Yes, olanzapine is available as a long-acting injectable (LAI) formulation.
Olanzapine has an FDA-approved intramuscular long-acting injection formulation called olanzapine pamoate (OLAI), which is administered as a deep gluteal injection every 2-4 weeks depending on the dose. 1
Available LAI Formulations
Currently Marketed: Olanzapine Pamoate (Intramuscular)
- Dosing regimens: 150 mg, 210 mg, or 300 mg every 2 weeks; or 300 mg or 405 mg every 4 weeks 2
- Administration: Deep intramuscular gluteal injection using a 19-gauge needle 2
- Injection volume: 1 to 2.7 mL 2
- Pharmacokinetics: Half-life of 30 days with steady state reached at approximately 12 weeks 3
Newer Formulation in Development: TV-44749 (Subcutaneous)
A subcutaneous LAI formulation (TV-44749) recently demonstrated efficacy and safety in the phase 3 SOLARIS trial, designed specifically to avoid the risk of post-injection delirium/sedation syndrome (PDSS) 4
Critical Safety Consideration
The intramuscular olanzapine pamoate formulation carries a significant risk of post-injection delirium/sedation syndrome (PDSS), occurring at a rate of 0.07% per injection. 2, 3 This manifests as symptoms similar to oral olanzapine overdose, including:
- Sedation to coma
- Delirium
- Confusion
- Slurred speech
- Altered gait
- Weakness
Mandatory Risk Management
Due to PDSS risk, patients must be observed for 3 hours post-injection in a healthcare facility with ready access to emergency response services. 2 This requirement significantly impacts the practical use of this formulation compared to other LAIs.
Clinical Context
The 2009 guideline noted that olanzapine LAI was in development at that time 5, and it has since become commercially available. However, therapeutic drug monitoring studies suggest a therapeutic reference range of 20-40 ng/mL for both oral and LAI formulations 6, indicating similar efficacy profiles when appropriate blood levels are achieved.
The choice to use olanzapine LAI should weigh the benefits of improved adherence against the mandatory 3-hour post-injection observation requirement and PDSS risk, which may make other second-generation LAIs (such as paliperidone palmitate or aripiprazole LAI) more practical alternatives in many clinical situations.