Olanzapine

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 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.

It is approved by the FDA for the following indications:

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.

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.

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.