Adults

For Schizophrenia: Initial dose is 10 mg once daily. For Bipolar I Disorder (Manic or Mixed Episodes): Initial dose is 10-15 mg once daily. Dosage adjustment should be based on clinical response and tolerability.

Elderly

A lower starting dose of 5 mg/day should be considered for elderly patients, particularly those with other risk factors for adverse reactions. Titrate carefully.

Renal_impairment

No specific dose adjustment is routinely required for renal impairment, but caution is advised. A lower starting dose may be considered in patients with severe renal impairment. Similarly for hepatic impairment, a lower starting dose of 5 mg/day should be considered.

Onset

Initial therapeutic effects for agitation may be seen within hours; however, full antipsychotic effects may take several days to weeks.

Excretion

Approximately 57% of the dose is excreted in urine, and 30% in feces, mainly as metabolites.

Half life

Mean elimination half-life is approximately 21-54 hours (average 33 hours).

Absorption

Rapidly and well absorbed after oral administration, reaching peak plasma concentrations within 5-8 hours. Food does not affect the rate or extent of absorption.

Metabolism

Extensively metabolized in the liver, primarily through direct glucuronidation and CYP1A2 mediated oxidation. Less contribution from CYP2D6.

Carbamazepine (a CYP1A2 inducer)

Decreased olanzapine plasma concentrations. A dose increase of olanzapine may be necessary.

Fluvoxamine (a CYP1A2 inhibitor)

Increased olanzapine plasma concentrations. A dose reduction of olanzapine may be necessary.

Alcohol and other CNS depressants

May cause additive sedative effects; concurrent use should be approached with caution.