Paroxetine increases the AUC and levels of
atomoxetine by 6.5-fold and 3.5-fold, respectively by inhibiting its
metabolism by CYP2D6. Terbinafine, also a CYP2D6 inhibitor, is expected to interact similarly.
The
atomoxetine dose should be titrated slowly with the dose increased only if
symptoms fail to improve and if the initial dose is well tolerated. The UK manufacturers say that the initial dose should be maintained for a minimum of 7 days before considering an increase.