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Brands and Forms

  • Zyprexa
    • Tablet: 2.5mg, 5mg, 7.5mg, 10mg, 15mg, 20mg
    • Powder for intramuscular injection: 5mg/ml (each vial contains 10mg)
  • Zyprexa Zydis
    • orally disintegrating tablet: 5mg, 10mg, 15mg, 20mg
  • Symbyax
    • An Olanzapine-Fluoxetine combination
    • Capsule (mg Olanzapine/mg Fluoxetine): 6mg/25mg, 6mg/50mg, 12mg/25mg, 12mg/50mg.
  • Zalasta
  • Zolafren
  • Olzapin
  • Rexapin

Uses of Olanzapine

Olanzapine is used in the treatment of Psychotic Disorders, Bipolar Disorder, Depressive Disorders, PTSD, OCD, and Borderline Personality Disorder.

Olanzapine can also be used in the management of behavioral disturbances, such as agitation and impulsivity, that can occur in various conditions like Impulse-Control Disorders and Disruptive Behavior Disorders.

How Olanzapine Works

Olanzapine is an Atypical Antipsychotic. It is an antagonist at the dopamine D2 receptor and the serotonin 2a and 2c receptors, but also has interactions with a myriad of other receptors.

Cautions when Using Olanzapine

In elderly individuals with Dementia, use of Antipsychotics has been associated with increased rates of sudden death. It is unclear whether the antipsychotic use is a cause, or simply a marker, of deteriorating health in these individuals.

Weight gain and metabolic side-effects (elevated glucose, lipids and cholesterol) can be very pronounced side-effects of Olanzapine.

Use caution in people with clinically important prostatic hypertrophy, narrow angle-closure glaucoma, and paralytic ileus, given the anticholinergic properties of this medication.

Individuals with Parkinson disease or Lewy-Body Dementia may have increased sensitivity to Olanzapine, which may manifest as confusion, obtundation, severe extrapyramidal symptoms, and neuroleptic malignant syndrome.

Do not use the intramuscular form of Olanzapine if there is a known risk of narrow angle-closure glaucoma or an unstable cardiovascular condition.

Use caution in people at risk for seizures or aspiration pneumonia.

People using Olanzapine should become familiar with its effects before driving or operating heavy machinery.

Dosing of Olanzapine

The usual dose range of Olanzapine is 5-20mg/day, usually given once daily at bedtime, though twice daily is also acceptable, with the larger dose given at bedtime. For mild conditions, or in individuals who are frail or elderly, a dose of 2.5mg/day may be appropriate. In rare cases, doses of up to 30mg/day are used.

The initial dose is usually 5mg/day, though in cases where there are very prominent symptoms of Mania, Psychosis or agitation, initial doses of 10mg or even 15mg can be used.

For the intramuscular form, the recommended initial dose is 10mg, and a second injection of 5-10mg can be given 2 hours later. The maximum daily dose should not exceed 20mg/day, with no more than 3 injections per 24 hours.

When wanting to stop Olanzapine, the dose should be decreased gradually over a period of 6-8 weeks.

Onset of action

Symptoms of Mania and Psychosis can improve within 1 week of use, but full therapeutic effect may take several weeks. If there is no significant effect after 4-6 weeks, including a couple of weeks at doses above 10mg/day, then it may not work at all.

Acute agitation can improve after a single dose.

For other conditions, 4-6 weeks may be needed to see a therapeutic effect.

Kidney impairment

No dose adjustment necessary, though for the intramuscular form consider using an initial dose of 5mg.

Liver impairment

No dose adjustment necessary, though for the intramuscular form consider using an initial dose of 5mg.

Side-effects of Olanzapine

Below is a list of most of the reported side-effects of Olanzapine. Most of these side-effects occur in only a minority of individuals, and many also resolve with time while the medication is continued.

Cardiovascular: postural hypotension; tachycardia; elevated or lowered blood pressure; deep venous thrombosis (rare); pulmonary edema (rare).

Central Nervous System: somnolence; dizziness; extrapyramidal symptoms; weakness; insomnia; tremor; abnormal gait; abnormal dreams; memory difficulties; loss of libido; paresthesia; seizures (rare).

Dermatologic: bruising; excessive perspiration.

Endocrine/Metabolic: Weight gain; metabolic syndrome (insulin resistance, elevated blood sugars, hyperlipidemia and hypercholesterolemia); elevated prolactin; breast pain, enlargement, or milk production in men and women; trouble conceiving; hyperthermia.

Eyes, Ears, Nose and Throat: rhinitis; pharyngitis; amblyopia; conjunctivitis.

Gastrointestinal: dry mouth; constipation; dyspepsia; nausea; increased appetite; vomiting; flatulence; increased salivation; increased thirst; hepatitis (rare); pancreatitis (rare).

Genitourinary: urinary incontinence; urinary tract infection; vaginitis; priapism; erectile dysfunction.

Hematologic: neutropenia (rare).

Musculoskeletal: muscle stiffness; muscle pains; muscle spasms; neuroleptic malignant syndrome (rare).

Psychiatric: emotional lability; obsessive-compulsive symptoms; psychosis (rare); mania (rare).

Respiratory: cough; shortness of breath; aspiration pneumonia (due to esophageal dysmotility; rare).

Common side-effects of Olanzapine

Somnolence, weight gain, metabolic syndrome (elevated blood sugars, lipids and cholesterol), dizziness, extrapyramidal symptoms (akathesia being the most common), dry mouth, constipation, dyspepsia, nausea.

Rare but serious side-effects of note of Olanzapine

Olanzapine overdose

Agitation, delirium, drowsiness, dysarthria, hypertension, hypotension, neuroleptic malignant syndrome, reduced level of consciousness, slurred speech, tachycardia, extrapyramidal symptoms, aspiration, cardiac arrhythmias (eg. supraventricular tachycardia), cardiopulmonary arrest, convulsions, respiratory depression, coma. Can be fatal.

Olanzapine and pregnancy

Category C: some animal studies show adverse effects at very high doses, but no controlled human studies have been done; should only be used in pregnancy if clearly needed and if benefits outweigh potential risks.

Olanzapine, weight gain and metabolic syndrome

Up to 30% of people taking Olanzapine will gain about 7% of their total body weight within 8 weeks of starting the medication [ref, ref]. Metabolic side-effects, including elevated glucose and lipids can also occur, which in the long-term increase the risk for heart disease and vascular problem.

See here for further information on these side-effects, and how they can be managed.

Medical Monitoring for Olanzapine

Monitoring for weight gain and a metabolic syndrome requires the following measures to be taken prior to starting the medication, then monthly for the first 3 months of use, and then every 3 months:

  • Body Mass Index (BMI)
  • waistline circumference at umbilicus
  • blood pressure
  • fasting blood glucose
  • fasting blood lipids and cholesterol

To monitor for elevated prolactin, prolactin levels should be measured prior to starting the medication, and then one month after every dose increase.

Liver function tests should also be measured prior to starting the medication and then once or twice a year.

Drug Interactions with Olanzapine

  • Avoid using the intramuscular form of Olanzapine within one hour of administering a parenteral benzodiazepine.
  • Olanzapine blood concentrations can be reduced by Carbamazepine, Omeprazole, Rifampin, Ritonavir, and cigarette smoke.
  • Olanzapine blood concentrations can be increased by Fluvoxamine.
  • Olanzapine may enhance the effects of antihypertensive medications and other sedative medications.