Elderly patients with dementia-related psychosis treated with antipsychotic drugs are at an increased risk of death. Analyses of 17 placebo-controlled trials (modal duration of 10 weeks), largely in patients taking atypical antipsychotic drugs, revealed a risk of death in drug-treated patients of between 1.6 and 1.7 times the risk of death in placebo-treated patients. Over the course of a typical 10-week controlled trial, the rate of death in drug-treated patients was approximately 4.5% compared with a rate of approximately 2.6% in the placebo group. Although the causes of death were varied, most of the deaths appeared to be either cardiovascular (eg, heart failure, sudden death) or infectious (eg, pneumonia) in nature. Observational studies suggest that, similar to atypical antipsychotic drugs, treatment with conventional antipsychotic drugs may increase mortality. The extent to which the findings of increased mortality in observational studies may be attributed to the antipsychotic drug as opposed to some characteristic(s) of the patients is not clear. Perphenazine is not approved for the treatment of patients with dementia-related psychosis.
Nausea/vomiting: Oral: 8 to 16 mg/day in divided doses; occasionally, doses as high as 24 mg/day may be necessary. Reduce dose as soon as possible to minimum effective dosage.
Schizophrenia: Oral: Initial: 8 to 16 mg/day in 2 to 4 divided doses; titrate based on response and tolerability. Doses as high as 32 mg/day in divided doses have been shown to have similar efficacy and tolerability compared to some second-generation antipsychotics; doses as high as 64 mg/day in divided doses may be appropriate in some situations (Høyberg 1993; Lieberman 2005; WFSBP [Hasan 2013]; manufacturer’s labeling).
Discontinuation of therapy: In the treatment of chronic psychiatric disease switching therapy rather than discontinuation is generally advised if side effects are intolerable or treatment is not effective. If patient insists on stopping treatment, gradual dose reduction (ie, over several weeks to months) is advised to detect a re-emergence of symptoms and to avoid withdrawal reactions (eg, agitation, alternating feelings of warmth and chill, anxiety, diaphoresis, dyskinesias, GI symptoms, insomnia, irritability, myalgia, paresthesia, psychosis, restlessness, rhinorrhea, tremor, vertigo) unless discontinuation is due to significant adverse effects. Monitor closely to allow for detection of prodromal symptoms of disease recurrence.
Switching antipsychotics: An optimal universal strategy for switching antipsychotic drugs has not been established. Strategies include: Cross-titration (gradually discontinuing the first antipsychotic while gradually increasing the new antipsychotic) and abrupt change (abruptly discontinuing the first antipsychotic and either increasing the new antipsychotic gradually or starting it at a treatment dose). In patients with schizophrenia at high risk of relapse, the current medication may be maintained at full dose as the new medication is increased (ie, overlap); once the new medication is at therapeutic dose, the first medication is gradually decreased and discontinued over 1 to 2 weeks (Cerovecki 2013; Remington 2005; Takeuchi 2017). Based upon clinical experience, some experts generally prefer cross-titration and overlap approaches rather than abrupt change (Stroup 2022).
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
There are no dosage adjustments provided in manufacturer's labeling; use with caution.
There are no dosage adjustment provided in manufacturer's labeling; contraindicated in patients with liver damage.
(For additional information see "Perphenazine: Pediatric drug information")
Schizophrenia: Note: In the management of pediatric patients with schizophrenia, use has generally been replaced by second-generation antipsychotics (AACAP [McClellan 2013]). Dosage should be individualized; use lowest effective dose and shortest effective duration; periodically reassess the need for continued treatment.
Children ≥12 years and Adolescents: Oral: Initial: 8 to 16 mg/day in divided doses 2 to 4 times daily; titrate based on response and tolerability. Doses as high as 32 mg/day have been shown to have similar efficacy and tolerability compared to some second-generation antipsychotics; doses as high as 64 mg/day may be appropriate in some situations based on experience in adult patients (APA [Lehman 2004]; Lieberman 2005).
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
There are no dosage adjustments provided in manufacturer's labeling; use with caution.
There are no dosage adjustment provided in manufacturer's labeling; contraindicated in patients with liver damage
Refer to adult dosing. Dosages in the lower range of recommended adult dosing are generally sufficient with late-onset schizophrenia or psychosis. Titrate dosage slowly and monitor carefully (Howard 2000).
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Tablet, Oral:
Generic: 2 mg, 4 mg, 8 mg, 16 mg
Yes
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Tablet, Oral:
Generic: 2 mg, 4 mg, 8 mg, 16 mg
Oral: May be administered without regard to meals
Nausea/vomiting: Control of severe nausea and vomiting in adults
Schizophrenia: Treatment of schizophrenia
Trilafon may be confused with Tri-Levlen
Beers Criteria: Antipsychotics are identified in the Beers Criteria as potentially inappropriate medications to be avoided in patients 65 years and older due to an increased risk of cerebrovascular accidents (stroke) and a greater rate of cognitive decline and mortality in patients with dementia. Antipsychotics may be appropriate for schizophrenia, bipolar disorder, other mental health conditions or short-term use as antiemetic during chemotherapy but should be given in the lowest effective dose for the shortest duration possible. In addition, antipsychotics should be used with caution in older adults due to their potential to cause or exacerbate syndrome of inappropriate antidiuretic hormone secretion (SIADH) or hyponatremia; monitor sodium closely with initiation or dosage adjustments in older adults (Beers Criteria [AGS 2019]).
