DRUG CLASS AND MECHANISM: Olanzapine is a drug that is used to treat schizophrenia and acute manic episodes associated with bipolar I disorder. 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.
PRESCRIPTION: Yes
GENERIC AVAILABLE: Yes
PREPARATIONS: 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).
STORAGE: Tablets should be kept at room temperature, 20-25 C (68-77 F). Suspension is stored at room temperature not to exceed 30 C (86 F).
PRESCRIBED FOR: Olanzapine is used for treating schizophrenia and acute mixed or manic episodes associated with bipolar disorder. It also is used as maintenance therapy for bipolar disorder and treating agitation due to schizophrenia or bipolar disorder. Olanzapine also is used in combination with fluoxetine (Prozac) for treatment of resistant depression and treatment of depression associated with bipolar disorder.
DOSING: 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.
DRUG INTERACTIONS: 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.
PREGNANCY: 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.
