Table 1

Retention time, molecular ions, and characteristic product ions of atomoxetine and its metabolites

CompoundHPLC Retention TimeMolecular IonCharacteristic Product Ions
min [M+H]+, m/z m/z
4-Hydroxy-N-desmethylatomoxetine-O-glucuronide6434330, 258, 206, 134, 30
4-Hydroxyatomoxetine-O-glucuronide6.5448272, 148, 44
4-Hydroxy-2-carboxyatomoxetine-O-glucuronide7478302, 148, 44
Dihydroxyatomoxetine-O-glucuronide (1)1-a 8464322, 288, 148, 44
Hydroxy-2-carboxyatomoxetine-O-glucuronide1-a 9478302, 148, 44
Hydroxyatomoxetine (1)1-a 11272254, 226, 155, 148, 117, 44
2-Hydroxymethylatomoxetine-O-glucuronide11448272, 150
Dihydroxyatomoxetine-O-glucuronide (2)1-a 11464288, 166, 44
4-Hydroxy-N-desmethylatomoxetine1-b 12258213, 134, 117, 105, 30
4-Hydroxyatomoxetine1-b 13272213, 148, 44
2-Hydroxymethylatomoxetine1-b 15272150, 107, 44
Hydroxyatomoxetine (2)1-b 16272150, 123, 115, 44
N-Desmethylatomoxetine1-b 19242197, 134, 105, 30
Atomoxetine1-b 20256197, 148, 133, 117, 44

  • ↵1-a  Specific hydroxylation sites for these metabolites have not been defined.

  • ↵1-b  HPLC retention time and fragmentation characteristics were identical to authentic standard.