What is the starting dose of Olanzapine (atypical antipsychotic) for adults?

Starting Dose of Olanzapine for Adults

The recommended starting dose of oral olanzapine for adults is 5-10 mg once daily, with most patients beginning at 5 mg and titrating to a target dose of 10 mg/day within several days. 1

Standard Oral Dosing

• Begin with 5-10 mg orally once daily without regard to meals, with a target dose of 10 mg/day reached within several days for schizophrenia 1
• The FDA-approved dosing demonstrates efficacy in the 10-15 mg/day range, though doses above 10 mg/day were not more efficacious than 10 mg/day in clinical trials 1
• Maximum recommended dose is 20 mg/day; olanzapine is not indicated for doses above this threshold 1
• Dose adjustments should occur at intervals of at least 1 week, as steady-state concentrations require approximately one week to achieve 1

Lower Starting Doses for Specific Populations

Start at 2.5-5 mg in patients with risk factors for slower metabolism or increased sensitivity: 2, 1

• Geriatric patients (≥65 years) 1
• Debilitated patients 1
• Patients predisposed to hypotensive reactions 1
• Nonsmoking female patients ≥65 years (combination of factors resulting in slower metabolism) 1
• Hepatic impairment - reduced starting dose of 2.5 mg is recommended 2
• Alzheimer's disease patients - 2.5 mg starting dose 2

Intramuscular Dosing for Acute Agitation

• Standard IM dose: 10 mg for acute agitation associated with schizophrenia or bipolar mania 1
• Alternative doses of 2.5 mg, 5 mg, or 7.5 mg IM can be used based on clinical factors 3
• Geriatric patients: 5 mg IM should be considered 1
• Debilitated or sensitive patients: 2.5 mg IM 1
• Clinical trials demonstrated efficacy with IM doses ranging from 2.5-10 mg 3

Important Clinical Considerations

• Monitor for orthostatic hypotension, particularly with IM administration - assess patients before subsequent doses 2, 1
• Avoid combining with benzodiazepines when possible due to risk of oversedation, respiratory depression, and reported fatalities with high-dose olanzapine 2
• Common side effects include drowsiness, sedation, weight gain (approximately 40% of patients), dry mouth, and dizziness 2, 4
• Weight gain is more likely with higher starting doses and in underweight patients at baseline 4

Route-Specific Administration

• Oral administration (tablets or orally disintegrating tablets) is the primary route 2
• IM olanzapine should be injected slowly, deep into muscle mass - never administer IV or subcutaneously 1
• When transitioning from IM to oral, begin oral dosing at 5-20 mg/day as soon as clinically appropriate 1