both increase sedation. Use Caution/Monitor.estazolam and perphenazine both increase sedation. Use Caution/Monitor.ethanolperphenazine and ethanol both increase sedation. Use Caution/Monitor.amitriptyline and ethanol both increase sedation. Use Caution/Monitor.etomidateetomidate and amitriptyline both increase sedation. Use Caution/Monitor.etomidate and perphenazine both increase sedation. Use Caution/Monitor.etravirineetravirine will increase the level or effect of amitriptyline by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.fedratinibfedratinib will increase the level or effect of perphenazine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP2D6 substrates as necessary.ezogabineezogabine, amitriptyline. Either increases toxicity of the other by QTc interval. Use Caution/Monitor. Slight and transient QT-prolongation observed with ezogabine, particularly when dose titrated to 1200 mg/day. QT interval should be monitored when ezogabine is prescribed with agents known to increase QT interval.fedratinibfedratinib will increase the level or effect of amitriptyline by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP2D6 substrates as necessary.felbamatefelbamate will increase the level or effect of amitriptyline by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.felodipinefelodipine will increase the level or effect of amitriptyline by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.fenfluramineperphenazine increases and fenfluramine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.amitriptyline increases and fenfluramine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.amitriptyline and fenfluramine both increase serotonin levels. Modify Therapy/Monitor Closely.perphenazine, fenfluramine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.fenfluramine, amitriptyline. Either increases effects of the other by serotonin levels. Use Caution/Monitor. Coadministration with drugs that increase serotoninergic effects may increase the risk of serotonin syndrome.fentanylfentanyl, perphenazine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).fesoterodinefesoterodine and amitriptyline both decrease cholinergic effects/transmission. Modify Therapy/Monitor Closely.fesoterodinefesoterodine 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.fingolimodfingolimod and perphenazine both increase QTc interval. Use Caution/Monitor.fingolimod and amitriptyline both increase QTc interval. Use Caution/Monitor.flavoxateperphenazine increases effects of flavoxate by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.flavoxate and amitriptyline both decrease cholinergic effects/transmission. Modify Therapy/Monitor Closely.flavoxate decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.flavoxate decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.flecainideamitriptyline and flecainide both increase QTc interval. Modify Therapy/Monitor Closely.perphenazine will increase the level or effect of flecainide by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.perphenazine and flecainide both increase QTc interval. Modify Therapy/Monitor Closely.flibanserinflibanserin, perphenazine. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).fluconazolefluconazole will increase the level or effect of amitriptyline by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.fluconazole will increase the level or effect of amitriptyline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.fluoxetineamitriptyline and fluoxetine both increase QTc interval. Modify Therapy/Monitor Closely.fluphenazinefluphenazine and perphenazine both increase sedation. Use Caution/Monitor.fluphenazine and amitriptyline both increase sedation. Use Caution/Monitor.fluphenazine and perphenazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.flurazepamflurazepam and perphenazine both increase sedation. Use Caution/Monitor.flurazepam and amitriptyline both increase sedation. Use Caution/Monitor.fluvoxaminefluvoxamine and perphenazine both increase QTc interval. Use Caution/Monitor.fluvoxamine and amitriptyline both increase QTc interval. Modify Therapy/Monitor Closely.formoterolperphenazine increases and formoterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.amitriptyline increases and formoterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.fosamprenavirfosamprenavir will increase the level or effect of amitriptyline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.foscarnetperphenazine and foscarnet both increase QTc interval. Modify Therapy/Monitor Closely.fosaprepitantfosaprepitant will increase the level or effect of amitriptyline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.foscarnetamitriptyline and foscarnet both increase QTc interval. Modify Therapy/Monitor Closely.fosphenytoinfosphenytoin will decrease the level or effect of amitriptyline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.fosphenytoin will decrease the level or effect of amitriptyline by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.fostemsaviramitriptyline and fostemsavir both increase QTc interval. Use Caution/Monitor. QTc prolongation reported with higher than recommended doses of fostemsavir. frovatriptanfrovatriptan, perphenazine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).frovatriptan and amitriptyline both increase serotonin levels. Modify Therapy/Monitor Closely.gabapentingabapentin, amitriptyline. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of CNS depressants can result in serious, life-threatening, and fatal respiratory depression. Use lowest dose possible and monitor for respiratory depression and sedation.ganaxoloneperphenazine and ganaxolone both increase sedation. Use Caution/Monitor.gabapentin enacarbilgabapentin enacarbil, amitriptyline. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of CNS depressants can result in serious, life-threatening, and fatal respiratory depression. Use lowest dose possible and monitor for respiratory depression and sedation.galantaminegalantamine increases and amitriptyline decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.ganaxoloneamitriptyline and ganaxolone both increase sedation. Use Caution/Monitor.gemifloxacingemifloxacin and perphenazine both increase QTc interval. Use Caution/Monitor.gemifloxacin and amitriptyline both increase QTc interval. Use Caution/Monitor.gilteritinibgilteritinib and amitriptyline both increase QTc interval. Use Caution/Monitor.gilteritinib and perphenazine both increase QTc interval. Use Caution/Monitor.glecaprevir/pibrentasvirglecaprevir/pibrentasvir will increase the level or effect of amitriptyline by P-glycoprotein (MDR1) efflux transporter. Modify Therapy/Monitor Closely.glycopyrrolateperphenazine increases toxicity of glycopyrrolate by unknown mechanism. Use Caution/Monitor.perphenazine increases effects of glycopyrrolate by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.glycopyrrolateglycopyrrolate and amitriptyline both decrease cholinergic effects/transmission. Modify Therapy/Monitor Closely.amitriptyline increases levels of glycopyrrolate by unknown mechanism. Use Caution/Monitor.glycopyrrolate inhaledperphenazine increases toxicity of glycopyrrolate inhaled by unknown mechanism. Use Caution/Monitor.glycopyrrolate inhaled decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.perphenazine increases effects of glycopyrrolate inhaled by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.glycopyrrolate inhaled decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.amitriptyline increases levels of glycopyrrolate inhaled by unknown mechanism. Use Caution/Monitor.glycopyrrolate inhaled and amitriptyline both decrease cholinergic effects/transmission. Modify Therapy/Monitor Closely.glycopyrronium tosylate topicalglycopyrronium tosylate topical, amitriptyline. