methylphenidate

Methylphenidate is a sympathomimetic amine that inhibits presynaptic dopamine and norepinephrine transporters (DAT and NET), increasing extracellular concentrations of these neurotransmitters in the prefrontal cortex and striatum. This enhances executive function, attention, and impulse control, making it a first-line treatment for attention-deficit/hyperactivity disorder (ADHD) in children and adults. It is also used for narcolepsy due to its wake-promoting effects.

Pharmacokinetics: Available in immediate-release and extended-release formulations (e.g., Concerta, Ritalin, Daytrana patch), allowing flexible dosing schedules. It undergoes hepatic metabolism via de-esterification (not primarily CYP-mediated) to inactive ritalinic acid.

Adverse effects: Insomnia, decreased appetite/weight loss, growth suppression in children (controversial, often reversible), increased heart rate and blood pressure, and potential for anxiety or irritability. Rare but serious effects include psychosis, priapism, and cardiovascular events (caution in patients with structural heart disease).

Abuse potential: Schedule II controlled substance due to potential for misuse, dependence, and diversion, particularly in academic or performance-enhancing contexts. Chronic misuse can lead to tolerance and stimulant use disorder.

Contraindications: Should be avoided in patients with severe anxiety, glaucoma, motor tics/Tourette syndrome (relative), and significant cardiovascular disease. Caution with MAOIs due to risk of hypertensive crisis.

Clinical pearls for boards: Differentiate from amphetamines (which also block reuptake but additionally promote neurotransmitter release via VMAT2 inhibition and reverse transport). Methylphenidate primarily blocks reuptake without significant release-promoting activity. Know the paradoxical calming effect in ADHD patients versus stimulant effects in non-ADHD individuals.