Red Hair and Stimulant Medication Metabolism

Pharmacokinetics of Stimulants

The American Academy of Child and Adolescent Psychiatry notes that methylphenidate undergoes de-esterification in plasma with rapid absorption, low plasma protein binding, and rapid extracellular metabolism, with pharmacokinetics characterized by a 3-hour plasma half-life 1, 2, 4
The American Academy of Child and Adolescent Psychiatry states that amphetamine/dextroamphetamine involves multiple metabolic pathways including p-hydroxylation, N-demethylation, deamination, and conjugation, with up to 80% excreted unchanged in urine and an 11-hour plasma half-life for dextroamphetamine 1, 2, 4

The American Academy of Pediatrics recommends that preschool-aged children (4-5 years) be given lower starting doses of stimulant medication with smaller incremental increases due to slower rates of metabolism 5, 6
The American Academy of Child and Adolescent Psychiatry notes that food effects may increase both absorption and bioavailability of stimulant medications after a meal 1, 4

The American Academy of Child and Adolescent Psychiatry recommends starting with 5 mg twice daily of methylphenidate and increasing by 5-10 mg weekly increments based on clinical response 7
The American Academy of Child and Adolescent Psychiatry and the American College of Obstetricians and Gynecologists suggest starting with 2.5-5 mg once or twice daily of amphetamine/dextroamphetamine and titrating by 5 mg weekly increments 7, 8
Maximum doses are typically 60 mg/day for methylphenidate and 40 mg/day for dextroamphetamine in adults, regardless of hair color 7, 4

The American Academy of Child and Adolescent Psychiatry recommends using ADHD rating scales to assess response and monitoring for common side effects including appetite suppression, insomnia, irritability, and cardiovascular effects 7
The American Academy of Child and Adolescent Psychiatry suggests assessing blood pressure, pulse, height, and weight at baseline and follow-up visits 7