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration of glycopyrronium tosylate topical with other anticholinergic medications may result in additive anticholinergic adverse effects.glycopyrronium tosylate topical, perphenazine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration of glycopyrronium tosylate topical with other anticholinergic medications may result in additive anticholinergic adverse effects.granisetrongranisetron and perphenazine both increase QTc interval. Use Caution/Monitor.grapefruitgrapefruit will increase the level or effect of amitriptyline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.guanfacineguanfacine, perphenazine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.haloperidolhaloperidol and perphenazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.haloperidol and amitriptyline both increase sedation. Use Caution/Monitor.perphenazine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.haloperidol and perphenazine both increase sedation. Use Caution/Monitor.henbanehenbane decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.henbane decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.henbane and amitriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.perphenazine increases effects of henbane by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.homatropinehomatropine decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.homatropine decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.perphenazine increases effects of homatropine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.homatropine and amitriptyline both decrease cholinergic effects/transmission. Modify Therapy/Monitor Closely.huperzine Ahuperzine A increases and amitriptyline decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.hydrocodoneperphenazine will increase the level or effect of hydrocodone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Hydromorphone (<3% of the circulating parent hydrocodone) is mainly formed by CYP2D6 mediated O-demethylation of hydrocodone. Hydromorphone may contribute to the total analgesic effect of hydrocodone.hydrocodonehydrocodone, amitriptyline. Either increases effects of the other by serotonin levels. Use Caution/Monitor. Coadministration of drugs that affect the serotonergic neurotransmitter system may result in serotonin syndrome. If concomitant use is warranted, carefully observe the patient, particularly during treatment initiation and dose adjustment.hydromorphoneperphenazine will increase the level or effect of hydromorphone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.hydromorphone and perphenazine both increase sedation. Use Caution/Monitor.hydromorphone and amitriptyline both increase sedation. Use Caution/Monitor.hydroxyzinehydroxyzine and amitriptyline both increase sedation. Use Caution/Monitor.hydroxyzine and amitriptyline both increase QTc interval. Use Caution/Monitor.hydroxyzine and perphenazine both increase QTc interval. Use Caution/Monitor.hydroxyzine and perphenazine both increase sedation. Use Caution/Monitor.hyoscyaminehyoscyamine and amitriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.hyoscyamine decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.hyoscyamine decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.perphenazine increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.hyoscyamine sprayperphenazine increases effects of hyoscyamine spray by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.hyoscyamine spray and amitriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.hyoscyamine spray decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.hyoscyamine spray decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.iloperidoneperphenazine and iloperidone both increase QTc interval. Modify Therapy/Monitor Closely.iloperidone and perphenazine both increase sedation. Use Caution/Monitor.perphenazine will increase the level or effect of iloperidone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.amitriptyline and iloperidone both increase QTc interval. Modify Therapy/Monitor Closely.iloperidone and perphenazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.iloperidone and amitriptyline both increase sedation. Use Caution/Monitor.imipramineamitriptyline and imipramine both decrease cholinergic effects/transmission. Use Caution/Monitor.perphenazine and imipramine both increase sedation. Use Caution/Monitor.amitriptyline and imipramine both increase sedation. Use Caution/Monitor.perphenazine will increase the level or effect of imipramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.incobotulinumtoxinAperphenazine, incobotulinumtoxinA. 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.indacaterol, inhaledindacaterol, inhaled, amitriptyline. QTc interval. Use Caution/Monitor. Indacaterol should be administered with extreme caution to patients treated with TCAs. Drugs that are known to prolong the QTc interval may have an increased the risk of ventricular arrhythmias.indacaterol, inhaledindacaterol, inhaled, perphenazine. QTc interval. Use Caution/Monitor. Drugs that are known to prolong the QTc interval may have an increased the risk of ventricular arrhythmias.indinavirindinavir will increase the level or effect of amitriptyline by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.insulin degludecperphenazine decreases effects of insulin degludec by Other (see comment). Use Caution/Monitor. Comment: Phenothiazines may increase blood glucose concentrations.insulin degludec/insulin aspartperphenazine decreases effects of insulin degludec/insulin aspart by Other (see comment). Use Caution/Monitor. Comment: Phenothiazines may increase blood glucose concentrations.insulin inhaledperphenazine decreases effects of insulin inhaled by Other (see comment). Use Caution/Monitor. Comment: Phenothiazines may increase blood glucose concentrations.ipratropiumipratropium and amitriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor. Due to the poor systemic absorption of ipratropium, interaction unlikely at regularly recommended dosages.ipratropium decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.ipratropium decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.perphenazine increases effects of ipratropium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.isofluraneisoflurane and amitriptyline both increase QTc interval. Use Caution/Monitor.isoflurane and perphenazine both increase QTc interval. Use Caution/Monitor.isoniazidisoniazid will increase the level or effect of amitriptyline by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.amitriptyline and isoniazid both increase serotonin levels. Modify Therapy/Monitor Closely.isoproterenolperphenazine increases and isoproterenol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.perphenazine, isoproterenol. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.isoproterenolamitriptyline increases and isoproterenol decreases sedation. Effect of interaction is not clear, use caution.