increase sedation. Use Caution/Monitor. flurazepam and amitriptyline both increase sedation. Use Caution/Monitor.fluvoxamineMonitor Closely (2)fluvoxamine and perphenazine both increase QTc interval. Use Caution/Monitor. fluvoxamine and amitriptyline both increase QTc interval. Modify Therapy/Monitor Closely.Serious - Use Alternative (1)fluvoxamine and amitriptyline both increase serotonin levels. Avoid or Use Alternate Drug.formoterolMonitor Closely (2)perphenazine 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.Serious - Use Alternative (3)amitriptyline, formoterol. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron. perphenazine and formoterol both increase QTc interval. Avoid or Use Alternate Drug. amitriptyline and formoterol both increase QTc interval. Avoid or Use Alternate Drug.fosamprenavirMonitor Closely (1)fosamprenavir will increase the level or effect of amitriptyline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)fosamprenavir increases levels of amitriptyline by decreasing metabolism. Avoid or Use Alternate Drug.fosaprepitantMonitor Closely (1)fosaprepitant will increase the level or effect of amitriptyline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.foscarnetMonitor Closely (2)perphenazine and foscarnet both increase QTc interval. Modify Therapy/Monitor Closely. amitriptyline and foscarnet both increase QTc interval. Modify Therapy/Monitor Closely.fosinoprilMinor (1)perphenazine increases effects of fosinopril by unspecified interaction mechanism. Minor/Significance Unknown.fosphenytoinMonitor Closely (2)fosphenytoin will decrease the level or effect of amitriptyline by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. fosphenytoin will decrease the level or effect of amitriptyline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.fostemsavirMonitor Closely (1)amitriptyline and fostemsavir both increase QTc interval. Use Caution/Monitor. QTc prolongation reported with higher than recommended doses of fostemsavir. frovatriptanMonitor Closely (2)frovatriptan, 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.gabapentinMonitor Closely (1)gabapentin, 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.gabapentin enacarbilMonitor Closely (1)gabapentin 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.galantamineMonitor Closely (1)galantamine increases and amitriptyline decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.Minor (1)perphenazine will increase the level or effect of galantamine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.ganaxoloneMonitor Closely (2)amitriptyline and ganaxolone both increase sedation. Use Caution/Monitor. perphenazine and ganaxolone both increase sedation. Use Caution/Monitor.gemifloxacinMonitor Closely (2)gemifloxacin and amitriptyline both increase QTc interval. Use Caution/Monitor. gemifloxacin and perphenazine both increase QTc interval. Use Caution/Monitor.gilteritinibMonitor Closely (2)gilteritinib and amitriptyline both increase QTc interval. Use Caution/Monitor. gilteritinib and perphenazine both increase QTc interval. Use Caution/Monitor.givosiranSerious - Use Alternative (2)givosiran will increase the level or effect of perphenazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP2D6 substrates with givosiran. If unavoidable, decrease the CYP2D6 substrate dosage in accordance with approved product labeling. givosiran will increase the level or effect of amitriptyline by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP2D6 substrates with givosiran. If unavoidable, decrease the CYP2D6 substrate dosage in accordance with approved product labeling.glecaprevir/pibrentasvirMonitor Closely (1)glecaprevir/pibrentasvir will increase the level or effect of amitriptyline by P-glycoprotein (MDR1) efflux transporter. Modify Therapy/Monitor Closely.glimepirideMinor (1)amitriptyline increases effects of glimepiride by pharmacodynamic synergism. Minor/Significance Unknown.glipizideMinor (1)amitriptyline increases effects of glipizide by pharmacodynamic synergism. Minor/Significance Unknown.glyburideMinor (1)amitriptyline increases effects of glyburide by pharmacodynamic synergism. Minor/Significance Unknown.glycopyrrolateMonitor Closely (4)perphenazine increases effects of glycopyrrolate by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. amitriptyline increases levels of glycopyrrolate by unknown mechanism. Use Caution/Monitor. perphenazine increases toxicity of glycopyrrolate by unknown mechanism. Use Caution/Monitor. glycopyrrolate and amitriptyline both decrease cholinergic effects/transmission. Modify Therapy/Monitor Closely.glycopyrrolate inhaledMonitor Closely (6)perphenazine 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 topicalMonitor Closely (2)glycopyrronium 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.granisetronMonitor Closely (1)granisetron and perphenazine both increase QTc interval. Use Caution/Monitor.Serious - Use Alternative (2)granisetron, amitriptyline. Either increases toxicity of the other by serotonin levels. Avoid or Use Alternate Drug. granisetron and amitriptyline both increase QTc interval. Avoid or Use Alternate Drug.grapefruitMonitor Closely (1)grapefruit will increase the level or effect of amitriptyline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.griseofulvinMinor (1)griseofulvin will decrease the level or effect of