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What is Zyprexa?

Zyprexa (olanzapine) is manufactured by Eli Lilly and Company. It is a new "atypical" antipsychotic medication that received FDA approval for the treatment of schizophrenia in September 1996.

How does Zyprexa work?

Researchers and clinical psychopharmacologists do not fully know what causes schizophrenia. It is known, however, that several neurotransmitters in the brain are altered in persons with schizophrenia. Zyprexa works to reduce symptoms of schizophrenia by blocking various serotonin and dopamine receptors. It blocks the serotonin (5HT2A) receptor more potently than the dopamine (D2) receptor. In animal studies, Zyprexa is more potent at blocking serotonin and dopamine than Clozaril. Animal and human studies, however, indicate that Zyprexa may have a greater risk of causing extrapyramidal side effects than Clozaril. Extrapyramidal side effects include slowing of voluntary movement, expressionless face, rigidity and tremor of arms and head, abnormal toxicity of muscle tissues, and restlessness.

What is the standard dose of Zyprexa?

Oral doses of 10 mg daily have been effective for most patients in the treatment of schizophrenia. Zyprexa can be dosed once a day at bedtime. This is an advantage over Clozaril which needs to be dosed two or more times a day in most patients. Zyprexa is available by prescription from your pharmacy in 5.0 mg, 7.5 mg and 10 mg tablets. 10 mg has been an effective starting dose in most patients.

How is Zyprexa different from Clozaril?

Zyprexa differs from Clozaril in side effects. Zyprexa does not cause seizures or agranulocytosis, a serious deficiency of a type of white blood cells that could be fatal. Although Clozaril works very well to treat schizophrenia, it requires a weekly blood draw and weekly prescription refills because of the monitoring for agranulocytosis. Weekly blood drawing and refills are not necessary with Zyprexa. Zyprexa also differs from Clozaril in that it does not cause excessive drooling. Zyprexa may produce more extrapyramidal side effects (tremor, akathisia, and muscle stiffness) than Clozaril, however. Zyprexa has not been directly compared to Clozaril in clinical studies in patients, so it is not now known which drug will be better for certain patients with schizophrenia.

What about side effects?

Older antipsychotic medications have been difficult for patients to continue to take because they cause side effects like weight gain, fatigue, stiff body movement, and blurred vision. Newer antipsychotics like Zyprexa do not cause as much blurred vision or dryness of the mouth, or as frequent stiff body movements.

How is Zyprexa different from Risperdal?

There have been no direct clinical comparisons between Zyprexa and Risperdal. Eli Lilly and Company is currently conducting such a study, however. This study is an international effort, and results may be available in the next year.

How will Zyprexa be administered?

Zyprexa is available from your pharmacy as oral tablets. The strengths available are 5 mg, 7.5 mg and 10 mg tablets. The drug is to be taken orally.

Reviewed by Dale Grothe, Pharm D., National Institute of Mental Health, and David Daniel, MD, Arlington, VA. November 1996