Zyprexa vs. Risperdal Test Results

Eli Lilly & Co. disclosed results of a study that suggested Lilly's Zyprexa schizophrenia drug is more effective than the current leading treatment, Johnson & Johnson's Risperdal.

J&J challenged the study's findings as seriously flawed, however. Lilly's release of the study -- which it conducted -- marks the first big salvo in a marketing effort by which the Indianapolis pharmaceutical concern is seeking to claim a big portion of the market for antipsychotic drugs.

Zyprexa, which was cleared for sale in the U.S. in October, will compete with older generic schizophrenia medications such haloperidol, as well as newer drugs like Sandoz AG's Clozaril and J&J's market-leading Risperdal. The world-wide market for such antipsychotic drugs totals about $1 billion, and is expected to grow significantly in coming years.

In a presentation at a high-profile medical conference in Puerto Rico, Lilly said the study showed that Zyprexa provided more benefit to schizophrenic patients, as measured by a number of criteria.

A greater proportion of schizophrenia patients made it through the full 28-week trial if they were treated with Lilly's Zyprexa, suggesting the new drug produced fewer unpleasant side effects. Most antipsychotic drugs produce strong side effects, such as uncontrollable limb movements.

Eight weeks into the trial, Lilly said, the two antipsychotic drugs showed "comparable effectiveness" in reducing the severity of the patients' symptoms. But when measured 28 weeks into the test, the results no longer compared equally: in the trial, 55% of the Zyprexa patients reported at least a 30% reduction in the severity of their symptoms, compared with 43% of the patients being treated with Risperdal.

It said Zyprexa generated fewer incidences of certain side effects, and said the test on 339 subjects suggested that Zyprexa patients were somewhat less likely to have suffered a relapse.

J&J's Janssen Pharmaceutical unit, the maker of Risperdal, hurried to point out what it called "important concerns regarding the study's design and its findings."

Among other things, it said, the dosage of Risperdal used in the study was substantially higher than the average dose used in standard clinical practice.

"The problem with these [antipsychotic] drugs is that if you increase the dose even slightly," noted independent industry analyst Hemant Shah, "you'll get an increase in side effects."

Indeed, Lilly's study turned up a substantially higher incidence of side-effects than ever seen in Janssen's studies, the J&J unit said. It said the data on relapse rates are open to question as well.

Janssen said it plans "head-to-head" trial of the two drugs next year "at dosages commonly used in clinical practice."

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