Atomoxetine

1. Indications
   1. Attention Deficit Hyperactivity Disorder (ADHD)
2. Contraindications
   1. Narrow-angle Glaucoma
   2. Concurrent MAO inhibitor use
3. Precautions
   1. Increased Suicidality in children and teens (FDA black box warning)
4. Mechanism
   1. Selective Norepinephrine reuptake inhibitor
   2. Non-stimulant (not a controlled substance)
5. Pharmacokinetics
   1. Peak serum concentration
      1. Without food: 1 hour
      2. With food: 3 hours
   2. Metabolized by CYP2D6
   3. Half-life
      1. Most patients: 5 hours
      2. CYP2D6 defect (5-10%): 24 hours
   4. Adjust dose to 50% if Hepatic dysfunction
6. Dosing: Indicated for ADHD in Age 6 years and older
   1. Timing
      1. Once daily dosing or
      2. Split daily dose to bid (morning and late afternoon)
   2. Weight <70 kg
      1. Initial: 0.5 mg/kg/day
      2. Increase after 3 days to 1.2 mg/kg/day
         1. Delay increasing dose if on CYP2D6 inhibitor
         2. See drug interactions below
      3. Maximum: 1.4 mg/kg/day up to 100 mg
   3. Weight >70 kg
      1. Initial: 40 mg/day
      2. Increase after 3 days to 80 mg/day
         1. Delay increasing dose if on CYP2D6 inhibitor
         2. See drug interactions below
      3. Maximum: 100 mg/day
7. Efficacy: Not considered a first line agent
   1. Superior to Placebo
   2. As effective as Methylphenidate
      1. Anecdotally does not show immediate effect as Ritalin
   3. References
      1. Kratochvil (2002) J Am Acad Child Adolesc Psychiatry
      2. Michelson (2001) Pediatrics 108:83
      3. Spencer (2002) J Clin Psychiatry 63:1140
8. Adverse Effects
   1. Severe liver injury
      1. Serious reactions, but case reports only as of 2005
      2. Observe clinically, but no routine LFT monitoring
      3. (February 2005) Prescriber's Letter, p. 8
   2. Abdominal Pain
   3. Gastrointestinal upset
      1. Nausea
      2. Vomiting (more than with Methylphenidate)
   4. Diminished appetite
   5. Dizziness
   6. Somnolence (more than with Methylphenidate)
   7. Weight loss (3.5% weight loss in 20% of patients)
   8. Anticholinergic effects in adults
      1. Dry Mouth
      2. Constipation
      3. Urinary Retention
      4. Sexual dysfunction
9. Drug Interactions
   1. MAO inhibitor
   2. Concurrent use of potent CYP2D6 inhibitors
      1. Paroxetine (Paxil)
      2. Fluoxetine (Prozac)
      3. Quinidine
10. Preparations
    1. Capsules: 10 mg, 18 mg, 25 mg, 40 mg, 60 mg
11. References
    1. (2003) Lexi-Comp Drug Database for Pocket PC (7/9/03)
    2. (2003) Med Lett Drugs Ther 45(1149):11-2