Zyprexa has been approved for the treatment of the symptoms of psychotic disorders.

Lilly submitted data from extensive clinical trials involving more than 3,100 people in 22 countries. According to data gathered from these studies, subjects treated with Zyprexa reported statistically significant differences across several key test instruments measuring symptoms of schizophrenia when compared with placebo.

In clinical trials, Zyprexa was superior to placebo in treating the symptoms of schizophrenia. The efficacy of Zyprexa in the management of the symptoms of psychotic disorders was established in two six-week placebo controlled trials of schizophrenic inpatients.

Subjects were assessed using several test instruments, including the Brief Psychiatric Rating Scale (BPRS), an 18-item inventory of symptoms traditionally used to evaluate the effects of drug treatment in psychosis. The BPRS score was extracted from the Positive and Negative Syndrome scale (PANSS), a 30-item rating instrument that evaluates each symptom item on a scale of 1 (absent) to 7 (extreme). The BPRS psychosis cluster assessed psychotic symptoms, such as conceptual disorganization, hallucinatory behavior, suspiciousness, and unusual thought content.

A second assessment, the Clinical Global Impression (CGI), measures the overall severity of the illness. In addition, subjects were evaluated on the PANSS and the Scale for Assessing Negative Symptoms (SANS).

In a six-week, placebo-controlled trial involving 149 subjects, subjects received either placebo or a fixed dose of Zyprexa at 1 and 10 mg/day. In this trial, Zyprexa at 10 mg/day (but not 1 mg/day) was superior to placebo on the PANSS total score, the BPRS total, the BPRS psychosis cluster, the PANSS negative symptom sub-scale, and on CGI severity.

In a six-week, placebo-controlled trial involving 253 subjects, subjects received placebo or one of three fixed dose ranges of Zyprexa (5 +/- 2.5 mg/day, 10 +/- 2.5 mg/day, 15 +/- 2.5 mg/day). The two highest Zyprexa doses (but not the lowest) were superior to placebo on the BPRS total score, BPRS psychosis cluster, and CGI severity score. The highest Zyprexa dose was statistically superior to placebo on the SANS.

The overall rate of early discontinuation due to an adverse event was comparable to placebo.

Many currently available older antipsychotic medications, although effective, have been linked to extrapyrimidal syndrome (EPS) events, including abnormal muscle spasms, Parkinson's-disease-like symptoms, abnormal jerking or writhing, and an inability to sit still.

Clinical studies have associated Zyprexa with a low incidence of EPS. In clinical trials, treatment-emergent EPS assessed by formal rating scales occurred at incidences comparable to placebo. As assessed by these scales, the incidence of EPS did not increase as the dose of Zyprexa was increased.

As with all antipsycotics, Zyprexa was associated with some side effects. In acute-phase, placebo-controlled trials, the most frequently observed treatment emergent events associated with Zyprexa at an incidence statistically greater than placebo were somnolence, dizziness, and weight gain. The incidence of elevated hepatic transaminase levels was greater with Zyprexa; these elevations were generally transient and asymptomatic. About 1% of subjects in clinical trials discontinued treatment due to transaminase increases. Other commonly observed adverse events associated with the use of Zyprexa were constipation, personality disorder, and postural hypotension; these event rates were not statistically greater than placebo. In only one analysis of a placebo-controlled study, only one specific form of EPS, akathesia, was reported significantly more often with Zyprexa compared with placebo.

Schizophrenia is a clinical syndrome marked by the presence of positive psychotic symptoms, such as delusions and hallucinations, and negative symptoms, such as apathy, diminished emotions, and low motivation. People with schizophrenia can have difficulty distinguishing fantasy from reality, thinking clearly, and managing emotions. They may also lose their social skills, their schooling or jobs, or their ability to communicate.

Schizophrenia is one of the most chronic and debilitating of the mental illnesses, striking about 1% of the world's population.