Dosage Forms
Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product
Tablet, Oral:
Orap: 1 mg [DSC], 2 mg [DSC] [scored]
Generic: 1 mg, 2 mg
Pharmacology
Mechanism of Action
Pimozide, a diphenylbutylperidine conventional antipsychotic, is a potent centrally-acting dopamine-receptor antagonist resulting in its characteristic neuroleptic effects
Pharmacokinetics/Pharmacodynamics
Absorption
≥50%
Metabolism
Hepatic via N-dealkylation primarily by CYP3A4, but with contributions by CYP1A2 and CYP2D6; significant first-pass effect
Excretion
Urine
Onset of Action
Within 1 week; Maximum effect: 4 to 6 weeks
Time to Peak
Serum: 6 to 8 hours (range: 4 to 12 hours)
Duration of Action
Variable
Half-Life Elimination
Children 6 to 13 years (n=4): Mean ± SD: 66 ± 49 hours; Adults 23 to 39 years (n=7): Mean ± SD: 111 ± 57 hours (Sallee 1987)
Protein Binding
99%
Use: Labeled Indications
Tourette disorder: Suppression of severe motor and phonic tics in patients with Tourette disorder who have failed to respond satisfactorily to standard treatment
Use: Off Label
Delusional infestation (also called delusional parasitosis)c
Data from a limited number of patients studied in double-blind trials and case reports suggest that pimozide may be beneficial for the treatment of delusional infestation (also called delusional parasitosis), however, use of pimozide is limited by its adverse effect profile (eg, QT prolongation).
Contraindications
Hypersensitivity to pimozide or any component of the formulation; severe toxic CNS depression; coma; history of cardiac arrhythmias; congenital long QT syndrome; concurrent use with QTc-prolonging agents; hypokalemia or hypomagnesemia; concurrent use of drugs that are inhibitors of CYP3A4, including concurrent use of the azole antifungals itraconazole and ketoconazole, macrolide antibiotics (eg, clarithromycin or erythromycin [Note: The manufacturer lists azithromycin, dirithromycin, and troleandomycin in its list of contraindicated macrolides; however, azithromycin does not inhibit CYP3A4, but may interact with pimozide on the basis of QTc prolongation]), protease inhibitors (ie, atazanavir, indinavir, nelfinavir, ritonavir, saquinavir), citalopram, escitalopram, nefazodone, sertraline, and other less potent inhibitors of CYP3A4 (eg, fluvoxamine, zileuton); concurrent use with strong CYP2D6 inhibitors (eg, paroxetine); concurrent use with medications that may cause motor or phonic tics (eg, amphetamines, methylphenidate, pemoline) until it is determined if medications or Tourette disorder is causing tics; treatment of simple tics or tics other than Tourette disorder
Canadian labeling: Additional contraindications (not in US labeling): Brain damage; depressive disorders; Parkinson disease; renal impairment; liver disorders; pheochromocytoma; blood dyscrasias; regional or spinal anesthesia; family history of congenital long QT syndrome; acquired long QT syndrome; clinically significant bradycardia
Dosage and Administration
Dosing: Adult
Tourette disorder: Oral: Initial: 1 to 2 mg/day in divided doses, then increase dosage as needed every other day; maximum dose: 10 mg/day or 0.2 mg/kg/day (whichever is less); Note: If therapy requires exceeding dose of 4 mg/day, CYP2D6 geno-/phenotyping should be performed; CYP2D6 poor metabolizers should be dose titrated in ≥14-day increments and should not receive doses in excess of 4 mg/day.
Delusional infestation (also called delusional parasitosis) (off-label): Oral: Initial: 0.5 to 2 mg once daily. Increase dose based on response and tolerability in 1 mg increments every 3 to 7 days up to a usual dosage of 2 to 4 mg daily (doses up to 12 mg daily have been studied, however manufacturer labeling recommends a maximum dose of 10 mg/day or 0.2 mg/kg/day). Consider taper of therapy in decrements of ≥1 mg weekly after adequate relief of symptoms for 1 month; assess for return of symptoms and need for continued long-term treatment (Lorenzo 2004). Additional data may be necessary to further define the role of pimozide in this condition.
