchange composite trading. The stock has climbed 16 percent this year. Earlier the shares reached $30.55, the highest in more than three years.

J&J of New Brunswick, New Jersey, said the FDA may decide this month whether its antipsychotic Risperdal can be used for schizophrenia and bipolar disorder in adolescents. FDA action on Indianapolis-based Lilly's antipsychotic Zyprexa was slowed in April, when the agency requested more time to review that pill for the same two conditions.

Sixfold Increase

Antipsychotic prescriptions for patients age 20 or younger increased sixfold from 1993 to 2002, from 201,000 to 1.22 million, according to a study published last year in the Archives of the Journal of the American Medical Association.

Prescriptions of the drugs for teenagers are now written mostly by psychiatrists. FDA approval would encourage pediatricians and primary care physicians to prescribe the drugs as well, said Mark Olfson, a professor at Columbia. Use of Prozac and other antidepressants for younger patients soared after the FDA cleared those drugs for children.

``These antipsychotics will follow the same path as Prozac,'' Olfson said. ``The FDA label gives physicians outside psychiatry some reassurance and confidence in prescribing these medications.''

That prospect is opposed by some doctors, including psychiatrist Stefan Kruszewski. After a report on May 24 that the FDA was reviewing the medicines for adolescent use, Kruszewski wrote FDA Commissioner Andrew von Eschenbach to urge rejection of the applications.

`False Sense of Security'

``There is a very likely possibility that the FDA approval of a teenage indication will provide a false sense of security,'' Kruszewski, of Harrisburg, Pennsylvania, wrote in a copy of the letter he provided by e-mail. ``Approval would function as the means by which aggressive pharmaceutical marketing could easily persuade more practitioners to prescribe more potent medications.''

Atypical antipsychotics, the class of drugs that includes Abilify, Risperdal and Zyprexa, came on the market in the mid-1990s. The new products were touted as causing fewer of the neurological side effects that made users of earlier medications, such as Haldol, tremble, doze off and jerk involuntarily. Antipsychotics are used to treat psychological conditions including schizophrenia and bipolar disorder.

Abilify was found to be safe and effective in teens from age 13 to 17 at doses of 10 milligrams and 30 milligrams, with 85 percent of patients remaining on the drug for six weeks, according to a study released May 24 at a medical meeting.

The study also found that 4.8 percent of teens on a 10- milligram dose of Abilify and 6 percent of patients on a 30- milligram dose gained 7 percent or more of their weight, compared with 1 percent for the placebo.

Lilly Drug Delayed

Lilly's request to sell Zyprexa to treat schizophrenia and bipolar disorder in teens was delayed by the FDA on April 30, the company said. Lilly received a so-called approvable letter indicating the agency needs more time to analyze data and to determine the drug's prescribing information.

Children ages 13 to 18 taking Zyprexa were almost twice as likely to have significant weight gain as adults taking the drug, according to a study released at a medical meeting last week. The study found 65 percent of adolescents gained 7 percent or more of their weight, compared with 36 percent of adults. involved and the drug isn't approved for use in teens.

Researchers halted tests of Zyprexa early in a different study of antipsychotics in teens sponsored by the National Institute of Mental Health, according to documents posted on the U.S. government's Web site tracking clinical trials. The trial, completed in July of 2006, was designed to compare safety and efficacy of Zyprexa, Risperdal and an older drug, known generically as molindone.

Zyprexa Use Stopped

The data safety monitoring board stopped giving study participants Zyprexa in November 2005 due to side effects including weight gain, said Adelaide Robb, a psychiatrist with Children's National Medical Center in Washington, D.C.

A spokeswoman for the National Institute of Mental Health declined to comment on why the Zyprexa arm was halted. Lilly spokeswoman Carole Puls declined to comment on the NIMH study, saying the company wasn't involved and the drug isn't approved for use in teens.

To contact the reporter on this story: Lisa Rapaport in New York at Lrapaport1@bloomberg.net

Last Updated: June 5, 2007 16:18 EDT