Would a 40mg dose of Adderall (dextroamphetamine and levoamphetamine) test positive for both d and L enantiomers on a drug screen and what are the expected amphetamine levels halfway through a month of treatment?

Adderall Drug Testing: Enantiomer Detection and Expected Levels

Direct Answer to Drug Screen Detection

Yes, 40 mg of Adderall will test positive for both d- and l-amphetamine enantiomers on a drug screen, as Adderall is formulated as a 3:1 mixture (approximately 76% d-amphetamine and 24% l-amphetamine salts), which distinguishes it from pure dextroamphetamine preparations. 1, 2

Enantiomer Composition on Drug Testing

• Adderall contains both d- and l-enantiomers in a fixed ratio, differentiating it from medications like Dexedrine that contain only d-amphetamine 1, 2
• The presence of l-amphetamine is the key distinguishing feature that separates Adderall from illicit amphetamine (which is often racemic or predominantly d-enantiomer) and other ADHD medications 1, 2
• The d-enantiomer will be in excess of the l-enantiomer throughout treatment, with the proportion of l-enantiomer gradually increasing over time as metabolism progresses 1, 2
• For compliance monitoring with approved ADHD medications containing only d-amphetamine, the proposed l-amphetamine cutoff is less than 1%, but Adderall will show significantly higher l-amphetamine percentages (approximately 24%) due to its formulation 3

Expected Amphetamine Levels During Chronic Treatment

Peak Concentrations After Single Dose

• Following a single 20 mg dose, peak amphetamine concentrations ranged from 2,645 to 5,948 ng/mL in urine 1
• Samples containing ≥500 ng/mL (the administrative cutoff for positive results) were detected up to 47.5 hours post-dose 1

Steady-State Levels with Repeated Dosing

• With repeated daily 20 mg dosing, peak concentrations increased to 5,739 to 19,172 ng/mL, demonstrating accumulation with chronic use 2
• Following the last dose of a five-day regimen, samples containing ≥500 ng/mL were detected up to 60 hours post-dose 2
• For a 40 mg daily dose (double the studied dose), proportionally higher concentrations would be expected, though individual variability is substantial 2

Halfway Through Monthly Treatment (Day 15)

• At steady state (typically achieved within 5-7 days), amphetamine levels would be at their maximum trough concentrations before the next dose 2
• Expected trough levels would likely range from 1,000 to 10,000+ ng/mL based on the 20 mg data, with 40 mg producing proportionally higher levels, though significant inter-individual variability exists 2
• The d-enantiomer remains predominant throughout chronic treatment, maintaining the approximately 3:1 ratio characteristic of Adderall 2

Critical Interpretation Considerations

Immunoassay Limitations

• Not all samples containing ≥500 ng/mL total amphetamine test positive on immunoassay screening due to differing cross-reactivity between d- and l-enantiomers 1, 2
• Confirmatory testing by GC-MS is necessary for accurate quantification and enantiomer differentiation 1, 2

Clinical False-Positive Context

• A patient taking Adderall for ADHD will have a positive amphetamine test result, which represents appropriate medical use rather than substance abuse 4
• Drug testing cannot distinguish between appropriate use and misuse of prescribed medications 4
• Complete medical history including prescribed medications is essential for accurate interpretation 4

Concentration Variability Factors

• Drug concentration profiles are highly variable within and between subjects due to:
  • Urine dilution effects 1, 2
  • Fluctuations in urine pH (affects amphetamine excretion) 1, 2
  • Individual metabolic differences 1, 2
  • Timing of sample collection relative to dosing 1, 2

Practical Monitoring Recommendations

• Chiral analysis reporting should include total amphetamine concentration and the relative amount of l-amphetamine rather than just the L/D ratio 3
• For Adderall compliance monitoring, expect l-amphetamine to comprise approximately 20-30% of total amphetamine (reflecting the 3:1 formulation ratio) 1, 2
• Oral fluid testing is a less invasive alternative to urine, though amphetamine concentrations are generally lower 3
• When test results do not correlate with clinical findings, seek assistance from the testing laboratory for proper interpretation 4