Discontinuation of therapy: The manufacturer and American Psychiatric Association (APA), Canadian Psychiatric Association (CPA), and World Federation of Societies of Biological Psychiatry (WFSBP) guidelines recommend gradually tapering antipsychotics to avoid withdrawal symptoms and minimize the risk of relapse (APA [Lehman 2004]; Cerovecki 2013; CPA [Addington 2005]; WFSBP [Hasan 2012]); risk for withdrawal symptoms may be highest with highly anti-cholinergic or dopaminergic antipsychotics (Cerovecki 2013). When stopping antipsychotic therapy in patients with schizophrenia, the CPA guidelines recommend a gradual taper over 6 to 24 months, and the APA guidelines recommend reducing the dose by 10% each month (APA [Lehman 2004]; CPA [Addington 2005]). Continuing anti-parkinsonism agents for a brief period after discontinuation may prevent withdrawal symptoms (Cerovecki 2013). When switching antipsychotics, 3 strategies have been suggested: cross-titration (gradually discontinuing the first antipsychotic while gradually increasing the new antipsychotic), overlap and taper (maintaining the dose of the first antipsychotic while gradually increasing the new antipsychotic, then tapering the first antipsychotic), and abrupt change (abruptly discontinuing the first antipsychotic and either increasing the new antipsychotic gradually or starting it at a treatment dose). Evidence supporting ideal switch strategies and taper rates is limited, and results are conflicting (Cerovecki 2013; Remington 2005).
Dosing: Geriatric
Tourette disorder: Oral: Recommend initial dose of 1 mg/day; periodically attempt gradual reduction of dose to determine if tic persists; follow up for 1 to 2 weeks before concluding the tic is a persistent disease phenomenon and not a manifestation of drug withdrawal. Note: An ECG should be performed baseline and periodically thereafter, especially during dosage adjustment.
Dosing: Pediatric
Note: Slow titration is recommended to improve tolerability; use lowest effective dose. An ECG should be performed baseline and periodically thereafter, especially during dosage adjustment.
Tourette disorder, moderate to severe: Note: Due to potential cardiac toxicity, not recommended as first-line therapy; a trial of standard treatment is necessary before initiating a trial of pimozide therapy (Scahill 2006). Reliable dose-response data in patients younger than 12 years of age with Tourette disorder are lacking. Children ≥2 years and Adolescents: Oral:
Weight-directed dosing: Initial: 0.05 mg/kg/dose once daily, preferably at bedtime; maximum initial dose: 1 mg/dose; may increase dose every third day if needed; maximum daily dose: 0.2 mg/kg/day not to exceed 10 mg/day; in active comparator trials in children ≥7 years old, reported mean effective dose: 2.4 to 3.4 mg/day (range: 1 to 6 mg/day) (Gilbert 2004; Sallee 1997).
Fixed dosing: 0.5 to 1 mg daily; usual daily dose range: 2 to 8 mg/day (AACAP [Murphy 2013])
Note: If therapy requires exceeding dose of 0.05 mg/kg/day, CYP2D6 geno-/phenotyping should be performed; CYP2D6 poor metabolizers should be dose titrated in ≥14-day increments and should not receive doses in excess of 0.05 mg/kg/day, up to 4 mg/day. This is based on a study of simulated multiple-dose pimozide exposures using pharmacokinetic parameters following a single dose in 32 healthy people; CYP2D6 poor metabolizers had higher pimozide exposure, which is a surrogate for arrhythmia risk; the study did not provide guidance for CYP2D6 intermediate or ultra-rapid metabolizers (Rogers 2012).
Dosing adjustment for toxicity: Children ≥2 years and Adolescents:
ECG changes: QTc prolongation >0.47 seconds or >25% above baseline: Do not increase dose further; consider a lower dose.
