Medications and Drugs
Medical and Pharmacy Editor: Jay W. Marks, MD
GENERIC NAME: olanzapine
BRAND NAME: Zyprexa, Zydis
DRUG CLASS AND MECHANISM: Olanzapine is a medication 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: No
PREPARATIONS: Tablets: 2.5, 5, 7.5, 10, 15, 20 mg. Intramuscular
Injection: 10 mg vial.
STORAGE: Tablets should be kept at room temperature, 20-25°C
(68-77°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 for treating schizophrenia is 10 mg once
daily. Therapy is initiated with 5-10 mg/day and the dose may be increased by 5
mg a day in weekly intervals. Doses greater than 10 mg daily have not been shown
to be more effective than 10 mg daily. The safety and efficacy of doses greater
than 20 mg daily have not been evaluated.
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.
Doses greater than 20 mg daily have not been evaluated. In clinical trials,
doses of 5-20 mg daily were effective.
The usual dose for treating agitation due to schizophrenia or bipolar
disorder is 10 mg administered by intramuscular injection. Additional 10 mg
doses may be administered, but the efficacy of total daily 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 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 also may reduce blood levels of olanzapine are omeprazole
(Prilosec) and rifampin. Smoking may also 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, and the dose of olanzapine may need to be
reduced. Olanzapine can cause orthostatic hypotension, a drop in blood pressure
upon rising 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.
NURSING MOTHERS: Olanzapine is excreted into breast milk. Therefore,
it is recommended that olanzapine not be used by nursing mothers.
SIDE EFFECTS: Side effects seen with olanzapine include akathisia (an
inability to sit still), constipation, dizziness, drowsiness, insomnia, dry
mouth, orthostatic hypotension (see DRUG INTERACTIONS), 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 increased 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
Reference: FDA Prescribing Information
Last Editorial Review: 1/23/2006
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
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