Available Atypical Antipsychotic Long-Acting Injectable Formulations
The atypical antipsychotics currently available as long-acting injectable (LAI) formulations are risperidone, paliperidone, aripiprazole, and olanzapine 1, 2, 3.
Currently Available Second-Generation LAI Antipsychotics
The evidence clearly identifies four atypical (second-generation) antipsychotics with LAI formulations:
Risperidone
- Available as intramuscular microsphere formulation (Risperdal Consta)
- Also available as subcutaneous formulation (Perseris)
- Multiple formulations exist with varying administration intervals 4
Paliperidone Palmitate
- Available as aqueous nanocrystal suspension
- Administered intramuscularly
- The active metabolite of risperidone 5
Aripiprazole
- Available in two distinct formulations:
- Aripiprazole monohydrate (Abilify Maintena)
- Aripiprazole lauroxil (Aristada)
- Both administered intramuscularly 2
Olanzapine Pamoate
- Microcrystalline salt formulation suspended in aqueous solution
- Administered intramuscularly
- Requires post-injection observation due to risk of post-injection delirium/sedation syndrome 5
Clinical Context from Guidelines
The 2009 British Journal of Psychiatry guidelines noted that risperidone was the first available second-generation LAI, with olanzapine and paliperidone formulations becoming available subsequently 6. The 2020 APA guidelines recommend LAI antipsychotics for patients who prefer such treatment or have a history of poor or uncertain adherence 7.
Important Distinguishing Features
These formulations differ substantially in their practical characteristics 1, 3:
- Route of administration: Intramuscular vs. subcutaneous options
- Injection frequency: Ranging from every 2 weeks to every 3 months depending on formulation
- Needle gauge and injection volume: Varies by product
- Oral supplementation requirements: Some require initial oral overlap
- Post-injection observation: Only olanzapine pamoate requires extended monitoring
- Storage requirements: Refrigeration needs differ by product
Note: While the 2009 guideline is older, it accurately identifies the available agents, which has been confirmed by more recent research from 2021-2025 1, 2, 4, 8. No additional atypical antipsychotic LAI formulations beyond these four medications have been FDA-approved since then, though various delivery systems and formulations of these same drugs continue to be developed.