What is the equivalent dose of Adderall (amphetamine and dextroamphetamine) for a 45mg extended-release (ER) dose of methylphenidate?

Methylphenidate 45mg ER to Adderall Dose Conversion

Methylphenidate 45mg ER is approximately equivalent to 15-22.5mg of Adderall (amphetamine mixed salts), using a conversion ratio of roughly 2:1 to 3:1 (methylphenidate to amphetamine).

Conversion Rationale

The conversion between methylphenidate and amphetamine formulations is not straightforward because these are different medication classes with distinct pharmacokinetic and pharmacodynamic properties 1. However, clinical practice and research provide guidance:

Standard Conversion Approach

• Start with approximately 15mg of Adderall when converting from 45mg methylphenidate ER, representing a conservative 3:1 ratio 2, 3
• Research comparing these medications suggests that lower doses of Adderall (7.5-12.5mg twice daily) produced effects comparable to or greater than higher doses of Ritalin (10-17.5mg twice daily) 2
• In direct comparison studies, 12.5mg/day of Adderall was found to be functionally more potent than 25.2mg/day of methylphenidate 3

Titration Strategy

• Begin with Adderall 10mg once daily (if using extended-release formulation like Adderall XR) and titrate by 5mg weekly increments based on response 4
• The usual starting dose for Adderall XR is 10mg in the morning, with titration up to 50mg maximum 4
• Monitor response over 7 days at each dose level, as stimulant effects are seen rapidly and allow for efficient titration 4

Important Clinical Considerations

Duration of Action Differences

• Methylphenidate ER formulations vary significantly in duration: newer formulations like OROS-methylphenidate (Concerta) provide 12 hours of coverage, while standard ER formulations provide only 8 hours 5
• Adderall XR provides approximately 8-9 hours of coverage, which is shorter than OROS-methylphenidate but longer than standard methylphenidate ER 5
• This duration difference means the conversion is not purely dose-based but also depends on coverage needs throughout the day 5

Individual Response Variability

• More than 90% of patients respond to one of the stimulant classes (methylphenidate or amphetamine), but individual response is unpredictable 4
• A patient's response to methylphenidate does not reliably predict their response to amphetamines, necessitating careful titration 4
• Calculating dose based on mg/kg has not been helpful, as dose variations are not related to height or weight 4

Monitoring During Conversion

Essential Parameters to Track

• ADHD symptom control using standardized rating scales from both parents and teachers 4
• Adverse effects including decreased appetite, insomnia, irritability, and cardiovascular parameters (blood pressure, heart rate) 4
• Time course of symptom control throughout the day to ensure adequate coverage 2
• Rebound effects in late afternoon/evening, which may indicate need for dose adjustment 5

Common Pitfalls to Avoid

• Do not assume 1:1 conversion between methylphenidate and amphetamine formulations, as amphetamines are more potent on a milligram basis 2, 3
• Avoid starting at the mathematically "equivalent" dose without considering that Adderall may be functionally more potent, risking excessive side effects 2
• Do not neglect to account for formulation differences within each medication class (immediate-release vs. various extended-release technologies) 5, 1

Practical Implementation Algorithm

1. Start with Adderall XR 10mg once daily in the morning (conservative approach for safety) 4
2. Assess response after 7 days using parent and teacher rating scales 4
3. If inadequate response and no significant adverse effects, increase to 15mg daily 4
4. Continue weekly titration by 5mg increments up to maximum 50mg daily until optimal response achieved 4
5. If patient requires coverage beyond 8-9 hours, consider either adding a small afternoon immediate-release dose or switching back to OROS-methylphenidate for 12-hour coverage 5