Neutropenia: Absolute neutrophil count <1,000/mm3: Discontinue pimozide; monitor CBC until recovery.
Neuroleptic malignant syndrome: Discontinue; monitor carefully if therapy is reinitiated.
Tardive dyskinesia signs/symptoms: Consider discontinuing therapy; a possible early sign of tardive dyskinesia is fine vermicular movement of the tongue; if this appears, and the medication is stopped, tardive dyskinesia may not develop.
Dosing: Adjustment for Toxicity
ECG changes: QTc prolongation >0.52 seconds or >25% above baseline: Decrease dose.
Storage
Store at 25°C (77°F); excursion permitted to 15°C to 30°C (59°F to 86°F).
Pimozide Images
Drug Interactions
Abiraterone Acetate: May increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Management: Avoid concurrent use of abiraterone with CYP2D6 substrates that have a narrow therapeutic index whenever possible. When concurrent use is not avoidable, monitor patients closely for signs/symptoms of toxicity. Consider therapy modification
Acetylcholinesterase Inhibitors: May diminish the therapeutic effect of Anticholinergic Agents. Anticholinergic Agents may diminish the therapeutic effect of Acetylcholinesterase Inhibitors. Monitor therapy
Acetylcholinesterase Inhibitors (Central): May enhance the neurotoxic (central) effect of Antipsychotic Agents. Severe extrapyramidal symptoms have occurred in some patients. Monitor therapy
Aclidinium: May enhance the anticholinergic effect of Anticholinergic Agents. Avoid combination
Alcohol (Ethyl): CNS Depressants may enhance the CNS depressant effect of Alcohol (Ethyl). Monitor therapy
Alizapride: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Amifampridine: Agents With Seizure Threshold Lowering Potential may enhance the neuroexcitatory and/or seizure-potentiating effect of Amifampridine. Monitor therapy
Amisulpride: Antipsychotic Agents may enhance the adverse/toxic effect of Amisulpride. Management: Drugs listed as exceptions to this monograph are discussed in further detail in separate drug interaction monographs. Avoid combination
Amphetamines: Antipsychotic Agents may diminish the stimulatory effect of Amphetamines. Monitor therapy
Anticholinergic Agents: May enhance the adverse/toxic effect of other Anticholinergic Agents. Monitor therapy
Anti-Parkinson Agents (Dopamine Agonist): Antipsychotic Agents (First Generation [Typical]) may diminish the therapeutic effect of Anti-Parkinson Agents (Dopamine Agonist). Anti-Parkinson Agents (Dopamine Agonist) may diminish the therapeutic effect of Antipsychotic Agents (First Generation [Typical]). Management: Avoid concomitant therapy if possible and monitor for decreased effects of both agents when these combinations cannot be avoided. Atypical antipsychotics such as clozapine and quetiapine may be less likely to reduce the effects of anti-Parkinson agents. Consider therapy modification
Aprepitant: May increase the serum concentration of Pimozide. Avoid combination
Asunaprevir: May increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Consider therapy modification
Azelastine (Nasal): CNS Depressants may enhance the CNS depressant effect of Azelastine (Nasal). Avoid combination
Blonanserin: CNS Depressants may enhance the CNS depressant effect of Blonanserin. Consider therapy modification
Bosentan: May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers). Monitor therapy
Botulinum Toxin-Containing Products: May enhance the anticholinergic effect of Anticholinergic Agents. Monitor therapy
Brexanolone: CNS Depressants may enhance the CNS depressant effect of Brexanolone. Monitor therapy
Brimonidine (Topical): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Bromopride: May enhance the adverse/toxic effect of Antipsychotic Agents. Avoid combination
Bromperidol: May enhance the CNS depressant effect of CNS Depressants. 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. Consider therapy modification
Cannabidiol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Cannabis: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Chloral Betaine: May enhance the adverse/toxic effect of Anticholinergic Agents. 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. Consider therapy modification
Chlorphenesin Carbamate: May enhance the adverse/toxic effect of CNS Depressants. Monitor therapy
Cimetropium: Anticholinergic Agents may enhance the anticholinergic effect of Cimetropium. Avoid combination
CloBAZam: May increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Monitor therapy
CNS Depressants: May enhance the adverse/toxic effect of other CNS Depressants. Monitor therapy
Conivaptan: May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors). Avoid combination
CYP2D6 Inhibitors (Moderate): May decrease the metabolism of CYP2D6 Substrates (High risk with Inhibitors). Monitor therapy
CYP2D6 Inhibitors (Strong): May increase the serum concentration of Pimozide. Avoid combination
CYP3A4 Inducers (Moderate): May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers). Monitor therapy
CYP3A4 Inducers (Strong): May increase the metabolism of CYP3A4 Substrates (High risk with Inducers). Management: Consider an alternative for one of the interacting drugs. Some combinations may be specifically contraindicated. Consult appropriate manufacturer labeling. Consider therapy modification
CYP3A4 Inhibitors (Moderate): May increase the serum concentration of Pimozide. Avoid combination
CYP3A4 Inhibitors (Strong): May increase the serum concentration of Pimozide. Avoid combination
CYP3A4 Inhibitors (Weak): May increase the serum concentration of Pimozide. Exceptions: Amiodarone; QuiNIDine. Avoid combination
Dabrafenib: May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers). Management: Seek alternatives to the CYP3A4 substrate when possible. If concomitant therapy cannot be avoided, monitor clinical effects of the substrate closely (particularly therapeutic effects). Consider therapy modification
Deferasirox: May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers). Monitor therapy
Deutetrabenazine: May enhance the adverse/toxic effect of Antipsychotic Agents. Specifically, the risk for akathisia, parkinsonism, or neuroleptic malignant syndrome may be increased. Monitor therapy
Dimethindene (Topical): May enhance the CNS depressant effect of CNS Depressants. 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. Monitor therapy
Dronabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Eluxadoline: Anticholinergic Agents may enhance the constipating effect of Eluxadoline. Avoid combination
Enzalutamide: May decrease the serum concentration of Pimozide. Avoid combination
Erdafitinib: May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers). Monitor therapy
Erdafitinib: May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors). Monitor therapy
Esketamine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Fexinidazole [INT]: May enhance the QTc-prolonging effect of QT-prolonging Agents (Moderate Risk). Avoid combination
Flunitrazepam: CNS Depressants may enhance the CNS depressant effect of Flunitrazepam. Consider therapy modification
FLUoxetine: May enhance the QTc-prolonging effect of Pimozide. FLUoxetine may increase the serum concentration of Pimozide. Avoid combination
Fosaprepitant: May increase the serum concentration of Pimozide. The active metabolite aprepitant is likely responsible for this effect. Avoid combination
Fusidic Acid (Systemic): May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors). Avoid combination
Gastrointestinal Agents (Prokinetic): Anticholinergic Agents may diminish the therapeutic effect of Gastrointestinal Agents (Prokinetic). Monitor therapy
Glucagon: Anticholinergic Agents may enhance the adverse/toxic effect of Glucagon. Specifically, the risk of gastrointestinal adverse effects may be increased. Monitor therapy
Glycopyrrolate (Oral Inhalation): Anticholinergic Agents may enhance the anticholinergic effect of Glycopyrrolate (Oral Inhalation). Avoid combination
Glycopyrronium (Topical): May enhance the anticholinergic effect of Anticholinergic Agents. Avoid combination
Grapefruit Juice: May increase the serum concentration of Pimozide. Avoid combination
Guanethidine: Antipsychotic Agents may diminish the therapeutic effect of Guanethidine. Monitor therapy
Haloperidol: Pimozide may enhance the QTc-prolonging effect of Haloperidol. Avoid combination
HYDROcodone: CNS Depressants may enhance the CNS depressant effect of HYDROcodone. Management: Avoid concomitant use of hydrocodone 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. Consider therapy modification
HydrOXYzine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Idelalisib: May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors). Avoid combination
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 anticonvulsants. 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 anticonvulsants. 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 anticonvulsants. Consider therapy modification
Ipratropium (Oral Inhalation): May enhance the anticholinergic effect of Anticholinergic Agents. Avoid combination
Itopride: Anticholinergic Agents may diminish the therapeutic effect of Itopride. Monitor therapy
Kava Kava: May enhance the adverse/toxic effect of CNS Depressants. Monitor therapy
Lefamulin: May enhance the QTc-prolonging effect of QT-prolonging CYP3A4 Substrates. Management: Do not use lefamulin tablets with QT-prolonging CYP3A4 substrates. Lefamulin prescribing information lists this combination as contraindicated. 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. Consider therapy modification
