What is the equivalent dosing of Dexedrin (Dextroamphetamine) IR for a patient converting from Adderall (Amphetamine) 30 mg Immediate Release (IR) twice a day (BID)?

Adderall to Dexedrine IR Conversion

Convert Adderall 30 mg IR BID (total daily dose 60 mg) to approximately Dexedrine 20 mg IR BID (total daily dose 40 mg), which represents a 2:3 ratio reduction based on the higher dextroamphetamine content in pure Dexedrine formulations.

Pharmacologic Basis for Conversion

Adderall contains a 3:1 ratio of dextroamphetamine to levoamphetamine salts, meaning approximately 75% of the amphetamine content is the more potent dextroamphetamine isomer 1. Dexedrine (dextroamphetamine) is 100% the active d-isomer, making it more potent milligram-per-milligram 1.

Recommended Conversion Strategy

Starting dose: Begin with Dexedrine 20 mg IR BID (total 40 mg daily) 1.

Rationale for this conversion:

• The patient's current total daily amphetamine dose is 60 mg of mixed amphetamine salts 2
• This exceeds the recommended maximum total daily dose of 40 mg for amphetamines 2
• Converting to pure dextroamphetamine at 40 mg daily provides comparable therapeutic effect while adhering to guideline-recommended maximum dosing 1, 2
• The 2:3 ratio (40 mg Dexedrine for 60 mg Adderall) accounts for the increased potency of pure dextroamphetamine 1

Titration and Monitoring Protocol

Initial monitoring schedule:

• Assess symptom control and side effects within 1 week of conversion 1
• If inadequate response, increase by 2.5-5 mg increments per dose weekly 1
• Maximum recommended total daily dose should not exceed 40 mg 2

Key monitoring parameters:

• Blood pressure and pulse at each visit (especially critical given the high baseline dose) 1
• Weight monitoring at each visit to assess appetite suppression 1, 2
• Systematic assessment of insomnia, anorexia, headaches, agitation, and cardiovascular symptoms 1, 2

Critical Safety Considerations

This patient is at the upper limit of recommended dosing. The American Academy of Child and Adolescent Psychiatry explicitly states that maximum total daily doses are 40 mg for amphetamines, and clinical consensus limits the upper range to 40 mg total daily 2. The current Adderall dose of 60 mg daily exceeds these recommendations 2.

Important caveat: If symptom control is not achieved at the maximum recommended 40 mg daily dose of Dexedrine, "more is not necessarily better" 2. Consider:

• Switching to an alternative stimulant (methylphenidate) 1
• Adding environmental or psychosocial interventions 2
• Evaluating for non-stimulant medication options 2

Dosing Schedule

Recommended timing:

• First dose: After breakfast (e.g., 20 mg)
• Second dose: Around noon/after lunch (e.g., 20 mg) 1
• Optional third dose: After school/late afternoon if needed for homework or evening activities, using lower doses (e.g., 5-10 mg) to avoid sleep disruption 1

Duration of action consideration: Dexedrine IR typically provides 4-6 hours of coverage per dose, similar to Adderall IR 1. The patient may require the same BID dosing schedule, though some patients on dextroamphetamine may achieve adequate coverage with once-daily dosing if higher morning doses are used 1.

Common Pitfalls to Avoid

• Do not perform a 1:1 conversion - this would result in excessive dosing given the higher potency of pure dextroamphetamine 1
• Monitor for increased side effects - dextroamphetamine has greater effects on appetite and sleep compared to mixed amphetamine salts due to longer excretion half-life 1
• Document medical necessity if doses approach or exceed 40 mg daily, including that lower doses were inadequate and higher doses produce no problematic side effects 1
• Assess for tolerance at higher doses, which may indicate need for medication holiday or alternative treatment 1