KIDs List: Dopamine antagonists, when used in pediatric patients <18 years of age, are identified on the Key Potentially Inappropriate Drugs in Pediatrics (KIDs) list; use should be avoided in infants and used with caution in children and adolescents due to risk of acute dystonia (dyskinesia) (strong recommendation; moderate quality of evidence) (PPA [Meyers 2020]).
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.
Frequency not defined.
Cardiovascular: Bradycardia, ECG changes, hypertension, hypotension, orthostatic hypotension, peripheral edema, tachycardia
Central nervous system: Bizarre dream, catatonic-like state, cerebral edema, confusion (nocturnal), disruption of body temperature regulation, dizziness, drowsiness, extrapyramidal reaction (akathisia, dystonia, Parkinsonian-like syndrome, tardive dyskinesia), headache, hyperactivity, hyperpyrexia, insomnia, lethargy, myasthenia, neuroleptic malignant syndrome (NMS), paradoxical excitation, paranoia, restlessness, seizure
Dermatologic: Diaphoresis, pallor, skin discoloration (blue-gray), skin photosensitivity
Endocrine & metabolic: Amenorrhea, change in libido, galactorrhea, glycosuria, gynecomastia, hyperglycemia, hypoglycemia, menstrual disease, SIADH (syndrome of inappropriate antidiuretic hormone secretion), weight gain
Gastrointestinal: Anorexia, constipation, diarrhea, fecal impaction, increased appetite, nausea, obstipation, paralytic ileus, salivation, vomiting, xerostomia
Genitourinary: Bladder paralysis, breast hypertrophy, ejaculatory disorder, lactation, urinary incontinence, urinary retention
Hematologic & oncologic: Agranulocytosis, eosinophilia, hemolytic anemia, immune thrombocytopenia (formerly known as immune thrombocytopenic purpura), leukopenia, pancytopenia
Hepatic: Hepatotoxicity, jaundice
Hypersensitivity: Hypersensitivity reaction
Neuromuscular & skeletal: Lupus-like syndrome
Ophthalmic: Blurred vision, corneal changes, epithelial keratopathy, glaucoma, lens disease, miosis, mydriasis, photophobia, retinitis pigmentosa
Renal: Polyuria
Respiratory: Nasal congestion
<1%, postmarketing, and/or case reports: Parotid gland enlargement
Hypersensitivity to perphenazine or any component of the formulation; severe CNS depression (comatose or patients receiving large doses of CNS depressants); subcortical brain damage with or without hypothalamic damage (known or suspected); bone marrow suppression; blood dyscrasias; liver damage.
Documentation of allergenic cross-reactivity for phenothiazines is limited. However, because of similarities in chemical structure and/or pharmacologic actions, the possibility of cross-sensitivity cannot be ruled out with certainty.
Concerns related to adverse effects:
• Altered cardiac conduction: May alter cardiac conduction; life-threatening arrhythmias have occurred with therapeutic doses of phenothiazines (Haddad 2002; Stollberger 2005).
• Anticholinergic effects: May cause anticholinergic effects (constipation, xerostomia, blurred vision, urinary retention); use with caution in patients with decreased gastrointestinal motility, paralytic ileus, urinary retention, BPH, xerostomia, or visual problems. Relative to other neuroleptics, perphenazine has a low potency of cholinergic blockade.
• Antiemetic effects: May mask toxicity of other drugs or conditions (eg, intestinal obstruction, Reye syndrome, brain tumor) due to antiemetic effects.
• Blood dyscrasias: Leukopenia, neutropenia, and agranulocytosis (sometimes fatal) have been reported in clinical trials and postmarketing reports with antipsychotic use; presence of risk factors (eg, preexisting low WBC or history of drug-induced leuko-/neutropenia) should prompt periodic blood count assessment. Discontinue therapy at first signs of blood dyscrasias or if absolute neutrophil count <1,000/mm3.
• CNS depression: May cause CNS depression, which may impair physical or mental abilities; patients must be cautioned about performing tasks that require mental alertness (eg, operating machinery, driving).
• Esophageal dysmotility/Aspiration: Antipsychotic use has been associated with esophageal dysmotility and aspiration; risks increase with age. Use with caution in patients at risk for aspiration pneumonia (eg, Alzheimer disease), particularly in patients >75 years (Herzig 2017; Maddalena 2004).
