Table 2. [DPWG Atomoxetine Dosing based on CYP2D6 Phenotype (2016)]. - Medical Genetics Summaries

CYP2D6 metabolizer phenotype	Dosing recommendations
Ultrarapid	Be extra alert to reduced efficacy of the treatment Advise the individual to contact their doctor in the event of inadequate effect An alternative can be selected as a precaution. Clonidine is not metabolized by CYP2D6
Intermediate	In the event of side effects occurring and/or a response later than 9 weeks: reduce the dose and check whether the effect is conserved The plasma concentration of atomoxetine is a factor of 2-3 times higher for intermediate metabolizer than for normal metabolizer at the same dose
Poor	Start with the normal initial dose, bearing in mind that an increase in this dose probably will not be required Advise the individual to seek contact if side effects occur (such as decreased appetite, vomiting, abdominal pain, constipation, insomnia, early waking, drowsiness, irritability, pupil dilation and itching) If the medicine is effective, but side effects occur reduce the dose and check whether the effect is conserved The plasma concentration of atomoxetine is a factor of 8–11 times higher for poor metabolizer than for normal metabolizer at the same dose

CYP2D6 metabolizer phenotype

Dosing recommendations

Ultrarapid

Be extra alert to reduced efficacy of the treatment
Advise the individual to contact their doctor in the event of inadequate effect
An alternative can be selected as a precaution. Clonidine is not metabolized by CYP2D6

Intermediate

In the event of side effects occurring and/or a response later than 9 weeks: reduce the dose and check whether the effect is conserved
The plasma concentration of atomoxetine is a factor of 2-3 times higher for intermediate metabolizer than for normal metabolizer at the same dose

Poor

Start with the normal initial dose, bearing in mind that an increase in this dose probably will not be required
Advise the individual to seek contact if side effects occur (such as decreased appetite, vomiting, abdominal pain, constipation, insomnia, early waking, drowsiness, irritability, pupil dilation and itching)
If the medicine is effective, but side effects occur reduce the dose and check whether the effect is conserved
The plasma concentration of atomoxetine is a factor of 8–11 times higher for poor metabolizer than for normal metabolizer at the same dose

From: Atomoxetine Therapy and CYP2D6 Genotype

Medical Genetics Summaries [Internet].

Pratt VM, Scott SA, Pirmohamed M, et al., editors.

Bethesda (MD): National Center for Biotechnology Information (US); 2012-.

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