Can a patient with Attention Deficit Hyperactivity Disorder (ADHD) take 2 pills of dextroamphetamine (amphetamine) 5 mg instead of amphetamine salts 10 mg?

Can the patient take 2 pills of dextroamphetamine 5 mg instead of amphetamine salts 10 mg?

Yes, taking 2 pills of dextroamphetamine 5 mg (total 10 mg) is a reasonable substitution for amphetamine salts 10 mg, though the clinical effects may differ slightly because dextroamphetamine is a single-isomer formulation while amphetamine salts contain a 3:1 ratio of dextro- to levo-amphetamine isomers. 1, 2

Understanding the Medication Difference

• Dextroamphetamine is the pure dextro-isomer of amphetamine, while amphetamine salts (Adderall) contain 75% dextroamphetamine and 25% levoamphetamine 3
• Both medications have FDA approval for ADHD treatment with identical starting doses (2.5-5 mg) and maximum daily doses (40 mg for children, up to 50 mg for adults) 1, 2
• The FDA labeling for both medications specifies the same dosing schedule: starting at 5 mg once or twice daily for patients 6 years and older, with weekly titration in 5 mg increments 1, 2

Practical Substitution Considerations

• The total daily amphetamine dose remains equivalent at 10 mg, making this a straightforward milligram-for-milligram substitution 1, 2
• However, dextroamphetamine may produce greater effects on appetite and sleep compared to methylphenidate due to its longer excretion half-life, and this may be more pronounced than with mixed amphetamine salts 4
• The levoamphetamine component in mixed salts may provide additional peripheral sympathomimetic effects that pure dextroamphetamine lacks, though the clinical significance of this difference varies by individual 3

Monitoring After Substitution

• Reassess ADHD symptom control within 1-2 weeks using standardized rating scales, as the slightly different pharmacologic profile may alter therapeutic response 5, 6
• Monitor for changes in side effects, particularly appetite suppression, insomnia, and cardiovascular parameters (blood pressure and pulse), as dextroamphetamine may produce different tolerability patterns 4, 6
• If symptom control worsens or side effects increase, consider returning to the original mixed amphetamine salts formulation rather than increasing the dextroamphetamine dose 7

Critical Pitfalls to Avoid

• Do not assume automatic equivalence in therapeutic response—while the total amphetamine content is the same, individual patients may respond differently to the isomer composition 3
• Avoid evening doses of either formulation to minimize insomnia, with all doses ideally given before 4 PM 1, 2
• Do not increase the dose prematurely if switching medications—allow at least one week at the equivalent dose to properly evaluate response before making any adjustments 6, 7
• Monitor for paradoxical worsening—some patients experience decreased focus with formulation changes, requiring return to the original medication 7