• Extrapyramidal symptoms: May cause extrapyramidal symptoms (EPS), including pseudoparkinsonism, acute dystonic reactions, akathisia, and tardive dyskinesia. Risk of dystonia (and possibly other EPS) may be greater with increased doses, use of conventional antipsychotics, males, and younger patients. Factors associated with greater vulnerability to tardive dyskinesia include older in age, female gender combined with postmenopausal status, Parkinson disease, pseudoparkinsonism symptoms, affective disorders (particularly major depressive disorder), concurrent medical diseases such as diabetes, previous brain damage, alcoholism, poor treatment response, and use of high doses of antipsychotics (APA [Keepers 2020]; Soares-Weiser 2007). Consider therapy discontinuation with signs/symptoms of tardive dyskinesia.
• Falls: May increase the risk for falls due to somnolence, orthostatic hypotension, or motor and sensory instability.
• Hyperprolactinemia: Use associated with increased prolactin levels; clinical significance of hyperprolactinemia in patients with breast cancer or other prolactin-dependent tumors is unknown.
• Neuroleptic malignant syndrome: May be associated with neuroleptic malignant syndrome (NMS); monitor for mental status changes, fever, muscle rigidity, and/or autonomic instability. Following recovery from NMS, reintroduction of drug therapy should be carefully considered; if an antipsychotic agent is resumed, monitor closely for NMS.
• Ocular effects: May cause pigmentary retinopathy, and lenticular and corneal deposits, particularly with prolonged therapy.
• Orthostatic hypotension: May cause orthostatic hypotension; use with caution in patients at risk of this effect or in those who would not tolerate transient hypotensive episodes (cerebrovascular disease, cardiovascular disease, hypovolemia, or concurrent medication use which may predispose to hypotension/bradycardia).
• Photosensitivity: May cause photosensitization; avoid prolonged exposure to sunlight.
• Temperature regulation: Impaired core body temperature regulation may occur; caution with strenuous exercise, heat exposure, dehydration, and concomitant medication possessing anticholinergic effects.
Disease-related concerns:
• Cardiovascular disease: Use with caution in patients with cardiovascular disease.
• Dementia: [US Boxed Warning]: Elderly patients with dementia-related psychosis treated with antipsychotics are at an increased risk of death compared to placebo. Most deaths appeared to be either cardiovascular (eg, heart failure, sudden death) or infectious (eg, pneumonia) in nature. Use with caution in patients with Lewy body dementia or Parkinson disease dementia due to greater risk of adverse effects, increased sensitivity to extrapyramidal effects, and association with irreversible cognitive decompensation or death. The APA recommends giving preference to second generation antipsychotics over first generation antipsychotics in elderly patients with dementia-related psychosis due to a potentially greater risk of harm relative to second generation antipsychotics (APA [Reus 2016]). Perphenazine is not approved for the treatment of dementia-related psychosis.
• Depression: Use with caution in patients with depression; possibility of increased risk of suicide; limit quantities of drug available until significant remission observed.
• Hepatic impairment: Monitor hepatic function during use; discontinue if abnormalities occur; contraindicated in patients with liver damage.
• Renal impairment: Use with caution in patients with renal impairment. Monitor renal function during therapy; discontinue if BUN abnormalities occur.
• Respiratory disease: Use with caution in patients with respiratory disease.
• Seizure disorder: Use with caution in patients at risk of seizures, including those with a history of seizures; first-generation antipsychotics may lower the seizure threshold (APA [Keepers 2020]).
Special populations:
• Poor metabolizers: Use with caution in patients with reduced functional alleles of CYP2D6. Poor metabolizers may have higher plasma concentrations at usual doses, increasing risk for adverse reactions.
Other warnings/precautions:
• Discontinuation of therapy: When discontinuing antipsychotic therapy, gradually taper antipsychotics to avoid physical withdrawal symptoms and rebound symptoms (APA [Keepers 2020]; WFSBP [Hasan 2012]). Withdrawal symptoms may include agitation, alternating feelings of warmth and cold, anxiety, diaphoresis, dyskinesia, GI symptoms, insomnia, irritability, myalgia, paresthesia, psychosis, restlessness, rhinorrhea, tremor and vertigo (Lambert 2007; Moncrieff 2020). The risk of withdrawal symptoms is highest following abrupt discontinuation of highly anticholinergic or dopaminergic antipsychotics (Cerovecki 2013). Patients with chronic symptoms, repeated relapses, and clear diagnostic features of schizophrenia are at risk for poor outcomes if medications are discontinued (APA [Keepers 2020]).
Risk of dystonia is increased with the use of high potency and higher doses of conventional antipsychotics and in males and younger patients. Use with caution in children and adolescents; adverse effects due to elevated prolactin levels have been observed; long-term effects on growth or sexual maturation have not been evaluated. Similar to adult experience, the American Academy of Child and Adolescent Psychiatry (AACAP) guidelines recommend gradually tapering antipsychotics to avoid withdrawal symptoms and minimize the risk of relapse (AACAP [McClellan 2007]).
