What is olanzapine, and how does it work (mechanism of action)?
Olanzapine belongs to a drug class known as atypical antipsychotics. Other members of this class include clozapine (Clozaril), risperidone (Risperdal), aripiprazole (Abilify) and ziprasidone (Geodon). The exact mechanism of action of olanzapine is not known. It may work by blocking receptors for several neurotransmitters (chemicals that nerves use to communicate with each other) in the brain. It binds to alpha-1, dopamine, histamine H-1, muscarinic, and serotonin type 2 (5-HT2) receptors. Olanzapine was approved by the FDA in 1996.
What brand names are available for olanzapine?
Zyprexa, Zyprexa Zydis, Zyprexa Relprevv
Is olanzapine available as a generic drug?
Do I need a prescription for olanzapine?
What are the side effects of olanzapine?
- Elderly patients with dementia related psychosis treated with antipsychotics are at an increased risk of death.
- When using olanzapine and fluoxetine in combination, also refer to the boxed warning section of the package insert for Symbyax.
Common side effects
Common side effects seen with olanzapine are:
- an inability to sit still (akathisia),
- dry mouth,
- orthostatic hypotension,
- tremor, and
- weight gain.
Several disorders of movement also may occur with olanzapine, for example, extrapyramidal effects (sudden, often jerky, involuntary motions of the head, neck, arms, body, or eyes). Tardive dyskinesia (involuntary movements of the mouth, tongue, jaw, or eyelids) also may occur in 1 in 100 patients receiving olanzapine. Some cases can be irreversible. The likelihood of developing tardive dyskinesia increases with prolonged treatment.
There may be an increased risk of elevated blood sugar levels and diabetes with olanzapine as well as the other antipsychotic medications in its class. Patients should be tested during treatment for elevated blood sugar. Additionally, persons with risk factors for diabetes, including obesity or a family history of diabetes, should have their fasting levels of blood sugar tested before starting treatment and periodically throughout treatment to detect the onset of diabetes. Any patient developing symptoms that suggest diabetes during treatment should be tested for diabetes.
Schizophrenia is the most disabling mental illness.
What is the dosage for olanzapine?
The usual oral dose of olanzapine for treating schizophrenia is 10-20 mg once daily. Therapy is initiated with 5-10 mg/day, and the dose may be increased by 5 mg a day at weekly intervals. The maximum dose is 20 mg daily. The recommended dose of extended release injection is 150-405 mg every 2 or 4 weeks.
Treatment of bipolar disorder usually is initiated with oral doses of 10-15 mg once daily. The dose may be increased by 5 mg daily at 24 hour intervals. The maximum dose is 20 mg daily.
The usual dose for treating agitation due to schizophrenia or bipolar disorder is 10 mg administered by intramuscular injection (immediate release). Additional 10 mg doses may be administered, but the efficacy of total doses greater than 30 mg daily have not been adequately evaluated.
The recommended treatment for resistant depression is 5-20 mg of olanzapine combined with 20-50 mg of fluoxetine once daily in the evening while the recommended treatment for depression associated with bipolar disorder is 5-12.5 mg olanzapine combined with 20-50 mg fluoxetine once daily in the evening.
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Which drugs or supplements interact with olanzapine?
Carbamazepine (Tegretol) can reduce blood concentrations of olanzapine, possibly necessitating higher doses of olanzapine. Other drugs that may also reduce blood levels of olanzapine are omeprazole (Prilosec) and rifampin.
Smoking may reduce blood concentrations of olanzapine.
Ciprofloxacin (Cipro), diltiazem (Cardizem, Dilacor, Tiazac), erythromycin, and fluvoxamine (Luvox) may have the opposite effect, that is, they may increase blood levels of olanzapine, and the dose of olanzapine may need to be reduced.
Olanzapine can cause orthostatic hypotension, a drop in blood pressure upon standing up that may cause dizziness or even fainting. Taking olanzapine with either diazepam (Valium), other related benzodiazepines or alcohol can exaggerate the orthostatic hypotension caused by olanzapine.
Is olanzapine safe to take if I’m pregnant or breastfeeding?
There are no adequate studies of olanzapine in pregnant women. Olanzapine should only be administered to pregnant women if the benefits justify the unknown risks.
What else should I know about olanzapine?
What preparations of olanzapine are available?
Tablets: 2.5, 5, 7.5, 10, 15, 20 mg. Tablets (orally disintegrating): 5, 10, 15, 20 mg. Injection (immediate release): 10 mg vial. Suspension for Injection (extended release): 210, 300, and 405 mg (powder).
How should I keep olanzapine stored?
Tablets should be kept at room temperature, 20 C – 25 C (68 F – 77 F). Suspension is stored at room temperature not to exceed 30 C (86 F).