Oral Aripiprazole Equivalent for 300mg Depot
For a patient receiving aripiprazole depot 300mg monthly, the oral equivalent is 10-15 mg daily, as depot formulations are designed to provide sustained therapeutic levels comparable to standard oral maintenance dosing. 1
Understanding Depot-to-Oral Conversion
The relationship between depot and oral aripiprazole is not a simple 1:1 conversion based on total monthly dose. Instead, depot formulations are engineered to maintain steady-state plasma concentrations equivalent to daily oral dosing:
- Aripiprazole depot 300mg monthly provides plasma concentrations comparable to oral aripiprazole 10-15 mg daily 1
- The depot formulation achieves steady-state levels similar to those observed with daily oral administration, not cumulative monthly dosing 2
- Aripiprazole has a long elimination half-life (approximately 75 hours for the parent compound and 94 hours for the active metabolite), which facilitates once-monthly depot administration 3
Clinical Context for Depot Dosing
The standard depot dosing regimen includes:
- 400mg depot monthly is the typical maintenance dose (with 300mg as an alternative lower dose) 2
- When initiating depot therapy, patients typically receive oral aripiprazole 10-20 mg daily for 14 days concomitantly to bridge to steady-state depot levels 2
- The 300mg depot dose represents a lower maintenance option for patients who may require less intensive dosing 4
Practical Conversion Guidance
If converting from 300mg depot back to oral therapy, initiate oral aripiprazole 10-15 mg daily 1, 3:
- Start oral dosing on the day the next depot injection would have been due
- The recommended oral starting dosage is 10 or 15 mg daily 3
- Monitor for symptom stability over the first 2-4 weeks after conversion
- Plasma concentrations with depot formulations mirror those achieved with standard daily oral dosing 2
Important Caveats
Drug interactions significantly affect aripiprazole levels: Aripiprazole is metabolized by CYP3A4 and CYP2D6, so strong inhibitors or inducers of these enzymes may require dose adjustments 3, 4. In one case report, a patient required depot doses up to 400mg (double the standard recommendation) due to concomitant CYP3A4 inducers 4.
The depot formulation does not represent 300mg of "active drug" distributed over a month—rather, it provides controlled release to maintain therapeutic plasma levels equivalent to 10-15 mg oral daily 1, 2.