Comparative Pharmacology
Head-to-head clinical analysis: ADDERALL XR 20 versus BENZEDRINE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: ADDERALL XR 20 versus BENZEDRINE.
ADDERALL XR 20 vs BENZEDRINE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Adderall XR 20 is a combination of amphetamine enantiomers (dextroamphetamine and levoamphetamine). It increases synaptic levels of dopamine and norepinephrine by inhibiting their reuptake and promoting their release from presynaptic terminals.
Benzedrine (racemic amphetamine) releases dopamine and norepinephrine from presynaptic neurons, blocks their reuptake, and inhibits monoamine oxidase, increasing synaptic monoamine levels.
20 mg orally once daily in the morning.
Oral: 5-10 mg once or twice daily, maximum 40 mg/day. Intramuscular: 5-10 mg every 30-60 minutes as needed, maximum 40 mg/day.
None Documented
None Documented
Approximately 10-13 hours for d-amphetamine and 13-15 hours for l-amphetamine in adults; in children, 9-11 hours. The extended-release formulation provides a prolonged therapeutic effect masking shorter elimination.
Terminal elimination half-life: 4-6 hours in adults (range 4-8 hours). Clinically, duration of action correlates with half-life, but tolerance may develop with repeated dosing.
Approximately 90% of an oral dose is excreted renally, with 30% as unchanged amphetamine and the remainder as metabolites (including hippuric acid, benzoic acid, and hydroxylated derivatives). Fecal/biliary excretion accounts for <10%.
Renal (30-40% unchanged, pH-dependent), with minor biliary/fecal elimination. At acidic urine pH, elimination half-life is shortened; at alkaline pH, reabsorption increases.
Category C
Category C
CNS Stimulant
CNS Stimulant