How do I convert a 2.5 mg oral olanzapine dose to an intramuscular (IM) dose, and what are the maximum daily limits and monitoring recommendations?

Olanzapine Oral to IM Conversion for 2.5 mg Dose

For a 2.5 mg oral olanzapine dose, administer 2.5 mg intramuscularly when converting to the IM formulation, as there is no dose adjustment required between oral and IM routes for olanzapine. 1

Dosing Guidelines for IM Olanzapine

The FDA-approved IM olanzapine dosing for agitation is 2.5 mg to 10 mg per injection, with 2.5 mg specifically recommended for patients who are debilitated, predisposed to hypotensive reactions, or more pharmacodynamically sensitive to olanzapine. 1

• The standard recommended dose for agitation in schizophrenia and bipolar mania is 10 mg IM, but lower doses of 2.5 mg, 5 mg, or 7.5 mg may be considered when clinical factors warrant 1
• A 2.5 mg IM dose is appropriate for geriatric patients, debilitated patients, or those at risk for hypotension 1

Maximum Daily Limits and Dosing Intervals

The maximum total daily dose is 30 mg, with specific timing restrictions: subsequent injections should be given no more frequently than 2 hours after the initial dose and 4 hours after the second dose. 1

• If agitation persists after the initial dose, subsequent doses up to 10 mg may be given 1
• Maximal dosing (three 10 mg doses administered 2-4 hours apart) is associated with substantial orthostatic hypotension 1
• The efficacy of repeated IM doses has not been systematically evaluated in controlled trials 1

Critical Monitoring Requirements

Assess for orthostatic hypotension prior to administering any subsequent IM doses; do not administer additional doses to patients with clinically significant postural changes in systolic blood pressure. 1

• IM olanzapine may cause transient reductions in blood pressure and heart rate 2
• Monitor for somnolence, dizziness, and anticholinergic effects (dry mouth, constipation) 3
• Patients should be observed for cardiovascular effects, particularly with repeated dosing 2

Administration Technique

Inject slowly, deep into the muscle mass; IM olanzapine is intended for intramuscular use only and must not be administered intravenously or subcutaneously. 1

• Reconstitute with 2.1 mL of Sterile Water for Injection to provide approximately 5 mg/mL concentration 1
• For a 2.5 mg dose, withdraw 0.5 mL of the reconstituted solution 1
• Use immediately within 1 hour after reconstitution; discard any unused portion 1

Important Contraindications and Incompatibilities

Do not combine IM olanzapine with diazepam injection (causes precipitation), do not use lorazepam injection for reconstitution (delays reconstitution), and do not combine with haloperidol injection (degrades olanzapine over time). 1

Transition to Oral Therapy

Once clinically appropriate, transition to oral olanzapine at 5-20 mg/day; IM therapy is intended for acute management only. 1

• The onset of action for IM olanzapine is faster than oral formulations, making it suitable for acute agitation 2
• IM olanzapine reaches therapeutic effect more rapidly than IM haloperidol or lorazepam 2