olanzapine

(oh lan' za peen)

Zyprexa, Zyprexa IntraMuscular, Zyprexa Zydis

Pregnancy Category C

Drug classes

Antipsychotic

Dopaminergic blocking agent

Therapeutic actions

Mechanism of action not fully understood; blocks dopamine receptors in the brain, depresses the RAS; blocks serotonin receptor sites; anticholinergic, antihistaminic (H₁), and alpha-adrenergic blocking activity may contribute to some of its therapeutic (and adverse) actions; produces fewer extrapyramidal effects than most antipsychotics.

Indications

· Treatment of schizophrenia

· Treatment of acute manic episodes associated with bipolar 1 disorder and maintenance of bipolar 1 disorder as monotherapy, or combined with lithium or valproate

· Treatment of agitation associated with schizophrenia and bipolar 1 mania (injection)

· Unlabeled use: Dementia related to Alzheimer's disease

Contraindications and cautions

· Contraindicated with allergy to olanzapine, myeloproliferative disorders, severe CNS depression, comatose states, lactation.

· Use cautiously in elderly or debilitated patients, or with CV or cerebrovascular disease, dehydration, seizure disorders, Alzheimer's disease, prostate enlargement, narrow-angle glaucoma, history of paralytic ileus or breast cancer, pregnancy.

Available forms

Tablets—2.5, 5, 7.5, 10, 15, 20 mg; orally disintegrating tablets—5, 10, 15, 20 mg; powder for injection—10 mg

Dosages

ADULTS

· Schizophrenia: Initially, 5–10 mg PO daily, increase to 10 mg PO daily within several days; may be increased by 5 mg/day at 1-wk intervals to achieve desired effect. Do not exceed 20 mg/day.

· Bipolar mania: 10–15 mg/day PO; adjust at 5-mg intervals as needed, not less than q 24 hr. Maximum dose, 20 mg/day. For maintenance, 5–20 mg/day PO. The initial dose is 10 mg of olanzapine when combined with lithium or valproate.

· Agitation: 10 mg IM; range 5–10 mg IM; dose may be repeated in 2 hr if needed, safety of > 30 mg/24 hr not established.

PEDIATRIC PATIENTS

Safety and efficacy not established in patients < 18 yr.

DEBILITATED PATIENTS

Start with initial dose of 5 mg; 2.5 mg IM. Geriatric patients: 5 mg IM.

Pharmacokinetics

Route	Onset	Peak	Duration
Oral	Varies	6 hr	Weeks
IM	Rapid	15–45 min	Weeks

Metabolism: Hepatic; T_1/2: 30 hr

Distribution: Crosses placenta; enters breast milk

Excretion: Urine and feces

Adverse effects

· CNS: Somnolence, dizziness, nervousness, headache, akathisia, personality disorders, tardive dyskinesia, neuroleptic malignant syndrome

· CV: Orthostatic hypotension, peripheral edema, tachycardia

· GI: Constipation, abdominal pain

· Respiratory: Cough, pharyngitis

· Other: Fever, weight gain, joint pain, development of diabetes mellitus

Interactions

Drug-drug

· Increased risk of orthostatic hypotension with antihypertensives, alcohol, benzodiazepines; avoid use of alcohol and use caution with antihypertensives

· Increased risk of seizures with anticholinergics, CNS drugs

· May decrease effectiveness of levodopa, dopamine agonists

· Decreased effectiveness with rifampin, omeprazole, carbamazepine, smoking

· Increased risk of toxicity with fluvoxamine

Nursing considerations

CLINICAL ALERT!

Name confusion has occurred between Zyprexa (olanzapine) and Zyrtec (cetirizine); use caution.

Assessment

· History: Allergy to olanzapine, myeloproliferative disorders, severe CNS depression, comatose states, history of seizure disorders, lactation; CV or cerebrovascular disease, dehydration, Alzheimer's disease, prostate enlargement, narrow-angle glaucoma, history of paralytic ileus or breast cancer, elderly or debilitated patients, pregnancy

· Physical: T, weight; reflexes, orientation, IOP, ophthalmologic examination; P, BP, orthostatic BP, ECG; R, adventitious sounds; bowel sounds, normal output, liver evaluation; prostate palpation, normal urine output; CBC, urinalysis, liver and renal function tests

Interventions

· Do not dispense more than 1-wk supply at a time.

· Peel back foil on blister pack of disintegrating tablets; do not push through foil; use dry hands to remove tablet and place in mouth.

· Prepare solution for IM injection using 2.1 mL sterile water for injection. Resulting solution contains 5 mg/mL. Solution should be clear yellow. Use within 1 hr of reconstitution. Discard any unused portion.

· Monitor for the many possible drug interactions before beginning therapy.

· WARNING: Monitor elderly patients for dehydration and institute remedial measures promptly; sedation and decreased sensation of thirst related to CNS effects of drug can lead to dehydration.

· Encourage patient to void before taking the drug to help decrease anticholinergic effects of urinary retention.

· Monitor for elevations of temperature and differentiate between infection and neuroleptic malignant syndrome.

· Monitor for orthostatic hypotension and provide appropriate safety measures as needed.

Teaching points

· Take this drug exactly as prescribed; do not change dose without consulting your physician.

· Peel back foil on blister pack of disintegrating tablets; do not push through foil; use dry hands to remove tablet, place entire tablet in mouth.

· This drug cannot be taken during pregnancy. If you think you are pregnant or wish to become pregnant, contact your health care provider.

· You may experience these side effects: Drowsiness, dizziness, sedation, seizures (avoid driving, operating machinery, or performing tasks that require concentration); dizziness, faintness on arising (change positions slowly, use caution); increased salivation (if bothersome, contact your health care provider); constipation (consult with your health care provider for appropriate relief measures); fast heart rate (rest and take your time if this occurs).

· Report lethargy, weakness, fever, sore throat, malaise, mouth ulcers, and flulike symptoms.

Adverse effects in Italic are most common; those in Bold are life-threatening.