Haloperidol


Haloperidol, sold under the brand name Haldol among others, is a typical antipsychotic medication. Haloperidol is used in the treatment of schizophrenia, tics in Tourette syndrome, mania in bipolar disorder, delirium, agitation, acute psychosis, and hallucinations from alcohol withdrawal. It may be used by mouth or injection into a muscle or a vein. Haloperidol typically works within 30 to 60 minutes. A long-acting formulation may be used as an injection every four weeks for people with schizophrenia or related illnesses, who either forget or refuse to take the medication by mouth.
Haloperidol may result in movement disorders such as tardive dyskinesia, and akathisia, both of which may be permanent. Neuroleptic malignant syndrome and QT interval prolongation may occur, the latter particularly with IV administration. In older people with psychosis due to dementia it results in an increased risk of death. When taken during pregnancy it may result in problems in the infant. It should not be used by people with Parkinson's disease.
Haloperidol was discovered in 1958 by the team of Paul Janssen, prepared as part of a structure-activity relationship investigation into analogs of pethidine. It is on the World Health Organization's List of Essential Medicines. It is the most commonly used typical antipsychotic. In 2020, it was the 303rd most commonly prescribed medication in the United States, with more than 1million prescriptions.

Medical uses

Haloperidol is used in the control of the symptoms of:
Haloperidol was considered indispensable for treating psychiatric emergency situations. However, the newer atypical drugs have gained a greater role in a number of situations, as outlined in a series of consensus reviews published between 2001 and 2005.
In a 2013 comparison of 15 antipsychotics in schizophrenia, haloperidol demonstrated standard effectiveness. It was 13–16% more effective than ziprasidone, chlorpromazine, and asenapine, approximately as effective as quetiapine and aripiprazole, and 10% less effective than paliperidone. A 2013 systematic review compared haloperidol to placebo in schizophrenia:
In contrast to certain other antipsychotics like risperidone, haloperidol is ineffective as a hallucinogen antidote or "trip killer" in blocking the effects of serotonergic psychedelics like psilocybin and lysergic acid diethylamide.

Pregnancy and lactation

Data from animal experiments indicate haloperidol is not teratogenic, but is embryotoxic in high doses. In humans, no controlled studies exist. Reports in pregnant women revealed possible damage to the fetus, although most of the women were exposed to multiple drugs during pregnancy. In addition, reports indicate neonates exposed to antipsychotic drugs are at risk for extrapyramidal and/or withdrawal symptoms following delivery, such as agitation, hypertonia, hypotonia, tremor, somnolence, respiratory distress, and feeding disorder. Following accepted general principles, haloperidol should be given during pregnancy only if the benefit to the mother clearly outweighs the potential fetal risk.
Haloperidol is excreted in breast milk. A few studies have examined the impact of haloperidol exposure on breastfed infants and in most cases, there were no adverse effects on infant growth and development.

Other considerations

During long-term treatment of chronic psychiatric disorders, the daily dose should be reduced to the lowest level needed for maintenance of remission. Sometimes, it may be indicated to terminate haloperidol treatment gradually. In addition, during long-term use, routine monitoring including measurement of BMI, blood pressure, fasting blood sugar, and lipids, is recommended due to the risk of side effects.
Other forms of therapy should be instituted properly.
PET imaging studies have suggested low doses are preferable. Clinical response was associated with at least 65% occupancy of D2 receptors, while greater than 72% was likely to cause hyperprolactinaemia and over 78% associated with extrapyramidal side effects. Doses of haloperidol greater than 5 mg increased the risk of side effects without improving efficacy. Patients responded with doses under even 2 mg in first-episode psychosis. For maintenance treatment of schizophrenia, an international consensus conference recommended a reduction dosage by about 20% every 6 months until a minimal maintenance dose is established.
  • Depot forms are also available; these are injected deeply intramuscularly at regular intervals. The depot forms are not suitable for initial treatment, but are suitable for patients who have demonstrated inconsistency with oral dosages.
The decanoate ester of haloperidol has a much longer duration of action, so is often used in people known to be noncompliant with oral medication. A dose is given by intramuscular injection once every two to four weeks. The IUPAC name of haloperidol decanoate is piperidin-4-yl] decanoate.
Topical formulations of haloperidol should not be used as treatment for nausea because research does not indicate this therapy is more effective than alternatives.

Adverse effects

Sources for the following lists of adverse effects:
As haloperidol is a high-potency typical antipsychotic, it tends to produce significant extrapyramidal side effects. According to a 2013 meta-analysis of the comparative efficacy and tolerability of 15 antipsychotic drugs it was the most prone of the 15 for causing extrapyramidal side effects.
With more than 6 months of use 14 percent of users gain weight. Haloperidol may be neurotoxic.
Prolonged use of the drug can lead to mental dependence.
Common
Unknown frequency
Rare