Substrate of CYP1A2 (minor), CYP2C19 (minor), CYP2C9 (minor), CYP2D6 (major), CYP3A4 (minor); Note: Assignment of Major/Minor substrate status based on clinically relevant drug interaction potential
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the Lexicomp drug interactions program by clicking on the “Launch drug interactions program” link above.
Acetylcholinesterase Inhibitors: May diminish the therapeutic effect of Anticholinergic Agents. Anticholinergic Agents may diminish the therapeutic effect of Acetylcholinesterase Inhibitors. Risk C: Monitor therapy
Acetylcholinesterase Inhibitors (Central): May enhance the neurotoxic (central) effect of Antipsychotic Agents. Severe extrapyramidal symptoms have occurred in some patients. Risk C: Monitor therapy
Aclidinium: May enhance the anticholinergic effect of Anticholinergic Agents. Risk X: Avoid combination
Agents With Seizure Threshold Lowering Potential: May enhance the adverse/toxic effect of Antipsychotic Agents. Specifically, the risk of seizures may be increased. Risk C: Monitor therapy
Ajmaline: May increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Risk C: Monitor therapy
Alcohol (Ethyl): CNS Depressants may enhance the CNS depressant effect of Alcohol (Ethyl). Risk C: Monitor therapy
Alizapride: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Amifampridine: Agents With Seizure Threshold Lowering Potential may enhance the neuroexcitatory and/or seizure-potentiating effect of Amifampridine. Risk C: Monitor therapy
Aminolevulinic Acid (Systemic): Photosensitizing Agents may enhance the photosensitizing effect of Aminolevulinic Acid (Systemic). Risk X: Avoid combination
Aminolevulinic Acid (Topical): Photosensitizing Agents may enhance the photosensitizing effect of Aminolevulinic Acid (Topical). Risk C: Monitor therapy
Amisulpride (Oral): May enhance the adverse/toxic effect of Antipsychotic Agents. Specifically, the risk of neuroleptic malignant syndrome or increased QTc interval may be increased. Risk C: Monitor therapy
Amphetamines: Antipsychotic Agents may enhance the adverse/toxic effect of Amphetamines. Antipsychotic Agents may diminish the stimulatory effect of Amphetamines. Risk C: Monitor therapy
Antacids: May decrease the absorption of Antipsychotic Agents (Phenothiazines). Risk C: Monitor therapy
Anticholinergic Agents: May enhance the adverse/toxic effect of other Anticholinergic Agents. Risk C: Monitor therapy
Anti-Parkinson Agents (Dopamine Agonist): May diminish the therapeutic effect of Antipsychotic Agents (First Generation [Typical]). Antipsychotic Agents (First Generation [Typical]) may diminish the therapeutic effect of Anti-Parkinson Agents (Dopamine Agonist). Management: Avoid concomitant therapy if possible. If antipsychotic use is necessary, consider using atypical antipsychotics such as clozapine, quetiapine, or ziprasidone at lower initial doses, or a non-dopamine antagonist (eg, pimavanserin). Risk D: Consider therapy modification
Antipsychotic Agents: Agents With Seizure Threshold Lowering Potential may enhance the adverse/toxic effect of Antipsychotic Agents. Specifically, the risk of seizures may be increased. Risk C: Monitor therapy
Artemether and Lumefantrine: May increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Risk C: Monitor therapy
Azelastine (Nasal): May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Beta-Blockers: Antipsychotic Agents (Phenothiazines) may enhance the hypotensive effect of Beta-Blockers. Beta-Blockers may decrease the metabolism of Antipsychotic Agents (Phenothiazines). Antipsychotic Agents (Phenothiazines) may decrease the metabolism of Beta-Blockers. Risk C: Monitor therapy
Blonanserin: CNS Depressants may enhance the CNS depressant effect of Blonanserin. Management: Use caution if coadministering blonanserin and CNS depressants; dose reduction of the other CNS depressant may be required. Strong CNS depressants should not be coadministered with blonanserin. Risk D: Consider therapy modification
Botulinum Toxin-Containing Products: May enhance the anticholinergic effect of Anticholinergic Agents. Risk C: Monitor therapy
Brexanolone: CNS Depressants may enhance the CNS depressant effect of Brexanolone. Risk C: Monitor therapy
Brimonidine (Topical): May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Bromopride: May enhance the adverse/toxic effect of Antipsychotic Agents. Risk X: Avoid combination
Bromperidol: May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Buprenorphine: CNS Depressants may enhance the CNS depressant effect of Buprenorphine. Management: Consider reduced doses of other CNS depressants, and avoiding such drugs in patients at high risk of buprenorphine overuse/self-injection. Initiate buprenorphine at lower doses in patients already receiving CNS depressants. Risk D: Consider therapy modification
BuPROPion: May enhance the neuroexcitatory and/or seizure-potentiating effect of Agents With Seizure Threshold Lowering Potential. Risk C: Monitor therapy
Cabergoline: May diminish the therapeutic effect of Antipsychotic Agents. Risk X: Avoid combination
Cannabinoid-Containing Products: Anticholinergic Agents may enhance the tachycardic effect of Cannabinoid-Containing Products. Risk C: Monitor therapy
Cannabinoid-Containing Products: CNS Depressants may enhance the CNS depressant effect of Cannabinoid-Containing Products. Risk C: Monitor therapy
