DARIFENACIN AND SSRIS

Paroxetine increases the AUC of darifenacin by a modest 33%, which is unlikely to be clinically relevant.
No dosage adjustments are recommended by the US manufacturer. The UK manufacturer recommends that the dose of darifenacin should be started at 7.5 mg daily and, if well tolerated, titrated to 15 mg. This seems a cautious approach. Bear in mind the possibility of an interaction if antimuscarinic effects (dry mouth, constipation, drowsiness) are increased.