Haloperidol - Kieran's Medical Notes

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Haloperidol

Class

Butyrophenone typical antipsychotic

Indications

Schizophrenia
Acute psychotic states and delirium

Schizoaffective disorder
Delusional disorders

Ballism
Tourette syndrome (a drug of choice)
Occasionally as adjunctive therapy in mental retardation and the chorea of huntington disease
Intractable hiccups
ADHD
Severe nausea and vomiting

Administration/Absorption

Oral
IM
IV

Dosage

Plasma levels of 4 to 25 micrograms per liter are required for therapeutic action.

Distribution

92% protein bound

Mechanism

Strong central antidopaminergic action
Effective dopaminergic receptor blockage in the mesocortex and the limbic system of the brain

strong activity against delusions and hallucinations

Blocks the dopaminergic action in the nigrostriatal pathways

Probable reason for the high frequency of extrapyramidal-motoric side effects (dystonias, akathisia, pseudoparkinsonism).

Minor antihistaminic and anticholinergic properties
Sedative properties

Strong action against psychomotor agitation due to a specific action in the limbic system
However, in some cases, haloperidol may worsen psychomotor agitation via its potent dopamine receptor antagonism

The peripheral antidopaminergic effects

Account for its strong antiemetic activity
Also leads also to a relaxation of the gastric sphincter muscle and an increased release of the hormone prolactin

Possible emergence of breast enlargement and secretion of milk (galactorrhea) in both sexes

Excretion

Plasma concentrations of haloperidol decanoate reach a peak at about 6 days after the injection, falling thereafter, with an approx. half-life of 3 weeks
Liver metabolism

Side effects

Strong early and late extrapyramidal side effects
Akathisia
Dry mouth
Lethargy
Muscle-stiffness, muscle-cramping, restlessness, tremors
Rabbit syndrome
weight-gain
Depression, severe enough to result in suicide, is quite often seen during long-term treatment
Symptoms of dystonia may occur in susceptible individuals during the first few days of treatment
Neuroleptic malignant syndrome
QT prolongation with sudden death
Thromboembolic complications

Interactions

Contraindications

Absolute

Preexisting coma, acute stroke
Severe intoxication with alcohol or other central depressant drugs
Known allergy against haloperidol or other butyrophenones or other drug ingredients
Known heart disease; when combined will tend towards cardiac arrest

Special caution needed

Preexisting Parkinson's disease [23] or dementia with Lewy bodies
Patients at special risk for the development of QT prolongation

hypokalemia
concomitant use of other drugs causing QT prolongation)

Compromised liver-function
Patients with hyperthyreosis
IV injections: risk of hypotension or orthostatic collapse

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