Half-Life of Abilify Aristada
Aristada (aripiprazole lauroxil) has an extremely long half-life of approximately 53.9-57.2 days following the last injection, making it one of the longest-acting antipsychotic formulations available. 1
Pharmacokinetic Profile of Aristada
Aristada is a long-acting injectable formulation of aripiprazole with distinct pharmacokinetic properties:
- Elimination half-life: 53.9 days for the 1064 mg dose, 55.1 days for the 882 mg dose, and 57.2 days for the 441 mg dose 1
- Duration of absorption: Approximately 43 days (95% CI 42-45 days) 1
- Lag time before absorption: 3.2 days (95% CI 3.0-3.5 days) 1
- Total duration of input into systemic circulation: 46 days following intramuscular administration 1
This extended half-life is significantly longer than oral aripiprazole, which has a half-life of approximately 75 hours (about 3 days) 2.
Clinical Implications of Long Half-Life
The extended half-life of Aristada has several important clinical implications:
- Dosing intervals: Aristada can be administered at extended intervals (monthly, every 6 weeks, or every 8 weeks depending on dose) 1
- Steady state: Steady-state concentrations are achieved after approximately 14 days of dosing 2
- Full therapeutic effect: May take 1-4 weeks to reach full effect 2
- Reduced risk of discontinuation syndrome: The long half-life provides a gradual decrease in drug levels if a dose is missed 3
- Prolonged exposure after discontinuation: Drug effects will persist for several months after the last injection 1
Available Dosing Regimens
Based on pharmacokinetic studies, Aristada is available in multiple dosing regimens:
- 441 mg administered monthly (every 4 weeks)
- 662 mg administered monthly (every 4 weeks)
- 882 mg administered monthly (every 4 weeks) or every 6 weeks
- 1064 mg administered every 8 weeks (2 months) 1
Monitoring Considerations
The extended half-life requires special consideration for:
- Adverse effects: Any adverse effects may persist for weeks to months after discontinuation
- Drug interactions: Effects of drug interactions may be prolonged
- Pregnancy planning: The long half-life necessitates discontinuation well in advance of planned pregnancy 3
- Switching medications: Requires careful planning due to prolonged washout period
Caution in Special Populations
The long half-life of Aristada requires particular caution in:
- Elderly patients: May have reduced clearance leading to higher drug exposure
- Patients with hepatic impairment: Aripiprazole is metabolized by the liver
- Pediatric patients: Limited data available, but case reports suggest prolonged effects and potential for toxicity even with small doses 4
This extended half-life is a key characteristic that distinguishes Aristada from many other antipsychotic medications and must be considered when initiating or discontinuing treatment.