Are dextroamphetamine and mixed amphetamine salts (e.g., Adderall) the same medication?

Dextroamphetamine and Mixed Amphetamine Salts Are Not the Same Medication

Dextroamphetamine and mixed amphetamine salts (Adderall) are distinct formulations with different compositions, though both are effective first-line treatments for ADHD. 1

Key Compositional Differences

• Mixed amphetamine salts (Adderall) contain a 3:1 ratio of dextroamphetamine to levoamphetamine, specifically including dextroamphetamine saccharate, amphetamine aspartate, dextroamphetamine sulfate, and amphetamine sulfate 1, 2
• Dextroamphetamine (Dexedrine) contains only the dextro-isomer of amphetamine, without any levo-isomer component 3
• The presence of approximately 25% L-amphetamine in Adderall creates pharmacological differences compared to pure dextroamphetamine 4

Pharmacological Distinctions

• The levo-amphetamine component in mixed salts changes dopamine release kinetics, producing significantly faster rise times and shorter signal decay times compared to dextroamphetamine alone 4
• L-amphetamine appears to have unique actions on the dopamine transporter that differ from the dextro-isomer, though it does not increase the amplitude of dopamine release 4
• Both formulations achieve 70-80% response rates when properly titrated, making them equally effective first-line options for ADHD 3, 5

Clinical Dosing Equivalence

• Dexedrine is typically dosed starting at 5 mg twice daily for immediate release or 10 mg once daily for extended-release formulations 3
• Adderall XR is started at 10 mg once daily in the morning, with typical therapeutic ranges of 10-50 mg daily in adults 3, 5
• The bioavailability and pharmacokinetic profiles of Adderall XR 20 mg are comparable to Adderall IR 10 mg twice daily 2

Practical Clinical Implications

• Both medications are considered equivalent first-line stimulant options with the same contraindications (MAO inhibitor use, symptomatic cardiovascular disease, active psychosis, uncontrolled hypertension) 5
• Approximately 40% of patients respond to both stimulant classes, while another 40% respond preferentially to one, so if one amphetamine formulation fails, trying the other before switching to methylphenidate is reasonable 5
• The choice between dextroamphetamine and mixed salts is often based on individual response patterns and tolerability rather than superior efficacy of one over the other 3, 5

Common Pitfall to Avoid

• Do not assume these medications are interchangeable at identical doses—while both are amphetamine-based stimulants, the different isomer ratios may produce distinct clinical effects in individual patients, and systematic titration is required for each formulation 5, 4