the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.mexiletineperphenazine will increase the level or effect of mexiletine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.midazolammidazolam and perphenazine both increase sedation. Use Caution/Monitor.midazolam and amitriptyline both increase sedation. Use Caution/Monitor.midazolam intranasalmidazolam intranasal, perphenazine. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Concomitant use of barbiturates, alcohol, or other CNS depressants may increase the risk of hypoventilation, airway obstruction, desaturation, or apnea and may contribute to profound and/or prolonged drug effect.midazolam intranasal, amitriptyline. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Concomitant use of barbiturates, alcohol, or other CNS depressants may increase the risk of hypoventilation, airway obstruction, desaturation, or apnea and may contribute to profound and/or prolonged drug effect.midodrineperphenazine, midodrine. 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.perphenazine increases and midodrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.amitriptyline increases and midodrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.mifepristonemifepristone, perphenazine. QTc interval. Modify Therapy/Monitor Closely. Use alternatives if available.mifepristone, amitriptyline. QTc interval. Modify Therapy/Monitor Closely. Use alternatives if available.milnacipranmilnacipran, 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).mipomersenmipomersen, amitriptyline. Either increases toxicity of the other by Other (see comment). Use Caution/Monitor. Comment: Both drugs have potential to increase hepatic enzymes; monitor LFTs.mirabegronmirabegron will increase the level or effect of perphenazine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.mirabegron will increase the level or effect of amitriptyline by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.mirtazapineperphenazine and mirtazapine both increase sedation. Use Caution/Monitor.amitriptyline and mirtazapine both increase serotonin levels. Modify Therapy/Monitor Closely.amitriptyline and mirtazapine both increase sedation. Use Caution/Monitor.mirtazapine and perphenazine both increase QTc interval. Use Caution/Monitor.modafinilperphenazine increases and modafinil decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.amitriptyline increases and modafinil decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.modafinil will increase the level or effect of amitriptyline by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.morphineperphenazine will increase the level or effect of morphine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.amitriptyline and morphine both increase serotonin levels. Modify Therapy/Monitor Closely.morphine and perphenazine both increase sedation. Use Caution/Monitor.morphine and amitriptyline both increase sedation. Use Caution/Monitor.motherwortperphenazine and motherwort both increase sedation. Use Caution/Monitor.amitriptyline and motherwort both increase sedation. Use Caution/Monitor.moxonidineperphenazine and moxonidine both increase sedation. Use Caution/Monitor.amitriptyline and moxonidine both increase sedation. Use Caution/Monitor.nabiloneperphenazine and nabilone both increase sedation. Use Caution/Monitor.amitriptyline and nabilone both increase sedation. Use Caution/Monitor.nalbuphinenalbuphine and amitriptyline both increase sedation. Use Caution/Monitor.nalbuphine and perphenazine both increase sedation. Use Caution/Monitor.naratriptannaratriptan and amitriptyline both increase serotonin levels. Modify Therapy/Monitor Closely.naratriptan, 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).nebivololperphenazine will increase the level or effect of nebivolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.nefazodonenefazodone will increase the level or effect of amitriptyline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nefazodone will increase the level or effect of amitriptyline by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.nefopamnefopam, amitriptyline. Mechanism: unspecified interaction mechanism. Use Caution/Monitor. Use combination with caution.nelfinavirnelfinavir will increase the level or effect of amitriptyline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.neostigmineneostigmine increases and amitriptyline decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.nicardipinenicardipine will increase the level or effect of amitriptyline by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.nifedipinenifedipine will decrease the level or effect of amitriptyline by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.norepinephrineperphenazine, norepinephrine. 