May cause anticholinergic effects (confusion, agitation, constipation, xerostomia, blurred vision, urinary retention). Therefore, they should be used with caution in patients with decreased gastrointestinal motility, urinary retention, BPH, xerostomia, or visual problems. Conditions which also may be exacerbated by cholinergic blockade include narrow-angle glaucoma (screening is recommended) and worsening of myasthenia gravis. Relative to other neuroleptics, haloperidol has a low potency of cholinergic blockade.

May cause extrapyramidal symptoms, including pseudoparkinsonism, acute dystonic reactions, akathisia, and tardive dyskinesia (risk of these reactions is high relative to other neuroleptics). May be associated with neuroleptic malignant syndrome (NMS) or pigmentary retinopathy.

Cardiovascular: Hyper-/hypotension, tachycardia, arrhythmia, abnormal T waves with prolonged ventricular repolarization, torsade de pointes (case-control study ~4%)

Central nervous system: Restlessness, anxiety, extrapyramidal symptoms, dystonic reactions, pseudoparkinsonian signs and symptoms, tardive dyskinesia, neuroleptic malignant syndrome (NMS), altered central temperature regulation, akathisia, tardive dystonia, insomnia, euphoria, agitation, drowsiness, depression, lethargy, headache, confusion, vertigo, seizure

Dermatologic: Hyperpigmentation, pruritus, rash, contact dermatitis, alopecia, photosensitivity (rare)

Endocrine & metabolic: Amenorrhea, galactorrhea, gynecomastia, sexual dysfunction, lactation, breast engorgement, mastalgia, menstrual irregularities, hyperglycemia, hypoglycemia, hyponatremia

Gastrointestinal: Nausea, vomiting, anorexia, constipation, diarrhea, hypersalivation, dyspepsia, xerostomia

Genitourinary: Urinary retention, priapism

Hematologic: Cholestatic jaundice, obstructive jaundice

Ocular: Blurred vision

Respiratory: Laryngospasm, bronchospasm

Miscellaneous: Heat stroke, diaphoresis

Anticholinergics: May inhibit the therapeutic response to haloperidol and excess anticholinergic effects may occur; tardive dyskinesias have also been reported; includes benztropine and trihexyphenidyl

Antihypertensives: Concurrent use of haloperidol with an antihypertensive may produce additive hypotensive effects (particularly orthostasis)

Bromocriptine: Antipsychotics inhibit the ability of bromocriptine to lower serum prolactin concentrations

Chloroquine: Serum concentrations of haloperidol may be increased by chloroquine

CNS depressants: Sedative effects may be additive; monitor for increased effect; includes barbiturates, benzodiazepines, narcotic analgesics, ethanol and other sedative agents

CYP2D6 inhibitors: May increase the levels/effects of haloperidol. Example inhibitors include chlorpromazine, delavirdine, fluoxetine, miconazole, paroxetine, pergolide, quinidine, quinine, ritonavir, and ropinirole.

CYP2D6 substrates: Haloperidol may increase the levels/effects of CYP2D6 substrates. Example substrates include amphetamines, selected beta-blockers, dextromethorphan, fluoxetine, lidocaine, mirtazapine, nefazodone, paroxetine, risperidone, ritonavir, thioridazine, tricyclic antidepressants, and venlafaxine.

CYP2D6 prodrug substrates: Haloperidol may decrease the levels/effects of CYP2D6 prodrug substrates. Example prodrug substrates include codeine, hydrocodone, oxycodone, and tramadol.

CYP3A4 inducers: CYP3A4 inducers may decrease the levels/effects of haloperidol. Example inducers include aminoglutethimide, carbamazepine, nafcillin, nevirapine, phenobarbital, phenytoin, and rifamycins.

CYP3A4 inhibitors: May increase the levels/effects of haloperidol. Example inhibitors include azole antifungals, ciprofloxacin, clarithromycin, diclofenac, doxycycline, erythromycin, imatinib, isoniazid, nefazodone, nicardipine, propofol, protease inhibitors, quinidine, and verapamil.

CYP3A4 substrates: Haloperidol may increase the levels/effects of CYP3A4 substrates. Example substrates include benzodiazepines, calcium channel blockers, cyclosporine, mirtazapine, nateglinide, nefazodone, sildenafil (and other PDE-5 inhibitors), tacrolimus, and venlafaxine. Selected benzodiazepines (midazolam and triazolam), cisapride, ergot alkaloids, selected HMG-CoA reductase inhibitors (lovastatin and simvastatin), and pimozide are generally contraindicated with strong CYP3A4 inhibitors.

Indomethacin: Haloperidol in combination with indomethacin may result in drowsiness, tiredness, and confusion; monitor for adverse effects

Inhalation anesthetics: Haloperidol in combination with certain forms of induction anesthesia may produce peripheral vasodilitation and hypotension

Levodopa: Haloperidol may inhibit the antiparkinsonian effect of levodopa; avoid this combination

Lithium: Haloperidol may produce neurotoxicity with lithium; this is a rare effect

Methyldopa: Effect of haloperidol may be altered; enhanced effects, as well as reduced efficacy have been reported

Metoclopramide: May increase extrapyramidal symptoms (EPS) or risk.

Nefazodone: Haloperidol and nefazodone may produce additive CNS toxicity, including sedation

Propranolol: Serum concentrations of haloperidol may be increased

Quinidine: May increase haloperidol concentrations; monitor for EPS and/or QTc prolongation

SSRIs: Fluoxetine, fluvoxamine, and paroxetine may inhibit the metabolism of haloperidol resulting in EPS; monitor for EPS

Sulfadoxine-pyrimethamine: May increase fluphenazine concentrations

Tricyclic antidepressants: Concurrent use may produce increased toxicity or altered therapeutic response

Trazodone: Haloperidol and trazodone may produce additive hypotensive effects

Ethanol: Avoid ethanol (may increase CNS depression).

