OUTLINE: HALOPERIDOL

Outline: Haloperidol (HALDOL)

Description

Haloperidol (marketed as HALDOL) is among the major antipsychotic medication (FDA, 2017)

Its chemical designation is 4-[4-(p-chlorophenyl)-4-hydroxypiperidino]-4-fluorobutyrophenone and the structural formula is:

HALDOL is administered as an intramuscular injection, which contains 5 mg Haloperidol as the lactate and PH-adjusting lactic acid with a PH of between 3.0 and 3.6 (FDA, 2017).

Indications

HALDOL is FDA-indicated for treating Schizophrenia

It is also indicated for controlling vocal utterances and tics of Tourettes Disorder (FDA, 2017)

Although not FDA-indicated, HALDOL has also been found to be effective in the treatment of delirium in critical illness (Girard et al., 2018)

Mechanism of Action

HALDOLs specific mechanism of action is not clearly established (FDA, 2017)

Drug-Drug Interactions

The risks of using HALDOL with other drugs could be either pharmacokinetics (altering plasma levels) or pharmacodynamic (FDA, 2017).

Pharmacokinetic Interactions

HALDOLs metabolism occurs through several routes, including the enzyme system of the cytochrome P450 and glucuronidation. Drugs that inhibit any of these routes may increase Haloperidol concentrations and consequently, adverse events, including QT prolongation and an increased risk of cardiac arrest (FDA, 2017).

Thus, clinicians ought to carefully monitor patients clinical status for adverse events when any such drugs are prescribed to complement HALDOL therapy.

Mild to moderate increases in haloperidol concentrations have been reported when Haloperidol is used with drugs that induce or inhibit CYP2D6 or CYP3A4 isoenzymes, such as Buspirone, fluoxetine, sertraline, promethazine, and quinidine (FDA, 2017)

Haloperidol plasma levels have also been shown to reduce significantly when HALDOL therapy is complemented with drugs that cause enzyme inductions such as Carbamazepine and Rifampin (FDA, 2017).

Pharmacodynamic Interactions

Haloperidol is associated with a heightened risk of QT-prolongation, thus clinicians are advised to be cautious and do regular clinical monitoring when developing prescriptions for patients with pre-existing QT-prolongation conditions such as electrolyte imbalance, hypokalemia, and QT syndrome (FDA, 2017).

Anti-Parkinson medication have been associated with increased...

Thus, clinicians are advised to discontinue HALDOL therapy if they have to prescribe anti-Parkinson medication (FDA, 2017).

Metabolic inhibitors Paroxetine (20mg/day) and Keteconazole (400mg/day) have been associated with QTc (corrected QT interval) increases when used in combination with haloperidol (FDA, 2017). Thus, it may be prudent to reduce the dosage of haloperidol when it is prescribed together with metabolic inhibitors (FDA, 2017).

HALDOL, like other antipsychotic medication, has been shown to potentiate CNS depressants such as alcohol, opiates, and anesthetics

Dosage and Administration

The...

…counter respiratory depression using mechanical respirators or artificial respiration

Use of vasopressor agents, concentrated albumin, and intravenous plasma and fluids to counter hypotension. The clinician should monitor the patient until the ECG normalizes

Administering anti-Parkinson medication to counter severe extrapyramidal reactions

Comorbidities Considerations

Haloperidol is contraindicated in individuals with Parkinsons disease and hypertension due to QT prolongation and drug-drug interactions with anti-Parkinson medication (FDA, 2017).

Effective ECG monitoring is crucial for hypertensive patients.

The clinician may have to discontinue haloperidol before beginning anti-Parkinson medication

Haloperidol is not approved for use with dementia patients due to a heightened risk of death (FDA, 2017).

Legal and Ethical Considerations

Use of Haloperidol in pediatric patients in the absence of clinical trials adequately proving efficacy raises ethical questions (FDA, 2017)

Concerns surrounding overuse - Clinicians face an ethical question of whether to prescribe Haloperidol as an immediate response to psychotic aggression with its serious contraindications or prescribe a less effective psychotic drug with fewer contraindications (Ostinelli et al., 2017)

Pertinent Patient Education Considerations

Patients need to be aware that:

There is a need for strict compliance with the prescribed doses to avoid sudden treatment withdrawal symptoms that may resemble those of tardive dyskinesia (FDA, 2017)

Gradual withdrawal under a clinicians guidance…