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.amitriptyline increases and norepinephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.perphenazine increases and norepinephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.amitriptyline increases effects of norepinephrine by unknown mechanism. Use Caution/Monitor.nortriptylineamitriptyline and nortriptyline both increase sedation. Use Caution/Monitor.perphenazine will increase the level or effect of nortriptyline by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.amitriptyline and nortriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.perphenazine and nortriptyline both increase sedation. Use Caution/Monitor.ofloxacinamitriptyline and ofloxacin both increase QTc interval. Modify Therapy/Monitor Closely.perphenazine and ofloxacin both increase QTc interval. Modify Therapy/Monitor Closely.olanzapineolanzapine and perphenazine both increase sedation. Use Caution/Monitor.olanzapine and amitriptyline both increase QTc interval. Use Caution/Monitor.olanzapine and perphenazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.olanzapine and amitriptyline both increase sedation. Use Caution/Monitor.olanzapine and perphenazine both increase QTc interval. Use Caution/Monitor.oliceridineamitriptyline, oliceridine. Either increases effects of the other by serotonin levels. Modify Therapy/Monitor Closely.oliceridine, perphenazine. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. 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).amitriptyline increases toxicity of oliceridine by Other (see comment). Modify Therapy/Monitor Closely. 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.olodaterol inhaledamitriptyline and olodaterol inhaled both increase QTc interval. Use Caution/Monitor. TCAs prolong the QTc interval and may potentiate the effects of beta2 agonists on the cardiovascular system; increased risk of ventricular arrhythmiasperphenazine and olodaterol inhaled both increase QTc interval. Use Caution/Monitor. Drugs that prolong the QTc interval and may potentiate the effects of beta2 agonists on the cardiovascular system; increased risk of ventricular arrhythmiasonabotulinumtoxinAonabotulinumtoxinA and amitriptyline both decrease cholinergic effects/transmission. Modify Therapy/Monitor Closely.onabotulinumtoxinA decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.onabotulinumtoxinA decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.perphenazine increases effects of onabotulinumtoxinA by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.opium tinctureopium tincture and perphenazine both increase sedation. Use Caution/Monitor.opium tincture and amitriptyline both increase sedation. Use Caution/Monitor.orphenadrineamitriptyline and orphenadrine both decrease cholinergic effects/transmission. Use Caution/Monitor.orphenadrine and perphenazine both increase sedation. Use Caution/Monitor.orphenadrine and amitriptyline both increase sedation. Use Caution/Monitor.osilodrostatosilodrostat and amitriptyline both increase QTc interval. Use Caution/Monitor.osimertinibosimertinib and perphenazine both increase QTc interval. Use Caution/Monitor. Conduct periodic monitoring with ECGs and electrolytes in patients taking drugs known to prolong the QTc interval.osimertinibosimertinib and amitriptyline both increase QTc interval. Use Caution/Monitor. Conduct periodic monitoring with ECGs and electrolytes in patients taking drugs known to prolong the QTc interval.oxaliplatinoxaliplatin will increase the level or effect of amitriptyline by Other (see comment). Use Caution/Monitor. Monitor for ECG changes if therapy is initiated in patients with drugs known to prolong QT interval.oxaliplatin and perphenazine both increase QTc interval. Use Caution/Monitor.oxazepamoxazepam and perphenazine both increase sedation. Use Caution/Monitor.oxazepam and amitriptyline both increase sedation. Use Caution/Monitor.oxybutyninoxybutynin decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.oxybutynin decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.perphenazine increases effects of oxybutynin by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.oxybutynin and amitriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.oxybutynin topicaloxybutynin topical decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.perphenazine increases effects of oxybutynin topical by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.oxybutynin topical and amitriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.oxybutynin topical decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.oxybutynin transdermaloxybutynin transdermal decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.oxybutynin transdermal decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.perphenazine increases effects of oxybutynin transdermal by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.oxybutynin transdermal and amitriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.oxycodoneoxycodone and perphenazine both increase sedation. Use Caution/Monitor.perphenazine