Letermovir: May increase the serum concentration of Pimozide. Avoid combination
Levosulpiride: Anticholinergic Agents may diminish the therapeutic effect of Levosulpiride. Avoid combination
Lithium: May enhance the neurotoxic effect of Antipsychotic Agents. Lithium may decrease the serum concentration of Antipsychotic Agents. Specifically noted with chlorpromazine. Monitor therapy
Lofepramine: May enhance the arrhythmogenic effect of Pimozide. Avoid combination
Lorlatinib: May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers). Management: Avoid concurrent use of lorlatinib with any CYP3A4 substrates for which a minimal decrease in serum concentrations of the CYP3A4 substrate could lead to therapeutic failure and serious clinical consequences. Consider therapy modification
Lumefantrine: May increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Monitor therapy
Magnesium Sulfate: May enhance the CNS depressant effect of CNS Depressants. 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. 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 adult dose of CNS depressant agents by 50% with initiation of concomitant methotrimeprazine therapy. Further CNS depressant dosage adjustments should be initiated only after clinically effective methotrimeprazine dose is established. Consider therapy modification
Methylphenidate: Antipsychotic Agents may enhance the adverse/toxic effect of Methylphenidate. Methylphenidate may enhance the adverse/toxic effect of Antipsychotic Agents. Monitor therapy
Metoclopramide: May enhance the adverse/toxic effect of Antipsychotic Agents. Avoid combination
MetyroSINE: CNS Depressants may enhance the sedative effect of MetyroSINE. Monitor therapy
MetyroSINE: May enhance the adverse/toxic effect of Antipsychotic Agents. Monitor therapy
Mianserin: May enhance the anticholinergic effect of Anticholinergic Agents. Monitor therapy
MiFEPRIStone: May enhance the QTc-prolonging effect of Pimozide. MiFEPRIStone may increase the serum concentration of Pimozide. Management: Avoid pimozide during and 2 weeks following mifepristone for treatment of hyperglycemia in Cushing's syndrome. The interaction magnitude could be lower with single doses used to terminate pregnancy, but neither effect has been studied clinically. Avoid combination
Minocycline (Systemic): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Mirabegron: Anticholinergic Agents may enhance the adverse/toxic effect of Mirabegron. Monitor therapy
Mitotane: May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers). Management: Doses of CYP3A4 substrates may need to be adjusted substantially when used in patients being treated with mitotane. Consider therapy modification
Nabilone: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Nefazodone: May increase the serum concentration of Pimozide. Avoid combination
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. Monitor therapy
Ondansetron: Pimozide may enhance the QTc-prolonging effect of Ondansetron. 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. Consider therapy modification
Orphenadrine: CNS Depressants may enhance the CNS depressant effect of Orphenadrine. Avoid combination
Oxatomide: May enhance the anticholinergic effect of Anticholinergic Agents. Avoid combination
Oxomemazine: May enhance the CNS depressant effect of CNS Depressants. Avoid combination
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. Consider therapy modification
Panobinostat: May increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Monitor therapy
Paraldehyde: CNS Depressants may enhance the CNS depressant effect of Paraldehyde. 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). Monitor therapy
Pentamidine (Systemic): Pimozide may enhance the QTc-prolonging effect of Pentamidine (Systemic). Avoid combination
Perampanel: May enhance the CNS depressant effect of CNS Depressants. Management: Patients taking perampanel with any other drug that has CNS depressant activities should avoid complex and high-risk activities, particularly those such as driving that require alertness and coordination, until they have experience using the combination. Consider therapy modification
Perhexiline: CYP2D6 Substrates (High risk with Inhibitors) may increase the serum concentration of Perhexiline. Perhexiline may increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). 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. Avoid combination
Posaconazole: May increase the serum concentration of QT-prolonging CYP3A4 Substrates. Such increases may lead to a greater risk for proarrhythmic effects and other similar toxicities. Avoid combination