Chloral Betaine: May enhance the adverse/toxic effect of Anticholinergic Agents. Risk C: Monitor therapy
Chlormethiazole: May enhance the CNS depressant effect of CNS Depressants. Management: Monitor closely for evidence of excessive CNS depression. The chlormethiazole labeling states that an appropriately reduced dose should be used if such a combination must be used. Risk D: Consider therapy modification
Chlorphenesin Carbamate: May enhance the adverse/toxic effect of CNS Depressants. Risk C: Monitor therapy
Cimetropium: Anticholinergic Agents may enhance the anticholinergic effect of Cimetropium. Risk X: Avoid combination
CloZAPine: Anticholinergic Agents may enhance the constipating effect of CloZAPine. Management: Consider alternatives to this combination whenever possible. If combined, monitor closely for signs and symptoms of gastrointestinal hypomotility and consider prophylactic laxative treatment. Risk D: Consider therapy modification
CNS Depressants: May enhance the adverse/toxic effect of other CNS Depressants. Risk C: Monitor therapy
CYP2D6 Inhibitors (Moderate): May increase the serum concentration of Perphenazine. Risk C: Monitor therapy
CYP2D6 Inhibitors (Strong): May increase the serum concentration of Perphenazine. Risk C: Monitor therapy
Daridorexant: May enhance the CNS depressant effect of CNS Depressants. Management: Dose reduction of daridorexant and/or any other CNS depressant may be necessary. Use of daridorexant with alcohol is not recommended, and the use of daridorexant with any other drug to treat insomnia is not recommended. Risk D: Consider therapy modification
Deutetrabenazine: May enhance the adverse/toxic effect of Antipsychotic Agents. Specifically, the risk for akathisia, parkinsonism, or neuroleptic malignant syndrome may be increased. Risk C: Monitor therapy
DexmedeTOMIDine: CNS Depressants may enhance the CNS depressant effect of DexmedeTOMIDine. Management: Monitor for increased CNS depression during coadministration of dexmedetomidine and CNS depressants, and consider dose reductions of either agent to avoid excessive CNS depression. Risk D: Consider therapy modification
Dexmethylphenidate-Methylphenidate: Antipsychotic Agents may enhance the adverse/toxic effect of Dexmethylphenidate-Methylphenidate. Dexmethylphenidate-Methylphenidate may enhance the adverse/toxic effect of Antipsychotic Agents. Specifically, the risk of extrapyramidal symptoms may be increased when these agents are combined. Risk C: Monitor therapy
Difelikefalin: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Dimethindene (Topical): May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Doxylamine: May enhance the CNS depressant effect of CNS Depressants. Management: The manufacturer of Diclegis (doxylamine/pyridoxine), intended for use in pregnancy, specifically states that use with other CNS depressants is not recommended. Risk C: Monitor therapy
Droperidol: May enhance the CNS depressant effect of CNS Depressants. Management: Consider dose reductions of droperidol or of other CNS agents (eg, opioids, barbiturates) with concomitant use. Risk D: Consider therapy modification
Eluxadoline: Anticholinergic Agents may enhance the constipating effect of Eluxadoline. Risk X: Avoid combination
Esketamine: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Flunarizine: CNS Depressants may enhance the CNS depressant effect of Flunarizine. Risk X: Avoid combination
Flunitrazepam: CNS Depressants may enhance the CNS depressant effect of Flunitrazepam. Management: Reduce the dose of CNS depressants when combined with flunitrazepam and monitor patients for evidence of CNS depression (eg, sedation, respiratory depression). Use non-CNS depressant alternatives when available. Risk D: Consider therapy modification
Gastrointestinal Agents (Prokinetic): Anticholinergic Agents may diminish the therapeutic effect of Gastrointestinal Agents (Prokinetic). Risk C: Monitor therapy
Glucagon: Anticholinergic Agents may enhance the adverse/toxic effect of Glucagon. Specifically, the risk of gastrointestinal adverse effects may be increased. Risk C: Monitor therapy
Glycopyrrolate (Oral Inhalation): Anticholinergic Agents may enhance the anticholinergic effect of Glycopyrrolate (Oral Inhalation). Risk X: Avoid combination
Glycopyrronium (Topical): May enhance the anticholinergic effect of Anticholinergic Agents. Risk X: Avoid combination
Guanethidine: Antipsychotic Agents may diminish the therapeutic effect of Guanethidine. Risk C: Monitor therapy
HydrOXYzine: May enhance the CNS depressant effect of CNS Depressants. Management: Consider a decrease in the CNS depressant dose, as appropriate, when used together with hydroxyzine. Increase monitoring of signs/symptoms of CNS depression in any patient receiving hydroxyzine together with another CNS depressant. Risk D: Consider therapy modification
Iohexol: Agents With Seizure Threshold Lowering Potential may enhance the adverse/toxic effect of Iohexol. Specifically, the risk for seizures may be increased. Management: Discontinue agents that may lower the seizure threshold 48 hours prior to intrathecal use of iohexol. Wait at least 24 hours after the procedure to resume such agents. In nonelective procedures, consider use of prophylactic antiseizure drugs. Risk D: Consider therapy modification
