CHICAGO (AP) -- A drug that has become one of the first-line treatments for schizophrenia since the mid-1990s is not much better than older and cheaper medication, a surprising new study found.

The study was paid for by Eli Lilly & Co., maker of the newer drug, olanzapine, sold as Zyprexa.

Earlier, shorter studies showed it was less likely to cause the tremors associated with older drugs such as haloperidol. But some previous research compared Zyprexa against only haloperidol, which typically is combined with another drug, benztropine, to reduce the risk of tremors.

The latest study, conducted for a year at 17 veterans hospitals, tested Zyprexa against the two-drug combination and found that Zyprexa patients fared only slightly better on scores of restlessness and mental function but had about the same degree of tremors.

Zpyrexa costs more than $8 a day versus about 10 cents a day for the two-drug combination.

In the study, Zyprexa patients had $3,000 to $9,000 more in yearly expenses -- mostly because of higher drug costs and more hospital stays -- and the drug caused substantial weight gain, a known side effect.

Doctors and patients should consider those disadvantages when selecting treatment, instead of assuming Zyprexa is superior, said Dr. Robert Rosenheck, the study's lead author and director of the Veterans Affairs Department's Northeast Program Evaluation Center in West Haven, Conn.

"I had read the literature and believed that this drug would do better than haloperidol, so I was very surprised," Rosenheck said. The findings show "we may not be getting as much out of this as we thought we were."

The study appears in Wednesday's Journal of the American Medical Association.

Americans spend about $2 billion annually on Zyprexa.

The study involved 309 mostly male veterans with schizophrenia, a mental illness that affects about 2.2 million Americans. Patients took either daily doses of Zyprexa or the haloperidol-benztropine combination for a year.

About 6 percent of Zyprexa patients had moderate or marked restlessness compared with about 9.6 percent of the double-drug group. Zyprexa patients also had slightly better mental function, but there was no difference in tremors between the two groups.

At 12 months, nearly 25 percent of Zyprexa patients reported weight gain, compared with about 8 percent of the other group.

Dr. Alan Breier, Lilly's chief medical officer, blamed the disappointing results on the study's design. He said that not enough patients were recruited and that they were sicker than typical schizophrenics.

Copyright 2003 The Associated Press. All rights reserved.