May 24 (Bloomberg) -- Bristol-Myers Squibb & Co. says its schizophrenia drug didn't cause significant weight gain or sexual dysfunction in most teens in six-week trials, a finding that the company will use to seek U.S. marketing clearance.

Eli Lilly & Co. said its similar drug caused 65 percent of adolescents to gain weight, double the rate in adults, the company said. Studies for Bristol's Abilify and Lilly's Zyprexa were presented yesterday at a medical meeting in San Diego.

Bristol, Lilly and Johnson & Johnson are racing to get the drugs cleared for use in teenagers. Lilly said its bid to sell Zyprexa, the top-selling antipsychotic, in teens has been delayed by U.S. regulators, and J&J said its Risperdal may be approved as early as June. No drugs are currently cleared in the U.S. to treat schizophrenia or bipolar disorder in teens.

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

Drugmakers sold more than $15 billion in antipsychotic drugs last year, according to data compiled by Bloomberg.

The shares of Bristol-Myers, based in New York, rose 3 cents to $30.03 at 4:02 p.m. in New York Stock Exchange composite trading. J&J, based in New Brunswick, New Jersey, fell 33 cents to $63.48. Indianapolis-based Lilly fell 21 cents to $59.19. The studies were released after the close of U.S. markets yesterday.

Not Better or Safer

Atypical antipsychotics first came on the market in the mid- 1990s, touted as causing fewer of the neurological side effects that made users of earlier medications like Haldol and Thorazine tremble, doze off and jerk involuntarily.

Recent government-funded studies examining use of the drugs in adult schizophrenics suggest they are neither safer nor more effective than the older medications they replaced, yet they cost 10 to 20 times more.

Their use in children has risen sharply in recent years, prompting concern among doctors and parents because the drugs cause weight gain and trigger diabetes and aren't approved for use in children. Lilly is being sued by the attorneys general of Utah and Montana, in part for inappropriately marketing Zyprexa to children with psychiatric conditions.

Lilly said yesterday it received a so-called approvable letter for Zyprexa from the FDA on April 30. Such letters are typically used by the agency to tell drugmakers what's needed to get clearance to market the drug. The FDA wanted more time to analyze data on the medication and discuss its prescribing guidelines, the Indianapolis-based company said.

`Not Required'

The company said it didn't release information about the letter when it was received because it wasn't required to do so under U.S. securities law. The company is seeking approval of Zyprexa for both schizophrenia and bipolar disorder in teens.

``We are one step closer to being able to provide an answer for an unmet medical need and make sure clinicians have more information to make a difficult treatment decision about this patient population,'' said Carole Puls, a Lilly spokeswoman, in a telephone interview yesterday.

Schizophrenia causes distorted thinking, hallucinations and an inability to feel normal emotions. About 1 in 100 people have the disorder, and a third of them develop it in adolescence, said Robert Findling, the author of the Abilify study and professor of psychiatry at Case Western Reserve University in Cleveland, Ohio.

Abilify was found in the study 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 through six weeks.

Six-Week Study

In the study, 13 percent of teens taking the smaller dose and 21.6 percent of those taking the larger dose experienced neurological side effects after six weeks, compared with 5 percent of patients taking placebos.

These numbers worry Stefan Kruszewski, a child and adolescent psychiatrist in Harrisburg, Pennsylvania, who serves as a consulting expert in insurance and pharmaceutical fraud litigation.

``The incidence of these neurological problems, even with relatively low doses of Abilify, were as much as four times that of placebo,'' Kruszewski said in a phone interview yesterday.

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

``If that were to continue over the course of 12 months, it could pose a serious medical problem in terms of obesity and cardiovascular complications for some children,'' Kruszewski said.

Zyprexa was found to be effective in treating schizophrenia and bipolar disorder in 13- to 18-year-olds.

Effective in Teens

``Most kids right now are being treated with atypical antipsychotics even though the drugs aren't approved for this use,'' Findling said in a telephone interview yesterday. FDA approval of Ability ``would give physicians a sense of confidence about the scientific data of this use and also give parents some reassurance.''

The Abilify data was presented at a meeting of the American Psychiatric Association this week. Bristol-Myers spokesman Jeffrey Macdonald declined to comment on how soon the company would file an application with the Food and Drug Administration for its approval.

J&J asked the FDA to approve Risperdal for schizophrenia and bipolar disorder in teens on Dec. 21, company spokesman Srikant Ramaswami said in a telephone interview yesterday. Regulators typically take six months to review pediatric medicines, he said.

Risperdal reduced symptoms of schizophrenia in a significantly higher number of teens than a placebo, according to an abstract of a six-week study of 160 patients J&J presented at the same medical meeting.

The study was submitted to the FDA to support approval of Risperdal for adolescent schizophrenia, J&J said. The company hasn't made public any studies supporting its application to use the drug for teen bipolar disorder.

`Significant' Weight Gain

In the Zyprexa study of 454 patients, children between 13 and 18 were more than twice as likely to have significant weight gain as adults taking the drug, with 65 percent of adolescents gaining 7 percent or more of their weight, compared with 36 percent in adults.

Zyprexa also caused higher levels of prolactin elevation, a condition linked in studies to sexual dysfunction, in teens than in adults, according to a separate study by Lilly of 454 patients with schizophrenia and bipolar disorder.

``Head-to-head trials of these drugs haven't been done yet to know which one will be most appropriate for which adolescent patient, or why,'' Findling said. ``I'm not sure how many physicians will change their prescribing habits based on one getting FDA approval specifically for adolescents.''

U.S. regulators wanted more time to analyze data and discuss Zyprexa's prescribing information, Lilly medical officer Sara Corya said. She didn't have a timeline for when a decision will be reached. There are no ongoing studies of the drug in children, she said.

Lilly's Zyprexa generated $4.4 billion in sales last year, and Johnson & Johnson's Risperdal had sales of $4.2 billion. Sales of Abilify climbed 41 percent to $1.3 billion.

Lilly's Zyprexa has lost market share in the past two years because of negative publicity about weight gain induced by the drug, analysts have said.

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

Last Updated: May 24, 2007 19:12 EDT