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. Avoid combination
Potassium Citrate: Anticholinergic Agents may enhance the ulcerogenic effect of Potassium Citrate. Avoid combination
Pramlintide: May enhance the anticholinergic effect of Anticholinergic Agents. These effects are specific to the GI tract. Consider therapy modification
Protease Inhibitors: May increase the serum concentration of Pimozide. Avoid combination
QT-prolonging Agents (Highest Risk): May enhance the QTc-prolonging effect of Pimozide. Management: Consider alternatives to this combination. Patients with other risk factors (eg, older age, female sex, bradycardia, hypokalemia, hypomagnesemia, heart disease, and higher drug concentrations) are likely at greater risk for these toxicities. Avoid combination
QT-prolonging Agents (Moderate Risk): Pimozide may enhance the QTc-prolonging effect of QT-prolonging Agents (Moderate Risk). Avoid combination
Quinagolide: Antipsychotic Agents may diminish the therapeutic effect of Quinagolide. Monitor therapy
Ramosetron: Anticholinergic Agents may enhance the constipating effect of Ramosetron. Monitor therapy
Revefenacin: Anticholinergic Agents may enhance the anticholinergic effect of Revefenacin. Avoid combination
Rolapitant: May increase the serum concentration of Pimozide. Avoid combination
Rufinamide: May enhance the adverse/toxic effect of CNS Depressants. Specifically, sleepiness and dizziness may be enhanced. Monitor therapy
Sarilumab: May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers). Monitor therapy
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. Consider therapy modification
Selective Serotonin Reuptake Inhibitors: May enhance the adverse/toxic effect of Pimozide. Management: Drugs listed as exceptions to this monograph are discussed in further detail in separate drug interaction monographs as appropriate. Exceptions: Citalopram; Escitalopram; Vortioxetine. Avoid combination
Selective Serotonin Reuptake Inhibitors: CNS Depressants may enhance the adverse/toxic effect of Selective Serotonin Reuptake Inhibitors. Specifically, the risk of psychomotor impairment may be enhanced. Monitor therapy
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. Monitor therapy
Siltuximab: May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers). Monitor therapy
Simeprevir: May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors). Monitor therapy
Sodium Oxybate: May enhance the CNS depressant effect of CNS Depressants. Management: Consider alternatives to combined use. When combined use is needed, consider minimizing doses of one or more drugs. Use of sodium oxybate with alcohol or sedative hypnotics is contraindicated. Consider therapy modification
Stiripentol: May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors). Management: Use of stiripentol with CYP3A4 substrates that are considered to have a narrow therapeutic index should be avoided due to the increased risk for adverse effects and toxicity. Any CYP3A4 substrate used with stiripentol requires closer monitoring. Consider therapy modification
Sulpiride: Antipsychotic Agents may enhance the adverse/toxic effect of Sulpiride. 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. Consider therapy modification
Tapentadol: May enhance the CNS depressant effect of CNS Depressants. Management: Avoid concomitant use of tapentadol 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. Consider therapy modification
Tetrabenazine: May enhance the adverse/toxic effect of Antipsychotic Agents. Monitor therapy
Tetrahydrocannabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Tetrahydrocannabinol and Cannabidiol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Thalidomide: CNS Depressants may enhance the CNS depressant effect of Thalidomide. Avoid combination
Thiazide and Thiazide-Like Diuretics: Anticholinergic Agents may increase the serum concentration of Thiazide and Thiazide-Like Diuretics. Monitor therapy
Tiotropium: Anticholinergic Agents may enhance the anticholinergic effect of Tiotropium. Avoid combination
Tocilizumab: May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers). Monitor therapy
Topiramate: Anticholinergic Agents may enhance the adverse/toxic effect of Topiramate. Monitor therapy
Trimeprazine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Umeclidinium: May enhance the anticholinergic effect of Anticholinergic Agents. Avoid combination
Zileuton: May increase the serum concentration of Pimozide. Avoid combination
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. Consider therapy modification
Adverse Reactions
Frequencies as reported in adults (limited data) and/or children with Tourette's disorder.
