Long-Acting Risperidone Formulation
Yes, long-acting injectable risperidone is available as an FDA-approved extended-release injectable suspension for the treatment of schizophrenia. 1
Formulation Details
Risperidone for Extended-Release Injectable Suspension is an intramuscular depot formulation that uses microsphere technology to deliver sustained drug release over several weeks. 1
Available Dosage Strengths
- 12.5 mg per vial
- 25 mg per vial
- 37.5 mg per vial
- 50 mg per vial 1
Pharmacokinetic Profile
The long-acting formulation has a unique release pattern that differs substantially from oral risperidone:
- Initial release: Less than 1% of the dose is released immediately after injection 1
- Lag phase: 3-week period with minimal drug release 1
- Main release: Begins at week 3, maintained from weeks 4-6, and subsides by week 7 1
- Steady state: Achieved after approximately 4 injections (6-8 weeks of treatment) 2, 3
Administration Requirements
Oral supplementation is mandatory for the first 3 weeks after the initial injection due to the lag time before therapeutic levels are achieved. 2 The recommended starting dose for most patients is 25 mg every 2 weeks, with dose increases possible every 8 weeks up to a maximum of 50 mg every 2 weeks. 2
Clinical Guideline Support
Multiple major psychiatric organizations explicitly recognize risperidone as available in long-acting injectable form:
American Psychiatric Association (2004): Recommends considering "the oral form of the same medication (e.g. fluphenazine, haloperidol and risperidone)" when initiating LAI treatment, confirming risperidone LAI availability. 4
Second-generation LAI preference: Current guidelines favor second-generation LAIs like risperidone over first-generation agents due to better tolerability and fewer neurological side effects. 5, 6
Clinical Positioning
Long-acting risperidone represents a paradigm shift in schizophrenia management, as it was the first atypical antipsychotic available in depot formulation. 2, 3, 7 This combines the therapeutic advantages of atypical antipsychotics with assured medication delivery. 2
Primary Indications for Use
- Patients with recurrent relapses related to non-adherence 4
- Patients with history of frequent relapse on oral medication 4
- First-line maintenance treatment after first episode of schizophrenia (per modern guidelines) 6
- Patient preference for convenience 4
Safety Profile
The long-acting formulation demonstrates similar tolerability to oral risperidone:
- Extrapyramidal symptoms: Uncommon, dose-related, and comparable to oral formulation 2
- Weight gain: Small, dose-related increase similar to oral risperidone 2
- Injection site pain: Uncommon and decreases with continued administration 2
- Adverse event rate: Only 5.7% in a large observational study of 1232 patients 8