Iomeprol: Agents With Seizure Threshold Lowering Potential may enhance the adverse/toxic effect of Iomeprol. Specifically, the risk for seizures may be increased. Management: Discontinue agents that may lower the seizure threshold 48 hours prior to intrathecal use of iomeprol. Wait at least 24 hours after the procedure to resume such agents. In nonelective procedures, consider use of prophylactic antiseizure drugs. Risk D: Consider therapy modification
Iopamidol: Agents With Seizure Threshold Lowering Potential may enhance the adverse/toxic effect of Iopamidol. Specifically, the risk for seizures may be increased. Management: Discontinue agents that may lower the seizure threshold 48 hours prior to intrathecal use of iopamidol. Wait at least 24 hours after the procedure to resume such agents. In nonelective procedures, consider use of prophylactic antiseizure drugs. Risk D: Consider therapy modification
Ipratropium (Oral Inhalation): May enhance the anticholinergic effect of Anticholinergic Agents. Risk X: Avoid combination
Itopride: Anticholinergic Agents may diminish the therapeutic effect of Itopride. Risk C: Monitor therapy
Kava Kava: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Kratom: May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Lemborexant: May enhance the CNS depressant effect of CNS Depressants. Management: Dosage adjustments of lemborexant and of concomitant CNS depressants may be necessary when administered together because of potentially additive CNS depressant effects. Close monitoring for CNS depressant effects is necessary. Risk D: Consider therapy modification
Levosulpiride: Anticholinergic Agents may diminish the therapeutic effect of Levosulpiride. Risk X: Avoid combination
Lithium: May enhance the neurotoxic effect of Antipsychotic Agents. Lithium may decrease the serum concentration of Antipsychotic Agents. Specifically noted with chlorpromazine. Risk C: Monitor therapy
Lofexidine: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Magnesium Sulfate: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Mequitazine: Antipsychotic Agents may enhance the arrhythmogenic effect of Mequitazine. Management: Consider alternatives to one of these agents when possible. While this combination is not specifically contraindicated, mequitazine labeling describes this combination as discouraged. Risk D: Consider therapy modification
Methotrimeprazine: CNS Depressants may enhance the CNS depressant effect of Methotrimeprazine. Methotrimeprazine may enhance the CNS depressant effect of CNS Depressants. Management: Reduce the usual dose of CNS depressants by 50% if starting methotrimeprazine until the dose of methotrimeprazine is stable. Monitor patient closely for evidence of CNS depression. Risk D: Consider therapy modification
Methoxsalen (Systemic): Photosensitizing Agents may enhance the photosensitizing effect of Methoxsalen (Systemic). Risk C: Monitor therapy
Metoclopramide: May enhance the adverse/toxic effect of Antipsychotic Agents. Risk X: Avoid combination
MetyroSINE: CNS Depressants may enhance the sedative effect of MetyroSINE. Risk C: Monitor therapy
MetyroSINE: May enhance the adverse/toxic effect of Antipsychotic Agents. Risk C: Monitor therapy
Mianserin: May enhance the anticholinergic effect of Anticholinergic Agents. Risk C: Monitor therapy
Minocycline (Systemic): May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Mirabegron: Anticholinergic Agents may enhance the adverse/toxic effect of Mirabegron. Risk C: Monitor therapy
Nitroglycerin: Anticholinergic Agents may decrease the absorption of Nitroglycerin. Specifically, anticholinergic agents may decrease the dissolution of sublingual nitroglycerin tablets, possibly impairing or slowing nitroglycerin absorption. Risk C: Monitor therapy
Olopatadine (Nasal): May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Opioid Agonists: CNS Depressants may enhance the CNS depressant effect of Opioid Agonists. Management: Avoid concomitant use of opioid agonists and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Risk D: Consider therapy modification
Orphenadrine: CNS Depressants may enhance the CNS depressant effect of Orphenadrine. Risk X: Avoid combination
Oxatomide: May enhance the anticholinergic effect of Anticholinergic Agents. Risk X: Avoid combination
Oxomemazine: May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Oxybate Salt Products: CNS Depressants may enhance the CNS depressant effect of Oxybate Salt Products. Management: Consider alternatives to this combination when possible. If combined, dose reduction or discontinuation of one or more CNS depressants (including the oxybate salt product) should be considered. Interrupt oxybate salt treatment during short-term opioid use Risk D: Consider therapy modification
OxyCODONE: CNS Depressants may enhance the CNS depressant effect of OxyCODONE. Management: Avoid concomitant use of oxycodone and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Risk D: Consider therapy modification
Paraldehyde: CNS Depressants may enhance the CNS depressant effect of Paraldehyde. Risk X: Avoid combination
Peginterferon Alfa-2b: May decrease the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Peginterferon Alfa-2b may increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Risk C: Monitor therapy
Perampanel: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Piribedil: Antipsychotic Agents may diminish the therapeutic effect of Piribedil. Piribedil may diminish the therapeutic effect of Antipsychotic Agents. Management: Use of piribedil with antiemetic neuroleptics is contraindicated, and use with antipsychotic neuroleptics, except for clozapine, is not recommended. Risk X: Avoid combination
