- Subjects who require medications that inhibit the cytochrome P450 (CYP450) 2D6 pathway such as: Quinidine, Cimetidine, Type 1 antiarrhythmics, Phenothiazines, Selective serotonin reuptake inhibitors such as fluoxetine, paroxetine, and sertraline, reserpine, other anticholinergic drugs, and sympathomimetic drugs