Atomoxetine (US brand name Strattera®) is a selective norepinephrine reuptake inhibitor. Here is basic information about this medication.
Other articles on this website with more advanced information and tips related to this medication are linked to under Related Pages below.
Mechanism of Action
Atomoxetine is an inhibitor of the norepinephrine reuptake transporter. In addition, it may also indirectly increase dopamine levels in the prefrontal cortex (Arnsten, 2011).
Attention deficit hyperactivity disorder (ADHD)
Mechanism of Action/ Pharmacodynamics
Atomoxetine is a selective norepinephrine reuptake inhibitor.
Atomoxetine is mainly metabolized by CYP2D6.
1. Children and adolescents up to 70 kg
Initial: 0.5 mg/kg per day
Target: 1.2 mg/kg per day
Maximum: 1.4 mg/kg per day
2. Children and adolescents over 70 kg and adults
Initial: 40 mg per day
Target: 80 mg per day
Maximum: 100 mg per day
1. May be taken with or without food
2. May be discontinued without tapering
Reduce initial and target dose to 50% of the normal dose for moderate hepatic insufficiency and 25% of the normal dose for severe hepatic insufficiency.
The Prescribing Information for atomoxetine recommends the following for children and adolescents up to 70 kg body weight who are known to be CYP2D6 poor metabolizers:
Starting dose: Atomoxetine should be started at 0.5 mg/kg/day in these patients.
Increasing the dose: In these patients, the dose of atomoxetine should only be increased to the usual target dose of 1.2 mg/kg/day if symptoms fail to improve after 4 weeks of treatment with the lower dose and the initial dose has been well tolerated.
What about CYP2D6 poor metabolizers who are adults or children and adolescents weighing 70 kg or more? Though the Prescribing Information is not clear about this, I think we should follow the dosing recommended for these patients if they are on a strong CYP2D6 inhibitor. That is, in these patients, atomoxetine should be “initiated at 40 mg/day and only increased to the usual target dose of 80 mg/day if symptoms fail to improve after 4 weeks and the initial dose is well tolerated.”
Here is the exact wording in the Prescribing Information:
“In children and adolescents up to 70 kg body weight administered strong CYP2D6 inhibitors, e.g., paroxetine, fluoxetine, and
quinidine, or in patients who are known to be CYP2D6 PMs, [atomoxetine] should be initiated at 0.5 mg/kg/day and only increased to the usual target dose of 1.2 mg/kg/day if symptoms fail to improve after 4 weeks and the initial dose is well
“In children and adolescents over 70 kg body weight and adults administered strong CYP2D6 inhibitors, e.g., paroxetine, fluoxetine, and quinidine, [atomoxetine] should be initiated at 40 mg/day and only increased to the usual target dose of 80 mg/day if symptoms fail to improve after 4 weeks and the initial dose is well tolerated.”
Potential side effects
Please see THIS PAGE for a handout listing both the common and less common side effects of this medication along with the percentages of patients who report them.
Dosage forms and strengths
Capsule: 10 mg, 18 mg, 25 mg, 40 mg, 60 mg, 80 mg, and 100 mg
Important! Please refer to the full Prescribing Information (see link below) before prescribing this medication.
Arnsten AFT. Catecholamine influences on dorsolateral prefrontal cortical networks. Biol Psychiatry 2011;69(12):e89–e99.
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