Porfimer: Photosensitizing Agents may enhance the photosensitizing effect of Porfimer. Risk C: Monitor therapy
Potassium Chloride: Anticholinergic Agents may enhance the ulcerogenic effect of Potassium Chloride. Management: Patients on drugs with substantial anticholinergic effects should avoid using any solid oral dosage form of potassium chloride. Risk X: Avoid combination
Potassium Citrate: Anticholinergic Agents may enhance the ulcerogenic effect of Potassium Citrate. Risk X: Avoid combination
Pramlintide: May enhance the anticholinergic effect of Anticholinergic Agents. These effects are specific to the GI tract. Risk X: Avoid combination
Procarbazine: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Quinagolide: Antipsychotic Agents may diminish the therapeutic effect of Quinagolide. Risk C: Monitor therapy
Ramosetron: Anticholinergic Agents may enhance the constipating effect of Ramosetron. Risk C: Monitor therapy
Revefenacin: Anticholinergic Agents may enhance the anticholinergic effect of Revefenacin. Risk X: Avoid combination
Ropeginterferon Alfa-2b: CNS Depressants may enhance the adverse/toxic effect of Ropeginterferon Alfa-2b. Specifically, the risk of neuropsychiatric adverse effects may be increased. Management: Avoid coadministration of ropeginterferon alfa-2b and other CNS depressants. If this combination cannot be avoided, monitor patients for neuropsychiatric adverse effects (eg, depression, suicidal ideation, aggression, mania). Risk D: Consider therapy modification
Rufinamide: May enhance the adverse/toxic effect of CNS Depressants. Specifically, sleepiness and dizziness may be enhanced. Risk C: Monitor therapy
Saquinavir: Antipsychotic Agents (Phenothiazines) may enhance the arrhythmogenic effect of Saquinavir. Risk X: Avoid combination
Secretin: Anticholinergic Agents may diminish the therapeutic effect of Secretin. Management: Avoid concomitant use of anticholinergic agents and secretin. Discontinue anticholinergic agents at least 5 half-lives prior to administration of secretin. Risk D: Consider therapy modification
Serotonergic Agents (High Risk): May enhance the adverse/toxic effect of Antipsychotic Agents. Specifically, serotonergic agents may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotic Agents may enhance the serotonergic effect of Serotonergic Agents (High Risk). This could result in serotonin syndrome. Risk C: Monitor therapy
Sodium Phosphates: Agents With Seizure Threshold Lowering Potential may enhance the adverse/toxic effect of Sodium Phosphates. Specifically, the risk of seizure or loss of consciousness may be increased in patients with significant sodium phosphate-induced fluid or electrolyte abnormalities. Risk C: Monitor therapy
Sulpiride: Antipsychotic Agents may enhance the adverse/toxic effect of Sulpiride. Risk X: Avoid combination
Suvorexant: CNS Depressants may enhance the CNS depressant effect of Suvorexant. Management: Dose reduction of suvorexant and/or any other CNS depressant may be necessary. Use of suvorexant with alcohol is not recommended, and the use of suvorexant with any other drug to treat insomnia is not recommended. Risk D: Consider therapy modification
Tetrabenazine: May enhance the adverse/toxic effect of Antipsychotic Agents. Risk C: Monitor therapy
Thalidomide: CNS Depressants may enhance the CNS depressant effect of Thalidomide. Risk X: Avoid combination
Thiazide and Thiazide-Like Diuretics: Anticholinergic Agents may increase the serum concentration of Thiazide and Thiazide-Like Diuretics. Risk C: Monitor therapy
Thiopental: Antipsychotic Agents (Phenothiazines) may enhance the adverse/toxic effect of Thiopental. Risk C: Monitor therapy
Tiotropium: Anticholinergic Agents may enhance the anticholinergic effect of Tiotropium. Risk X: Avoid combination
Topiramate: Anticholinergic Agents may enhance the adverse/toxic effect of Topiramate. Risk C: Monitor therapy
Trimeprazine: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Triptorelin: Hyperprolactinemic Agents may diminish the therapeutic effect of Triptorelin. Risk X: Avoid combination
Umeclidinium: May enhance the anticholinergic effect of Anticholinergic Agents. Risk X: Avoid combination
Valerian: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Verteporfin: Photosensitizing Agents may enhance the photosensitizing effect of Verteporfin. Risk C: Monitor therapy
Zolpidem: CNS Depressants may enhance the CNS depressant effect of Zolpidem. Management: Reduce the Intermezzo brand sublingual zolpidem adult dose to 1.75 mg for men who are also receiving other CNS depressants. No such dose change is recommended for women. Avoid use with other CNS depressants at bedtime; avoid use with alcohol. Risk D: Consider therapy modification
Jaundice or hyper- or hyporeflexia have been reported in newborn infants following maternal use of phenothiazines. Antipsychotic use during the third trimester of pregnancy has a risk for abnormal muscle movements (extrapyramidal symptoms [EPS]) and withdrawal symptoms in newborns following delivery. Symptoms in the newborn may include agitation, feeding disorder, hypertonia, hypotonia, respiratory distress, somnolence, and tremor; these effects may be self-limiting or require hospitalization. If needed, the minimum effective maternal dose should be used in order to decrease the risk of EPS (ACOG 2008).
