Increased plasma conc w/ CYP3A4 inhibitors eg, azole antifungals (itraconazole), midecamycin, ritonavir, ciclosporin, nifedipine, cimetidine, grapefruit juice. Enhanced CNS adverse reactions w/ hypnotics, anxiolytics, antidepressants, antipsychotics, antiepileptics. Reinforced or decreased effect w/ opioids. Inhibited P-gp-mediated transport w/ ketoconazole, verapamil HCl, cyclosporine, tacrolimus, cetirizine HCl.