effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.imatinibMinor (1)imatinib will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.imipramineMonitor Closely (1)fesoterodine and imipramine both decrease cholinergic effects/transmission. Use Caution/Monitor.indinavirMonitor Closely (1)indinavir will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.ipratropiumMonitor Closely (1)fesoterodine and ipratropium both decrease cholinergic effects/transmission. Use Caution/Monitor. Due to the poor systemic absorption of ipratropium, interaction unlikely at regularly recommended dosages.isoniazidMonitor Closely (1)isoniazid will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.itraconazoleContraindicated (1)itraconazole will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Coadministration in patients with renal or hepatic impairment may result in increased fesoterodine levels and increased risk for potentially fatal adverse events.ketoconazoleSerious - Use Alternative (1)ketoconazole will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.lapatinibMonitor Closely (1)lapatinib will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.levodopaMinor (1)fesoterodine, levodopa. Other (see comment). Minor/Significance Unknown. Comment: Anticholinergic agents may enhance the therapeutic effects of levodopa; however, anticholinergic agents can exacerbate tardive dyskinesia. In high dosage, anticholinergics may decrease the effects of levodopa by delaying its GI absorption. .levoketoconazoleSerious - Use Alternative (1)levoketoconazole will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.lofepramineMonitor Closely (1)fesoterodine and lofepramine both decrease cholinergic effects/transmission. Use Caution/Monitor.loxapineMonitor Closely (3)fesoterodine decreases levels of loxapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. fesoterodine decreases levels of loxapine by pharmacodynamic antagonism. Use Caution/Monitor. loxapine increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.loxapine inhaledMonitor Closely (2)loxapine inhaled increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. fesoterodine decreases levels of loxapine inhaled by pharmacodynamic antagonism. Use Caution/Monitor.lumefantrineMonitor Closely (2)lumefantrine will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. lumefantrine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.maprotilineMonitor Closely (1)fesoterodine and maprotiline both decrease cholinergic effects/transmission. Use Caution/Monitor.maravirocMinor (1)maraviroc will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.marijuanaMonitor Closely (1)marijuana will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Minor (1)marijuana will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.meclizineMonitor Closely (1)fesoterodine and meclizine both decrease cholinergic effects/transmission. Use Caution/Monitor.methscopolamineMonitor Closely (1)fesoterodine and methscopolamine both decrease cholinergic effects/transmission. Use Caution/Monitor.methylprednisoloneMonitor Closely (1)methylprednisolone will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.metronidazoleMonitor Closely (1)metronidazole will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.miconazole vaginalMonitor Closely (1)miconazole vaginal will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nafcillinMonitor Closely (1)nafcillin will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nefazodoneMonitor Closely (1)nefazodone will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.nelfinavirMonitor Closely (1)nelfinavir will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.neostigmineMonitor Closely (1)neostigmine increases and fesoterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.nevirapineMonitor Closely (1)nevirapine will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nifedipineMonitor Closely (1)nifedipine will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nilotinibMonitor Closely (1)nilotinib will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Minor (1)nilotinib will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.nortriptylineMonitor Closely (1)fesoterodine and nortriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.olanzapineMonitor Closely (3)fesoterodine decreases levels of olanzapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. fesoterodine decreases levels of olanzapine by pharmacodynamic antagonism. Use Caution/Monitor. olanzapine increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.oliceridineMonitor Closely (1)fesoterodine increases toxicity of oliceridine by Other (see comment). Use Caution/Monitor. Comment: Anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Monitor for signs of urinary retention or reduced gastric motility if oliceridine is coadministered with anticholinergics.onabotulinumtoxinAMonitor Closely (1)onabotulinumtoxinA and fesoterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.orphenadrineMonitor Closely (1)fesoterodine and orphenadrine both decrease cholinergic effects/transmission. Use Caution/Monitor.oxcarbazepineMonitor Closely (1)oxcarbazepine will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.oxybutyninMonitor Closely (1)fesoterodine and oxybutynin both decrease cholinergic effects/transmission. Use Caution/Monitor.oxybutynin topicalMonitor Closely (1)fesoterodine and oxybutynin topical both decrease cholinergic effects/transmission. Use Caution/Monitor.oxybutynin transdermalMonitor Closely (1)fesoterodine and oxybutynin transdermal both decrease cholinergic effects/transmission. Use Caution/Monitor.paliperidoneMonitor Closely (3)fesoterodine decreases levels of paliperidone by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. fesoterodine decreases levels of paliperidone by pharmacodynamic antagonism. Use Caution/Monitor. paliperidone increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.pancuroniumMonitor Closely (1)fesoterodine and pancuronium both decrease cholinergic effects/transmission. Use Caution/Monitor.parecoxibMinor (1)parecoxib will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.paroxetineMinor (1)paroxetine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.pentobarbitalMonitor Closely (1)pentobarbital will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.perphenazineMonitor Closely (3)fesoterodine decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. fesoterodine decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor. perphenazine increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.Minor (1)perphenazine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.phenobarbitalMonitor Closely (1)phenobarbital will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.phenytoinMonitor Closely (1)phenytoin will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.physostigmineMonitor Closely (1)physostigmine increases and fesoterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.pilocarpineMonitor Closely (1)pilocarpine increases and fesoterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.pimozideMonitor Closely (3)fesoterodine decreases levels of pimozide by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. fesoterodine decreases levels of pimozide by pharmacodynamic antagonism. Use Caution/Monitor. pimozide increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.posaconazoleMonitor Closely (1)posaconazole will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.prabotulinumtoxinAMonitor Closely (1)fesoterodine, prabotulinumtoxinA. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Use of anticholinergic drugs after administration of botulinum toxin-containing products may potentiate systemic anticholinergic effects.pralidoximeMonitor Closely (1)fesoterodine and pralidoxime both decrease cholinergic effects/transmission. Use Caution/Monitor.pramlintideSerious - Use Alternative (1)pramlintide, fesoterodine. Either increases effects of the other by pharmacodynamic synergism. Contraindicated. Synergistic inhibition of GI motility.prednisoneMonitor Closely (1)prednisone will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.primidoneMonitor Closely (1)primidone will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.prochlorperazineMonitor Closely (3)fesoterodine decreases levels of prochlorperazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. fesoterodine decreases levels of prochlorperazine by pharmacodynamic antagonism. Use Caution/Monitor. prochlorperazine increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.promethazineMonitor Closely (3)fesoterodine decreases levels of promethazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. fesoterodine decreases levels of promethazine by pharmacodynamic antagonism. Use Caution/Monitor. promethazine increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.propafenoneMinor (1)propafenone will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.propanthelineMonitor Closely (1)fesoterodine and propantheline both decrease cholinergic effects/transmission. Use Caution/Monitor.protriptylineMonitor Closely (1)fesoterodine and protriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.pyridostigmineMonitor Closely (1)pyridostigmine increases and fesoterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.quetiapineMonitor Closely (3)fesoterodine decreases levels of quetiapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. fesoterodine decreases levels of quetiapine by pharmacodynamic antagonism. Use Caution/Monitor. quetiapine increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.quinacrineMinor (1)quinacrine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.quinidineMonitor Closely (1)quinidine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.quinupristin/dalfopristinMonitor Closely (1)quinupristin/dalfopristin will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.ranolazineMinor (1)ranolazine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.rapacuroniumMonitor Closely (1)fesoterodine and rapacuronium both decrease cholinergic effects/transmission. Use Caution/Monitor.revefenacinSerious - Use Alternative (1)revefenacin and fesoterodine both decrease cholinergic effects/transmission. Avoid or Use Alternate Drug. Coadministration may cause additive anticholinergic effects.rifabutinSerious - Use Alternative (1)rifabutin will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.rifampinSerious - Use Alternative (1)rifampin will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.rifapentineMonitor Closely (1)rifapentine will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.risperidoneMonitor Closely (3)fesoterodine decreases levels of risperidone by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. fesoterodine decreases levels of risperidone by pharmacodynamic antagonism. Use Caution/Monitor. risperidone increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.ritonavirMonitor Closely (1)ritonavir will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Minor (1)ritonavir will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.rivastigmineMonitor Closely (1)fesoterodine decreases effects of rivastigmine by cholinergic effects/transmission. Use Caution/Monitor.rocuroniumMonitor Closely (1)fesoterodine and rocuronium both decrease cholinergic effects/transmission. Use Caution/Monitor.rufinamideMonitor Closely (1)rufinamide will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.scopolamineMonitor Closely (1)fesoterodine and scopolamine both decrease cholinergic effects/transmission. Use Caution/Monitor.secobarbitalMonitor Closely (1)secobarbital will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.secretinSerious - Use Alternative (1)fesoterodine decreases effects of secretin by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Concomitant use of anticholinergic drugs may cause a hyporesponse to stimulation testing with secretin. Discontinue anticholinergic drugs at least 5 half-lives before administering secretin.sertralineMinor (1)sertraline will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.solifenacinMonitor Closely (1)fesoterodine and solifenacin both decrease cholinergic effects/transmission. Use Caution/Monitor.St John's WortSerious - Use Alternative (1)St John's Wort will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.succinylcholineMonitor Closely (1)succinylcholine increases and fesoterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.terbinafineMonitor Closely (1)terbinafine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Assess need to reduce dose of CYP2D6-metabolized drug.thioridazineMonitor Closely (3)fesoterodine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. fesoterodine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor. thioridazine increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.Minor (1)thioridazine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.thiothixeneMonitor Closely (3)fesoterodine decreases levels of thiothixene by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. fesoterodine decreases levels of thiothixene by pharmacodynamic antagonism. Use Caution/Monitor. thiothixene increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.tiotropiumMonitor Closely (1)fesoterodine and tiotropium both decrease cholinergic effects/transmission. Use Caution/Monitor.tipranavirMinor (1)tipranavir will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.tolterodineMonitor Closely (1)fesoterodine and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.topiramateMonitor Closely (1)topiramate will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.trazodoneMinor (1)fesoterodine and trazodone both decrease cholinergic effects/transmission. Minor/Significance Unknown.trifluoperazineMonitor Closely (3)fesoterodine decreases levels of trifluoperazine by inhibition of GI