Perphenazine is present in breast milk. Based on information from two mother-infant pairs, following maternal use of perphenazine 16 to 24 mg/day, the estimated exposure to the breastfeeding infant would be 0.1% to 0.2% of the weight-adjusted maternal dose (Fortinguerra 2009; Olesen 1990). Infants should be monitored for signs of adverse events; routine monitoring of infant serum concentrations is not recommended (ACOG 2008). According to the manufacturer, the decision to continue or discontinue breastfeeding during therapy should take into account the risk of exposure to the infant and the benefits of treatment to the mother.
Mental status; vital signs (as clinically indicated); weight, height, BMI, waist circumference (baseline; at every visit for the first 6 months; quarterly with stable antipsychotic dose); CBC (as clinically indicated; monitor frequently during the first few months of therapy in patients with pre-existing low WBC or history of drug-induced leukopenia/neutropenia); electrolytes, renal and liver function (annually and as clinically indicated; if BUN becomes abnormal, discontinue treatment); fasting plasma glucose level/HbA1c (baseline, then yearly; in patients with diabetes risk factors or if gaining weight, repeat 4 months after starting antipsychotic, then yearly); lipid panel (baseline; repeat every 2 years if LDL level is normal; repeat every 6 months if LDL level is >130 mg/dL); changes in menstruation, libido, development of galactorrhea, erectile and ejaculatory function (at each visit for the first 12 weeks after the antipsychotic is initiated or until the dose is stable, then yearly); abnormal involuntary movements or parkinsonian signs (baseline; repeat weekly until dose stabilized for at least 2 weeks after introduction and for 2 weeks after any significant dose increase); tardive dyskinesia (every 6 months; high-risk patients every 3 months); visual changes (inquire yearly); ocular examination (yearly in patients >40 years; every 2 years in younger patients) (ADA 2004; Lehman 2004; Marder 2004); fall risk (baseline and periodically during treatment in patients with diseases or on medications that may also increase fall risk).
Schizophrenia:
Timing of serum samples: Draw trough just before next dose (Hiemke 2018).
Therapeutic reference range: 0.6 to 2.4 ng/mL (SI: 1.488 to 5.95 nmol/L) (Hiemke 2018). Note: Dosing should be based on therapeutic response as opposed to serum concentrations, however therapeutic drug monitoring can be used to confirm adherence (APA [Keepers 2020]).
Laboratory alert level: 5 ng/mL (SI: 12.4 nmol/L) have been identified as supratherapeutic and resulting in toxicity (Hiemke 2018).
Perphenazine is a piperazine phenothiazine antipsychotic which blocks dopamine, subtype 2 (D2), receptors in mesolimbocortical and nigrostriatal areas of the brain (APA [Lehman, 2004]).
Onset of action: Schizophrenia: Initial effects may be observed within 1 to 2 weeks of treatment with continued improvements through 4 to 6 weeks (Agid 2003; Levine 2010).
Metabolism: Extensively hepatic to metabolites via sulfoxidation, hydroxylation, dealkylation, and glucuronidation; primarily metabolized by CYP2D6 to N-dealkylated perphenazine, perphenazine sulfoxide, and 7-hydroxyperphenazine (active metabolite with 70% of the activity of perphenazine); Note: Metabolism is subject to genetic polymorphism; CYP2D6 poor metabolizers will have higher plasma concentrations of perphenazine compared with normal or extensive metabolizers.
Bioavailability: 40% (Hiemke 2018)
Half-life elimination: Perphenazine: 9 to 12 hours; 7-hydroxyperphenazine: 10 to 19 hours
Time to peak, serum: Perphenazine: 1 to 3 hours; 7-hydroxyperphenazine: 2 to 4 hours
Older adult: Plasma concentrations per daily ingested dose increase with increasing age.
Tablets (Perphenazine Oral)
2 mg (per each): $1.16 - $1.80
4 mg (per each): $1.59 - $2.39
8 mg (per each): $1.93 - $2.90
16 mg (per each): $2.60 - $3.90
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