Conversion from Adderall IR 10 mg BID to Adderall XR
Convert Adderall IR 10 mg twice daily to Adderall XR 20 mg once daily in the morning. This provides equivalent total daily dosing with the same bioavailability profile.
Dosing Rationale
The conversion is straightforward and based on total daily dose equivalence:
- Current regimen: Adderall IR 10 mg × 2 doses = 20 mg total daily dose
- Target regimen: Adderall XR 20 mg once daily
Adderall XR 20 mg is bioequivalent to Adderall IR 10 mg twice daily 1, 2. The extended-release formulation contains immediate-release beads that deliver half the dose immediately upon ingestion, with delayed-release beads releasing the remaining half approximately 4 hours later 3. This dual-release mechanism mimics the twice-daily immediate-release dosing pattern while providing 12-hour symptom coverage 3, 4.
Key Pharmacokinetic Considerations
The bioavailability studies demonstrate that:
- Time to maximum concentration (Tmax) for Adderall XR is extended by approximately 3 hours compared to immediate-release formulations 4
- The 3:1 ratio of d-amphetamine to l-amphetamine remains identical between formulations 2, 3
- Onset of action occurs within 1.5 hours with extended coverage lasting 12 hours 3
Administration Guidelines
According to FDA labeling 1:
- Administer once daily in the morning after awakening
- The capsule may be swallowed whole or opened and sprinkled on applesauce (bioequivalent to intact capsule in fasted or fed states) 2
- Avoid late evening doses to prevent insomnia 1
Monitoring During Conversion
Following established stimulant guidelines 5:
- Assess blood pressure and pulse at conversion and regularly thereafter
- Monitor for appetite suppression, sleep disturbances, and mood changes within the first week
- Evaluate symptom control using standardized rating scales from parents/teachers after 1-2 weeks
- Check height and weight at follow-up visits
Important Caveats
Do not simply double the single dose when converting. The 20 mg XR formulation is specifically designed to replace 10 mg BID dosing through its biphasic release mechanism. If the patient requires higher total daily doses (e.g., currently taking 15 mg BID), convert to the equivalent XR dose (30 mg XR) 5.
The maximum recommended total daily dose remains 40 mg for amphetamines per FDA guidelines, though clinical practice occasionally exceeds this with careful documentation 5, 1.