What is the difference between dextroamphetamine (amphetamine) 5 mg and amphetamine salts (mixed salts formulation) 10 mg in a patient with Attention Deficit Hyperactivity Disorder (ADHD)?

Dextroamphetamine 5 mg vs Amphetamine Salts 10 mg: Key Differences

Amphetamine salts 10 mg delivers twice the total amphetamine dose compared to dextroamphetamine 5 mg, and contains approximately 25% levoamphetamine which alters dopamine release kinetics, providing faster onset and shorter signal decay times compared to pure dextroamphetamine. 1

Composition and Pharmacological Differences

Active Ingredient Ratio

• Dextroamphetamine 5 mg contains only the dextro-isomer of amphetamine (100% d-amphetamine) 2
• Amphetamine salts 10 mg (Adderall) contains a 3:1 ratio of dextroamphetamine to levoamphetamine, meaning approximately 75% d-amphetamine and 25% l-amphetamine 3

Dopamine Release Characteristics

• The presence of l-amphetamine in mixed salts formulations does not increase the amplitude of dopamine release but significantly changes the kinetics 1
• Mixed amphetamine salts exhibit faster rise times and shorter signal decay times for dopamine release compared to pure dextroamphetamine 1
• This suggests l-amphetamine may have unique actions on the dopamine transporter that affect how dopamine is released from nerve terminals 1

Dosing Equivalence Considerations

Dose Conversion Guidelines

• The American Academy of Child and Adolescent Psychiatry guidelines indicate that dextroamphetamine and mixed-salts amphetamine are dosed identically on a milligram-per-milligram basis for ADHD treatment 4
• Adults or older adolescents may be started on doses of 5 mg of either dextroamphetamine or mixed-salts amphetamine, with titration upward in 5-10 mg intervals weekly 4
• Maximum daily doses for adults generally reach up to 0.9 mg/kg or 40 mg for both dextroamphetamine and mixed-salts amphetamine 4

Clinical Implications of Dose Difference

• Your 10 mg amphetamine salts dose is double the 5 mg dextroamphetamine dose, representing a significant dose escalation 4
• The American Academy of Child and Adolescent Psychiatry recommends titration in 5 mg increments weekly, making the jump from 5 mg to 10 mg appropriate if done systematically 5
• However, approximately 70% of patients respond when a full range of doses is properly titrated, and more than 90% respond when both stimulant classes are tried 5

Practical Clinical Differences

Duration and Onset (for immediate-release formulations)

• Both medications require dosing 2-3 times daily for immediate-release formulations to maintain symptom control throughout the day 4
• Children treated with mixed-salts amphetamine may require only once-daily dosing in some cases, though this varies by individual 4

Response Rates and Switching

• If a patient fails to respond to one stimulant or has prohibitive side effects, switching to an alternative stimulant is recommended 4
• Nearly 90% of patients will respond if both dextroamphetamine and methylphenidate are tried, though some may have unacceptable side effects 4

Critical Monitoring Considerations

Dose-Dependent Effects

• Overstimulation can paradoxically worsen attention and focus, causing increased distractibility, agitation, or cognitive inflexibility 5
• The American Academy of Child and Adolescent Psychiatry recognizes that not all patients benefit from higher doses, and optimal dosing must be determined by systematic assessment at each level 5
• If the 10 mg dose worsens function compared to 5 mg, return immediately to the lower dose and maintain for at least 1 week while using standardized ADHD rating scales 5

Vital Sign Monitoring

• Assess blood pressure and pulse at baseline and with each dose increase 5
• Evaluate both therapeutic effects (attention, focus, task completion) and side effects (appetite, sleep, mood, cardiovascular symptoms) before further adjustments 5

Common Pitfalls to Avoid

• Do not assume "more is better" if higher doses worsen function—this indicates overstimulation, not treatment failure 5
• Avoid continuing dose escalation beyond 40 mg/day (children) or 50 mg/day (adults) without considering a switch to methylphenidate, as more than 90% respond to one psychostimulant class when both are properly tried 5
• Do not fail to allow sufficient time (at least one week) between dose increases to properly evaluate response 5
• Avoid overlooking the importance of obtaining standardized ADHD rating scales from multiple settings before each dose adjustment 5