Atomoxetine

Selective NRI — the only FDA-approved non-stimulant ADHD med for adults; A-tier for ADHD (effect size ~0.45 vs placebo, less acceptable than stimulants), but slow (4-8 weeks for full effect), modest cognitive impact in healthy adults (one small inhibitory-control signal), and outperformed by modafinil on most cognitive endpoints. For Dylan: SKIP-FOR-NOW — no ADHD diagnosis, modafinil already in V5 plan covers the same niche faster and better.

Atomoxetine is a selective norepinephrine reuptake inhibitor (NRI) — it blocks the presynaptic norepinephrine transporter (NET), preventing reuptake of NE and increasing synaptic NE concentrations throughout the brain.

The PFC dopamine trick (most important nuance):

• NE and DA share the same transporter (NET) in the prefrontal cortex, because PFC has minimal DAT expression
• Therefore NET blockade in PFC raises BOTH NE and DA in that region
• In the striatum and nucleus accumbens (the reward/abuse-relevant regions), DAT is dominant — atomoxetine has effectively no effect there
• Result: PFC executive-function-relevant DA increases without striatal DA increases → cognitive benefit profile without abuse liability
• This is why atomoxetine is unscheduled while methylphenidate and amphetamines are Schedule II

Onset kinetics:

• Tmax: 1-2 hours
• Half-life: 5.2 hours in CYP2D6 extensive metabolizers; 21.6 hours in poor metabolizers (4× longer)
• Initial therapeutic effects: 1-4 weeks
• Full therapeutic effect: additional 2-4 weeks (so 4-8 weeks total)
• Unlike stimulants, no acute "on/off" feel — effect builds over weeks of steady-state exposure

Why the slow onset: Norepinephrine system adaptation. Acute NET blockade increases synaptic NE immediately, but the downstream changes that produce clinical benefit (postsynaptic adrenergic receptor adaptations, locus coeruleus firing pattern changes, network-level effects on attention circuitry) take weeks to consolidate. This is fundamentally different from amphetamine/methylphenidate which act acutely on dopaminergic reward/motivation circuits.