What is the equivalent dose of Adderall XR (amphetamine and dextroamphetamine) to Vyvanse (lisdexamfetamine) 70mg in a patient with Attention Deficit Hyperactivity Disorder (ADHD)?

Converting Vyvanse 70mg to Adderall XR

Start Adderall XR at 10mg once daily in the morning and titrate by 5mg weekly increments based on response, as there is no established direct dose equivalency between lisdexamfetamine (Vyvanse) and mixed amphetamine salts (Adderall XR). 1, 2

Conversion Protocol

Initial Dosing Strategy

• Discontinue Vyvanse 70mg abruptly and start Adderall XR at 10mg once daily in the morning 2
• No washout period is required when switching between stimulant medications 2
• The 10mg starting dose is the standard initial dose for adults with ADHD, regardless of prior stimulant exposure 1

Why No Direct Conversion Exists

• Lisdexamfetamine is a prodrug that requires enzymatic hydrolysis (predominantly by red blood cells) to convert to active d-amphetamine, while Adderall XR contains a mixture of amphetamine salts (75% dextroamphetamine and 25% levoamphetamine) with immediate bioavailability 3, 4, 5
• The pharmacokinetic profiles differ substantially: Vyvanse provides up to 14 hours of coverage through its prodrug mechanism, while Adderall XR uses a two-stage delivery system for approximately 12 hours of action 3, 6
• These distinct mechanisms and formulations make direct dose equivalency calculations unreliable and potentially dangerous 2

Titration Algorithm

Weekly Dose Adjustments

• Increase by 5mg weekly increments until optimal symptom control is achieved 1, 2
• Maximum recommended daily dose is 50mg for adults 1, 2
• Allow at least one week between dose increases to properly evaluate therapeutic response and side effects 1

Systematic Assessment at Each Dose Level

• Use standardized ADHD rating scales to objectively measure symptom severity before each dose increase 1
• Evaluate both therapeutic effects (attention, focus, task completion) and side effects (appetite, sleep, mood, cardiovascular symptoms) 1
• More than 70% of patients respond when a full range of doses is properly titrated 1

Monitoring Requirements

Cardiovascular Monitoring

• Assess blood pressure and pulse at baseline and with each dose increase 1
• This is particularly important given the patient was on a high dose (70mg) of Vyvanse 1

Symptom and Side Effect Tracking

• Schedule follow-up appointments at least monthly until symptoms are stabilized 1
• Monitor for common adverse events including decreased appetite, insomnia, headache, irritability, and weight loss 4, 7
• Administer medication in the morning to minimize sleep disturbances 1, 2

Critical Pitfalls to Avoid

Dosing Errors

• Never attempt a 1:1 conversion or assume equivalent dosing between Vyvanse 70mg and Adderall XR - this could result in either underdosing or dangerous overstimulation 2
• Do not start at too high a dose, which can lead to unnecessary side effects and decreased medication adherence 1
• Avoid the assumption that "more is better" - some patients experience paradoxical worsening of focus at higher doses due to overstimulation 1

Inadequate Assessment

• Do not increase doses without allowing sufficient time (at least one week) to evaluate response 1
• Failure to systematically assess both benefits and side effects during titration is a common error 1

Food Considerations

• Adderall XR shows markedly lower amphetamine concentrations when taken with high-fat meals, so maintain consistent administration timing with or without food 2

Alternative Considerations

• If adequate response is not achieved after reaching the maximum dose of 50mg, or if intolerable side effects occur, consider switching to methylphenidate-based stimulants or adding non-stimulant medications like atomoxetine 1
• More than 90% of patients respond to one of the psychostimulant classes when both amphetamine and methylphenidate formulations are properly tried 1