amitriptyline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.guanfacineMonitor Closely (1)guanfacine, perphenazine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.Serious - Use Alternative (1)amitriptyline decreases effects of guanfacine by Other (see comment). Avoid or Use Alternate Drug. Comment: Inhibition of uptake by adrenergic neurons.haloperidolMonitor Closely (4)haloperidol 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.Serious - Use Alternative (2)amitriptyline and haloperidol both increase QTc interval. Avoid or Use Alternate Drug. perphenazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.Minor (1)haloperidol will increase the level or effect of perphenazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.henbaneMonitor Closely (4)henbane 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.homatropineMonitor Closely (4)homatropine 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 AMonitor Closely (1)huperzine A increases and amitriptyline decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.hydrocodoneMonitor Closely (2)hydrocodone, 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. perphenazine 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.Serious - Use Alternative (1)hydrocodone, perphenazine. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Profound sedation, respiratory depression, coma, and death may result if coadministered. Reserve concomitant prescribing of these drugs in patients for whom other treatment options are inadequate. Limit dosages and durations to the minimum required. Monitor closely for signs of respiratory depression and sedation. Increased risk of hypotension if ability to maintain blood pressure has been compromised by a reduced blood volume or concurrent administration of certain CNS depressant drugs (eg, phenothiazines or general anesthetics).hydrocortisoneMinor (1)hydrocortisone will decrease the level or effect of amitriptyline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.hydromorphoneMonitor Closely (3)perphenazine 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.hydroxychloroquine sulfateSerious - Use Alternative (2)hydroxychloroquine sulfate and amitriptyline both increase QTc interval. Avoid or Use Alternate Drug. hydroxychloroquine sulfate and perphenazine both increase QTc interval. Avoid or Use Alternate Drug.hydroxyprogesterone caproate (DSC)Minor (1)hydroxyprogesterone caproate (DSC), amitriptyline. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Estrogens and progestins may decr tricyclic antidepressant effects, while increasing TCA plasma concentration and adverse effects.hydroxyzineMonitor Closely (4)hydroxyzine 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.hyoscyamineMonitor Closely (4)hyoscyamine 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 sprayMonitor Closely (4)perphenazine 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.ibutilideContraindicated (2)perphenazine and ibutilide both increase QTc interval. Contraindicated. amitriptyline and ibutilide both increase QTc interval. Contraindicated.iloperidoneMonitor Closely (6)perphenazine 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.imatinibMinor (1)imatinib will increase the level or effect of perphenazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.imidaprilMinor (1)perphenazine increases effects of imidapril by unspecified interaction mechanism. Minor/Significance Unknown.imipramineMonitor Closely (4)amitriptyline 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.Serious - Use Alternative (3)amitriptyline and imipramine both increase QTc interval. Avoid or Use Alternate Drug. perphenazine and imipramine both increase QTc interval. Avoid or Use Alternate Drug. amitriptyline and imipramine both increase serotonin levels. Avoid or Use Alternate Drug.Minor (2)imipramine, perphenazine. Either increases levels of the other by decreasing metabolism. Minor/Significance Unknown. Additive anticholinergic effects. imipramine, perphenazine. Either increases levels of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive anticholinergic effects.incobotulinumtoxinAMonitor Closely (1)perphenazine, 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, inhaledMonitor Closely (2)indacaterol, 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, 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.indapamideContraindicated (2)perphenazine and indapamide both increase QTc interval. Contraindicated. amitriptyline and indapamide both increase QTc interval. Contraindicated.indinavirMonitor Closely (1)indinavir will increase the level or effect of amitriptyline by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.insulin aspartMinor (1)amitriptyline increases effects of insulin aspart by pharmacodynamic synergism. Minor/Significance Unknown.insulin degludecMonitor Closely (1)perphenazine decreases effects of insulin degludec by Other (see comment). Use Caution/Monitor. Comment: Phenothiazines may increase blood glucose concentrations.insulin degludec/insulin aspartMonitor Closely (1)perphenazine decreases effects of insulin degludec/insulin aspart by Other (see comment). Use Caution/Monitor. Comment: Phenothiazines may increase blood glucose concentrations.insulin detemirMinor (1)amitriptyline increases effects of insulin detemir by pharmacodynamic synergism. Minor/Significance Unknown.insulin