>10%:
Central nervous system: Sedation (70%), akathisia (40%), drowsiness (35%; children: ≤25%), behavioral changes (22% to 25%), hypertonia (15%)
Gastrointestinal: Xerostomia (25%), constipation (20%)
Genitourinary: Impotence (15%)
Neuromuscular & skeletal: Akinesia (40%), weakness (14%)
Ophthalmic: Decreased accommodation (20%), visual disturbance (3% to 20%)
1% to 10%:
Cardiovascular: ECG abnormality (3%)
Central nervous system: Depression (10%), insomnia (10%), speech disturbance (10%), nervousness (5% to 6%), writing difficulty (handwriting change: 5%), headache (3% to 5%), abnormal dreams (3%)
Dermatologic: Skin rash (3%)
Endocrine & metabolic: Increased thirst (5%)
Gastrointestinal: Sialorrhea (6%), diarrhea (5%), dysgeusia (5%), increased appetite (5%), dysphagia (3%)
Neuromuscular & skeletal: Muscle rigidity (10%), stooped posture (10%), hyperkinesia (3%), myalgia (3%), torticollis (3%), tremor (3%)
Ophthalmic: Photophobia (5%)
Frequency not defined (some reported for disorders other than Tourette's disorder):
Cardiovascular: Chest pain, hypertension, hypotension, orthostatic hypotension, prolonged Q-T interval on ECG, syncope, tachycardia, ventricular arrhythmia
Central nervous system: Dizziness, excitement, drug-induced extrapyramidal reaction (dystonia, pseudoparkinsonism, tardive dyskinesia), neuroleptic malignant syndrome, palpitations, seizure
Dermatologic: Diaphoresis, skin irritation
Endocrine & metabolic: Decreased libido, hyponatremia, weight changes (gain/loss)
Gastrointestinal: Anorexia, gastrointestinal distress, nausea, vomiting
Genitourinary: Nocturia
Hematologic & oncologic: Hemolytic anemia
Ophthalmic: Blurred vision, cataract, periorbital edema
Renal: Polyuria
<1%, postmarketing, and/or case reports: Gingival hyperplasia
Warnings/Precautions
Concerns related to adverse effects:
- Altered cardiac conduction: May alter cardiac conduction; life-threatening arrhythmias have occurred with therapeutic doses of antipsychotics. Contraindicated in patients with underlying QT prolongation, in those taking medicines that prolong the QT interval, or cause polymorphic ventricular tachycardia; monitor ECG closely for dose-related QT effects. Sudden unexplained deaths have occurred in patients taking high doses (~1 mg/kg). ECG monitoring recommended periodically during therapy. Use caution with concomitant medication or conditions which cause hypokalemia or hypomagnesemia; correct hypokalemia or hypomagnesemia prior to initiation of therapy.
- 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 neuroleptics, pimozide has a high potency of cholinergic blockade (Yamamura 1976).
- 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 or driving).
- Esophageal dysmotility/Aspiration: Antipsychotic use has been associated with esophageal dysmotility and aspiration; risk increases with age. Use with caution in patients at risk for aspiration pneumonia (ie, 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 [Lehman 2004]; Soares-Weiser 2007). Consider therapy discontinuation with signs/symptoms of tardive dyskinesia.
