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olanzapine pamoate

Last reviewed 2025-12-30

Reviewed by PsychMed Editorial Team.

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Long-acting injectable antipsychoticLAI available

Brands: ZYPREXA RELPREVV

Sources updated 2025 • 4 references

Quick summary

General Information

Olanzapine pamoate (Zyprexa Relprevv) is a long-acting injectable formulation of olanzapine indicated for schizophrenia.

It is clinically “olanzapine-like” in efficacy and metabolic burden, but it has a unique safety workflow: PDSS risk requires a structured observation period after every injection per label.

Compared with many depots, olanzapine pamoate is often reserved for situations where olanzapine’s clinical effect is clearly favored and the team can support required observation, transportation, and reliable follow-up.

The observation requirement and metabolic burden frequently dominate selection decisions more than pharmacologic differences versus other LAIs.

U.S. approvals

  • Schizophrenia ()

Formulations & strengths

  • Deep intramuscular injection every 2–4 weeks (dose/interval per label).

Generic availability

  • Long-acting injectable remains brand-only in the United States as of 2025.

Olanzapine pamoate use is comparatively limited because the post-injection observation requirement adds staffing and facility complexity, and because olanzapine’s high metabolic burden constrains long-term use in some patients. When selected, injection visits can be leveraged for structured metabolic monitoring and relapse-prevention check-ins.

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Mechanism of Action

Refer to the Glossary entry on Neurotransmitters for background on receptor systems involved in serious mental illness.

Olanzapine is a serotonin 5-HT2A and dopamine D2 antagonist with strong histamine H1 and muscarinic activity.

Antipsychotic effect is generally attributed to sustained D2 receptor occupancy with serotonergic modulation; sedation and anticholinergic effects reflect H1 and muscarinic activity.

  • Dopamine D2 receptor antagonism.
  • Serotonin 5-HT2A receptor antagonism.
  • Histamine H1 antagonism contributing to sedation and weight gain.
  • Muscarinic antagonism contributing to anticholinergic effects.

Metabolism and Pharmacokinetics

  • Olanzapine pamoate releases olanzapine over weeks; the effective half-life after LAI administration is on the order of weeks, and clinical effects can persist for months after discontinuation.
  • Olanzapine is metabolized primarily via CYP1A2 (and minor 2D6). Smoking induces 1A2 and increases clearance; smoking cessation can increase exposure and sedation risk.
  • Depot washout is slow; dose changes and missed injections have delayed clinical effects compared with daily oral dosing.

Dosing and Administration

  • Administration is deep intramuscular injection (commonly gluteal). Dose and interval (q2–4 weeks) are individualized to symptom control and tolerability within labeled schedules.
  • A structured post-injection observation period is required after every injection due to PDSS risk; clinics often embed this into workflow with monitoring checklists and clear discharge criteria.
  • Missed-dose management is time-dependent; many teams document a missed injection plan at initiation because delayed dosing can result in prolonged low exposure.

Monitoring & Labs

  • Post-injection observation per label after every dose; monitor for sedation, delirium symptoms, and impaired coordination.
  • Weight/BMI and waist circumference; fasting lipids and glucose/HbA1c at baseline and periodically.
  • Blood pressure/orthostasis monitoring in older adults or antihypertensive co-use.
  • Bowel function and anticholinergic burden (constipation risk).
  • Movement disorder monitoring (parkinsonism, tardive dyskinesia) as clinically indicated.

Adverse Effects

FDA boxed warnings

  • Increased mortality in elderly patients with dementia-related psychosis (antipsychotic class warning).
  • Post-injection delirium/sedation syndrome (PDSS): requires post-injection observation after every dose per label.

Common side effects (≥10%)

  • Weight gain and metabolic change: High metabolic burden similar to oral olanzapine. Monitor weight/BMI, lipids, and glucose/HbA1c per routine antipsychotic practice and provide structured lifestyle counseling.
  • Sedation: Sedation is common and can be clinically significant, particularly in older adults or when combined with other sedatives. Consider falls risk and functional impairment in monitoring plans.
  • Anticholinergic effects: Dry mouth and constipation are common; assess bowel function and hydration, especially when other anticholinergics are co-prescribed.
  • Orthostatic hypotension: Alpha-adrenergic effects can contribute to dizziness or orthostasis, especially early in treatment or when combined with antihypertensives.
  • Injection-site reactions: Local pain may occur; use proper technique and document site selection to support tolerability.

Other notable effects

  • PDSS is rare but safety-critical; protocols focus on monitoring for sedation, delirium, and impaired coordination after each injection.
  • Class risks include NMS and tardive dyskinesia; maintain vigilance in high-risk patients.

Interactions

  • Smoking induces CYP1A2 and can lower olanzapine exposure; smoking cessation can increase exposure and sedation risk.
  • Strong CYP1A2 inhibitors (e.g., fluvoxamine, ciprofloxacin) increase exposure; dose reduction and close monitoring for sedation/orthostasis are common.
  • Additive CNS depression with alcohol, benzodiazepines, opioids, or sedative hypnotics; this interaction is especially relevant given the post-injection observation requirement.

Other Useful Information

  • Selection is often driven by logistics: clinic capacity for required observation, reliable transport, and a clear shared plan for what to do if an injection is late.
  • Injection visits can be leveraged for structured metabolic monitoring and relapse-prevention check-ins.
  • Changes in smoking status should be explicitly documented because of CYP1A2 effects on olanzapine exposure.

References

  1. Zyprexa Relprevv (olanzapine Pamoate) Extended Release Injectable Suspension — Prescribing Information — DailyMed (2025)
  2. Post Injection Delirium/sedation Syndrome IN Patients Treated With Olanzapine Pamoate: Mechanism, Incidence, AND Management — CNS Drugs (2015)
  3. The American Psychiatric Association Practice Guideline for the Treatment of Patients With Schizophrenia — American Psychiatric Association (2020)
  4. ZYPREXA (olanzapine) label — DailyMed (2025)
olanzapine pamoate (ZYPREXA RELPREVV) — PsychMed