Olanzapine, sold under the brand name Zyprexa among others, is an atypical antipsychotic primarily used to treat schizophrenia and bipolar disorder. It is also sometimes used off-label in cancer patients for treatment of chemotherapy-induced nausea and vomiting and as an appetite stimulant. For schizophrenia, it can be used for both new-onset disease and long-term maintenance. It is taken by mouth or by injection into a muscle. Common side effects include feeling tired, dizziness, constipation, dry mouth, and restlessness. Other side effects include low blood pressure with standing, allergic reactions, neuroleptic malignant syndrome, diabetes mellitus, seizures, and tardive dyskinesia. In older people with dementia, its use increases the risk of death. Use in the later part of pregnancy may result in a movement disorder in the baby for some time after birth. Although its mechanism of action is not entirely clear, it is known to block dopamine and serotonin receptors. Olanzapine was patented in 1991 and approved for medical use in the United States in 1996. It is available as a generic medication. In 2023, it was the 167th most commonly prescribed medication in the United States, with more than 3 million prescriptions. It is on the World Health Organization's List of Essential Medicines.
Medical uses It is approved by the FDA for the following indications:
schizophrenia. acute treatment of manic or mixed episodes associated with bipolar I disorder and maintenance treatment of bipolar I disorder. adjunct to lithium or valproate in the treatment of manic or mixed episodes associated with bipolar I disorder. combination olanzapine/fluoxetine (Symbyax) for the treatment of depressive episodes of bipolar I disorder and for treatment-resistant depression. combination olanzapine/samidorphan (Lybalvi) for the treatment of schizophrenia and bipolar I disorder. Lybalvi suppresses the metabolic side effect of olanzapine. More precisely, olanzapine produces weight gain of about 9 kg (20 pounds) in the short-term, which typically increases to around 23–45 kg (50–100 pounds) following long-term use. In contrast, Lybalvi only triggers roughly 5 kg (11 pounds) before subsiding. In the United Kingdom and Australia, it is approved for schizophrenia, moderate to severe manic episodes, alone, or in combination with lithium or valproate and the short-term treatment of acute manic episodes associated with bipolar I disorder. Olanzapine is also used off-label for the treatment of chemotherapy-induced nausea and vomiting.
Schizophrenia The first-line psychiatric treatment for schizophrenia is antipsychotic medication. Olanzapine appears to be effective in reducing symptoms of schizophrenia, treating acute exacerbations, and treating early-onset schizophrenia. The usefulness of maintenance therapy, however, is difficult to determine, as more than half of people in trials quit before the 6-week completion date. Treatment with olanzapine (like clozapine) may result in increased weight gain and increased glucose and cholesterol levels when compared to most other second-generation antipsychotic drugs used to treat schizophrenia.
Bipolar disorder Olanzapine is recommended by the National Institute for Health and Care Excellence as a first-line therapy for the treatment of acute mania in bipolar disorder. Other recommended first-line treatments are aripiprazole, haloperidol, quetiapine, and risperidone. It is recommended in combination with fluoxetine as a first-line therapy for acute bipolar depression, and as a second-line treatment by itself for the maintenance treatment of bipolar disorder. The Network for Mood and Anxiety Treatments recommends olanzapine as a first-line maintenance treatment for bipolar disorder and the combination of olanzapine with fluoxetine as a second-line treatment for bipolar depression. A review on the efficacy of olanzapine as maintenance therapy in people with bipolar disorder was published in 2006. A 2014 meta-analysis concluded that olanzapine with fluoxetine was the most effective among nine treatments for bipolar depression included in the analysis.
Specific populations
Pregnancy and lactation Olanzapine is associated with the highest placental exposure of any atypical antipsychotic. Despite this, the available evidence suggests it is safe during pregnancy, although the evidence is insufficiently strong to say anything with a high degree of confidence. Olanzapine is associated with weight gain, which according to recent studies, may put olanzapine-treated patients' offspring at a heightened risk for neural tube defects (e.g. spina bifida). Breastfeeding in women taking olanzapine is advised against because olanzapine is secreted in breast milk, with one study finding that the exposure to the infant is about 1.8% that of the mother.
Elderly Citing an increased risk of stroke, in 2004, the Committee on the Safety of Medicines in the UK issued a warning that olanzapine and risperidone, both atypical antipsychotic medications, should not be given to elderly patients with dementia. In the U.S., olanzapine comes with a black box warning for increased risk of death in elderly patients. It is not approved for use in patients with dementia-related psychosis. A BBC investigation in June 2008 found that this advice was being widely ignored by British doctors. Evidence suggested that the elderly are more likely to experience weight gain on olanzapine compared to aripiprazole and risperidone.
Adverse effects
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