Herb/Nutraceutical: Avoid valerian, St John's wort, kava kava, gotu kola (may increase CNS depression).

Protect oral dosage forms from light

Haloperidol lactate injection should be stored at controlled room temperature and protected from light, freezing and temperatures >40°C; exposure to light may cause discoloration and the development of a grayish-red precipitate over several weeks

Haloperidol lactate may be administered IVPB or I.V. infusion in D5W solutions; NS solutions should not be used due to reports of decreased stability and incompatibility

Standardized dose: 0.5-100 mg/50-100 mL D5W

Stability of standardized solutions is 38 days at room temperature (24°C)

Y-site administration: Compatible: Amifostine, amsacrine, aztreonam, cimetidine, cisatracurium, cladribine, dobutamine, docetaxel, dopamine, doxorubicin liposome, etoposide phosphate, famotidine, filgrastim, fludarabine, gatifloxacin, gemcitabine, granisetron, lidocaine, linezolid, lorazepam, melphalan, midazolam, nitroglycerin, norepinephrine ondansetron, paclitaxel, phenylephrine, propofol, remifentanil, sufentanil, tacrolimus, teniposide, theophylline, thiotepa, vinorelbine. Incompatible: Allopurinol, amphotericin B cholesteryl sulfate complex, cefepime, fluconazole, foscarnet, heparin, piperacillin/tazobactam, sargramostim. Variable (consult detailed reference): Sodium nitroprusside

Compatibility in syringe: Compatible: Hydromorphone, sufentanil. Incompatible: Diphenhydramine, heparin, hydroxyzine, ketorolac. Variable (consult detailed reference): Benztropine, cyclizine, diamorphine, morphine

Onset of action: Sedation: I.V.: ~1 hour

Duration: Decanoate: ~3 weeks

Distribution: Crosses placenta; enters breast milk

Protein binding: 90%

Metabolism: Hepatic to inactive compounds

Bioavailability: Oral: 60%

Half-life elimination: 20 hours

Time to peak, serum: 20 minutes

Excretion: Urine (33% to 40% as metabolites) within 5 days; feces (15%)

Children: 3-12 years (15-40 kg): Oral:

Initial: 0.05 mg/kg/day or 0.25-0.5 mg/day given in 2-3 divided doses; increase by 0.25-0.5 mg every 5-7 days; maximum: 0.15 mg/kg/day

Usual maintenance:

Agitation or hyperkinesia: 0.01-0.03 mg/kg/day once daily

Nonpsychotic disorders: 0.05-0.075 mg/kg/day in 2-3 divided doses

Psychotic disorders: 0.05-0.15 mg/kg/day in 2-3 divided doses

Children 6-12 years: Sedation/psychotic disorders: I.M. (as lactate): 1-3 mg/dose every 4-8 hours to a maximum of 0.15 mg/kg/day; change over to oral therapy as soon as able

Adults:

Psychosis:

Oral: 0.5-5 mg 2-3 times/day; usual maximum: 30 mg/day

I.M. (as lactate): 2-5 mg every 4-8 hours as needed

I.M. (as decanoate): Initial: 10-20 times the daily oral dose administered at 4-week intervals

Maintenance dose: 10-15 times initial oral dose; used to stabilize psychiatric symptoms

Delirium in the intensive care unit (unlabeled use, unlabeled route):

I.V.: 2-10 mg; may repeat bolus doses every 20-30 minutes until calm achieved then administer 25% of the maximum dose every 6 hours; monitor ECG and QTc interval

Intermittent I.V.: 0.03-0.15 mg/kg every 30 minutes to 6 hours

Oral: Agitation: 5-10 mg

Continuous intravenous infusion (100 mg/100 mL D5W): Rates of 3-25 mg/hour have been used

Rapid tranquilization of severely-agitated patient (unlabeled use): Administer every 30-60 minutes:

Oral: 5-10 mg

I.M.: 5 mg

Average total dose (oral or I.M.) for tranquilization: 10-20 mg

Elderly: Initial: Oral: 0.25-0.5 mg 1-2 times/day; increase dose at 4- to 7-day intervals by 0.25-0.5 mg/day; increase dosing intervals (twice daily, 3 times/day, etc) as necessary to control response or side effects

Hemodialysis/peritoneal dialysis: Supplemental dose is not necessary

Therapeutic: 5-15 ng/mL (SI: 10-30 nmol/L) (psychotic disorders - less for Tourette's and mania)

Toxic: >42 ng/mL (SI: >84 nmol/L)

Delirium in the ICU Patient: Set goals for control of delirium. Haloperidol has not been studied in well-controlled trials enrolling ICU patients with acute delirium or agitation. Avoid use in patients with underlying QT prolongation, in those taking medicines that prolong the QT interval, or cause polymorphic ventricular tachycardia. Even when used at recommended doses, cardiac arrhythmias have occurred. Monitor ECG closely for dose-related QT effects. Once the patient has been stable for a few days, taper the dose and reassess the patient. Haloperidol may cause extrapyramidal symptoms. It is the most frequently implicated antipsychotic associated with neuroleptic malignant syndrome.

Injection, oil, as decanoate (Haldol® Decanoate): 50 mg/mL (1 mL, 5 mL); 100 mg/mL (1 mL, 5 mL) [contains benzyl alcohol, sesame oil]

Injection, solution, as lactate (Haldol®): 5 mg/mL (1 mL, 10 mL)

Solution, oral concentrate, as lactate: 2 mg/mL (15 mL, 120 mL)

Tablet: 0.5 mg, 1 mg, 2 mg, 5 mg, 10 mg, 20 mg

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