- Hyperprolactinemia: Antipsychotics are associated with increased prolactin levels; clinical significance of hyperprolactinemia in patients with breast cancer or other prolactin-dependent tumors is unknown.
- Neuroleptic malignant syndrome (NMS): Use may be associated with NMS; monitor for mental status changes, fever, muscle rigidity, and/or autonomic instability; may also be associated with increased CPK, myogloburia, and acute renal failure. Discontinue use; may recur upon rechallenge.
- 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 severe cardiovascular disease.
- Dementia: Elderly patients with dementia-related psychosis treated with antipsychotics are at an increased risk of death compared with 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]). Pimozide is not approved for the treatment of dementia-related psychosis.
- Hepatic impairment: Use with caution in patients with hepatic impairment.
- Renal impairment: Use with caution in patients with renal impairment.
- Seizure disorder: Use with caution in patients at risk of seizures, including those with a history of seizures, head trauma, brain damage, alcoholism, or concurrent therapy with medications which may lower seizure threshold.
Concurrent drug therapy issues:
- Drug-drug interactions: Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.
Special populations:
- CYP2D6 poor metabolizers: Increased pimozide serum concentration and prolonged half-life are observed in CYP2D6 poor metabolizers; dose adjustment required
Other warnings/precautions:
- Discontinuation of therapy: When discontinuing antipsychotic therapy, the manufacturer and American Psychiatric Association (APA), Canadian Psychiatric Association (CPA), and World Federation of Societies of Biological Psychiatry (WFSBP) guidelines recommend gradually tapering antipsychotics to avoid physical withdrawal symptoms, including anorexia, anxiety, diaphoresis, diarrhea, dizziness, dyskinesia, headache, myalgia, nausea, paresthesia, restlessness, tremulousness, and vomiting (APA [Lehman 2004]; CPA [Addington 2005]; Lambert 2007; WFSBP [Hasan 2012]). The risk of withdrawal symptoms is highest following abrupt discontinuation of highly anti-cholinergic or dopaminergic antipsychotics (Cerovecki 2013). Additional factors such as duration of antipsychotic exposure, the indication for use, medication half-life, and risk for relapse should be considered. In schizophrenia, there is no reliable indicator to differentiate the minority who will not from the majority who will relapse with drug discontinuation. However, studies in which the medication of well-stabilized patients were discontinued indicate that 75% of patients relapse within 6 to 24 months. Indefinite maintenance antipsychotic medication is generally recommended, and especially for patients who have had multiple prior episodes or 2 episodes within 5 years (APA [Lehman 2004]).
Monitoring Parameters
Mental status; vital signs (as clinically indicated); ECG (baseline and periodically thereafter, especially during dosage adjustment); CYP2D6 genotyping or phenotyping (baseline); 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 (annually and as clinically indicated; perform potassium measurement at baseline); liver function (annually and as clinically indicated); 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); fasting 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 (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).
Pregnancy
Pregnancy Risk Factor
C
Pregnancy Considerations
Adverse events were observed in some animal reproduction studies. 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.
Patient Education
- Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)
- Patient may experience fatigue, loss of strength and energy, constipation, nausea, vomiting, lack of appetite, trouble sleeping, increased saliva, anxiety, weight gain, weight loss, or dry mouth. Have patient report immediately to prescriber signs of infection, vision changes, abnormal movements, twitching, change in balance, difficulty swallowing, difficulty speaking, abnormal heartbeat, chest pain, fast heartbeat, severe dizziness, passing out, severe headache, tremors, difficulty moving, rigidity, seizures, agitation, depression, change in amount of urine passed, behavioral changes, unable to pass urine, decreased sex drive, sexual dysfunction, signs of neuroleptic malignant syndrome (fever, muscle cramps or stiffness, dizziness, severe headache, confusion, change in thinking, fast heartbeat, abnormal heartbeat, or sweating a lot), or signs of tardive dyskinesia (unable to control body movements; tongue, face, mouth, or jaw sticking out; mouth puckering; or puffing cheeks) (HCAHPS).
- Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.
Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.