will increase the level or effect of oxycodone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.oxycodone and amitriptyline both increase sedation. Use Caution/Monitor.oxymetazoline intranasalamitriptyline increases effects of oxymetazoline intranasal by pharmacodynamic synergism. Use Caution/Monitor. TCAs inhibit norepinephrine uptake in adrenergic neurons, thereby increasing synaptic norepinephrine levels. Coadministration with alpha1 agonists may cause increased adrenergic receptor stimulation. When oxymetazoline is combined with intranasal tetracaine for dental anesthesia, avoid or use alternant anesthetic in patients taking TCAs.oxymorphoneperphenazine will increase the level or effect of oxymorphone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.oxymorphone and perphenazine both increase sedation. Use Caution/Monitor.oxymorphoneoxymorphone and amitriptyline both increase sedation. Use Caution/Monitor.ozanimodozanimod and perphenazine both increase QTc interval. Modify Therapy/Monitor Closely. The potential additive effects on heart rate, treatment with ozanimod should generally not be initiated in patients who are concurrently treated with QT prolonging drugs with known arrhythmogenic properties.ozanimod and amitriptyline both increase QTc interval. Modify Therapy/Monitor Closely. The potential additive effects on heart rate, treatment with ozanimod should generally not be initiated in patients who are concurrently treated with QT prolonging drugs with known arrhythmogenic properties.paliperidoneamitriptyline and paliperidone both increase QTc interval. Modify Therapy/Monitor Closely.paliperidone and perphenazine both increase sedation. Use Caution/Monitor.paliperidone and perphenazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.paliperidone and amitriptyline both increase sedation. Use Caution/Monitor.perphenazine and paliperidone both increase QTc interval. Modify Therapy/Monitor Closely.pancuroniumpancuronium and amitriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.perphenazine increases effects of pancuronium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.pancuronium decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.pancuronium decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.panobinostatpanobinostat will increase the level or effect of perphenazine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Panobinostat can increase the levels and effects of sensitive CYP2D6 substrates or those with a narrow therapeutic index CYP2D6.papaveretumpapaveretum and amitriptyline both increase sedation. Use Caution/Monitor.papaveretumpapaveretum and perphenazine both increase sedation. Use Caution/Monitor.papaverineperphenazine and papaverine both increase sedation. Use Caution/Monitor.amitriptyline and papaverine both increase sedation. Use Caution/Monitor.paroxetineparoxetine, 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).amitriptyline and paroxetine both increase QTc interval. Modify Therapy/Monitor Closely.pasireotideamitriptyline and pasireotide both increase QTc interval. Modify Therapy/Monitor Closely.perphenazine and pasireotide both increase QTc interval. Modify Therapy/Monitor Closely.pazopanibperphenazine and pazopanib both increase QTc interval. Use Caution/Monitor.amitriptyline and pazopanib both increase QTc interval. Use Caution/Monitor.peginterferon alfa 2bpeginterferon alfa 2b, perphenazine. Other (see comment). Use Caution/Monitor. Comment: When patients are administered peginterferon alpha-2b with CYP2D6 substrates, the therapeutic effect of these drugs may be altered. Peginterferon alpha-2b may increase or decrease levels of CYP2D6 substrate.peginterferon alfa 2b, amitriptyline. Other (see comment). Use Caution/Monitor. Comment: When patients are administered peginterferon alpha-2b with CYP2D6 substrates, the therapeutic effect of these drugs may be altered. Peginterferon alpha-2b may increase or decrease levels of CYP2D6 substrate.pentazocineamitriptyline and pentazocine both increase serotonin levels. Modify Therapy/Monitor Closely.pentazocine and perphenazine both increase sedation. Use Caution/Monitor.pentazocine and amitriptyline both increase sedation. Use Caution/Monitor.pentobarbitalpentobarbital and perphenazine both increase sedation. Use Caution/Monitor.pentobarbital will decrease the level or effect of amitriptyline by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.pentobarbital will decrease the level or effect of amitriptyline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.pentobarbital and amitriptyline both increase sedation. Use Caution/Monitor.perphenazineperphenazine and amitriptyline both increase sedation. Use Caution/Monitor.phendimetrazineperphenazine increases and phendimetrazine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.perphenazine, phendimetrazine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden