Eli Lilly and Co said Thursday its Zyprexa drug performed better than risperidone, the most widely prescribed antipsychotic, in the treatment of schizophrenia in a clinical study.
In a double-blind study of 339 patients, on serveral key criteria that define a novel antipsychotic, patients receiving Zyprexa reported statistically significant differences compared with those receiving risperidone, Lilly said.
Belgium's <Janssen Pharmaceutica>, which makes risperidone under the Risperdal brand name, criticized the Lilly study.
Janssen said dosages of Zyprexa were greater than dosages of risperidone, and the group used in determining a relapse rate was too small.
Lilly said Zyprexa and risperidone showed effectiveness in reducing the severity of schizophrenia after eight weeks of treatment.
At 28 weeks, 55 percent of Zyprexa patients reported improvements of at least 30 percent on a gauge that measures the severity of schizophrenia, compared with 43 percent of risperidone-treated patients, Lilly said.
Also, Zyprexa-treated patients after 28 weeks showed a significant improvment in preventing a relapse of psychotic symptoms, Lilly said.
Dosing ranges for Zypreza were five to 20 milligrams per day, while the dosing range for risperidone was four to 12 milligrams per day, it said.
Lilly said the most common side effects from Zyprexa were dry mouth, excessive appetite and drowsiness.
Interim results of the study were presented December 11 at the American College of Neuropsychopharmacology in San Juan, Puerto Rico, Lilly said.
Janssen said it was premature to draw any definitive conclusions from the trial witout evaluating the methodology and statistical analysis. It said it would begin its own investigation in early 1997 to compare Zyprexa and risperidone.
Janssen is a unit of Johnson and Johnson <JNJ.N>.