SAN JUAN, PUERTO RICO - The manufacturers of risperidone and olanzapine, two new drugs for the treatment of schizophrenia, are waging a spirited battle over which of these "atypical antipsychotics" is the best for the treatment of the disorder.
About 1% of the population -- 2.5 million people in the United States -- suffer from schizophrenia. Symptoms of the disorder include "positive" symptoms: hallucinations, delusions and hearing voices; and "negative" symptoms: social withdrawal and little or inappropriate emotional responses.
One head-to-head trial between the two drugs was presented at the annual meeting of the American College of Neuropsychopharmacology here. That study was sponsored by Eli Lilly Company, the manufacturer of olanzapine -- the newer drug on the market, which was approved in 1995.
Pierre Tran, a scientist with Lilly Research Laboratories, said the study of 297 patients showed that olanzapine was superior to risperidone in several areas, including superior efficacy in maintenance treatment in the 28-week doubleblind study.
Tran also said that olanzapine caused a lower incidence of extrapyramidal events (EPS) -- parkinsonian-like movement disorders, less sexual dysfunction, and less treatment-associated prolactinemia.
"A statistically significant greater proportion of male risperidone-treated patients has experienced treatmente-mergent hypersalivation, palpitations, blurred vision and delayed ejaculation," he said.
About 10% of olanzapine patients experienced EPS, compared to more than 21% on risperidone, Tran found.
However, many of Tran's patients on risperidone were administered levels of drug that are now considered too high for optimal treatment. The median dosage was 7.3 mg, but dozens of patients received dosages above 8 mg.
Tran said doctors were permitted to treat patients with up to 12 mg, following the package insert instructions that came with risperidone when his trial was begun in 1994.
At another poster session just a few feet from Tran's presentation, Phillippe Lemmens of the Jannsen Research Foundation in Belgium said that studies of Jannsen's risperidone showed that higher dosages above 8 mg a day were of no benefit to the patient.
Lemmens scrutinized data from a dozen double-blind studies that included more than 2,000 patients with schizophrenia who were treated with risperidone. "The most effective doses of risperidone were 4 mg, 6 mg and 8 mg/day. At these doses 65% of the patients were clinically improved," he reported. The average dose prescribed for patients with schizophrenia is 4.7 mg, a dose also associated with fewer EPS episodes.
In just a few years since it was approved for treatment of schizophrenia, risperidone has become the leading drug in the field, spokesmen for Jannsen said. They criticized the report by Lilly's Tran as "irrelevant in today's world because it doesn't reflect clinical practice." The higher risperidone dosages used in Tran's study would tend to increase adverse side effects, they said.
In other scientific presentations, both olanzapine and risperidone were compared to conventional antipsychotic drugs, such as haloperidol, and it was determined that patients taking the "atypicals" had fewer side effects and better outcomes than those taking the older drugs.
Both Lilly and Jannsen are continuing to enrol patients in further studies aimed at showing the benefits of their compounds.
Copyright © 1997 Maclean Hunter Publishing Limited
Reprinted with permission.
Internet Mental Health (www.mentalhealth.com) copyright © 1995-2011 by Phillip W. Long, M.D.