Thursday, February 15, 2018

Haloperidol - antipsychotic drug and its therapeutic uses

DESCRIPTION :
Haloperidol is a typical antipsychotic medication,which trade name is  Haldol.
It was discovered in 1958 by Poul Janssen. It was made from  meperidine. It is on the WHO Model List of Essential Medicines , which is most important medicine for health system.

MECHANISM OF ACTION:
This drug appears to depress the CNS at the subcorticol level of the brain, midbrain, and brain stem reticular formation.
It inhibits the ascending reticular activating system of the brain stem, thereby interrupting the impulse between the diencephalon and the cortex.
The drug may antagonize the action of gultamic acid within the extrapyramidal system, and inhibitions of catecholamine receptors.
Sometimes it has directly affect the chemoreceptor trigger zone (CTZ) through the blocking of dopamine receptors in the  CTZ.

PHARMACOLOGY:
Absorption: Oral 60%
Metabolism: Hepatic
Half Life: 3 weeks
Excretion: Billary (faeces,  in urinary)
Protein binding: 92%
Haloperidol is a psychotropic agent  which act at all levels of the central nervous system – primarily at subcorticol levels as well as on multiple organs.
It has strong antiadrenergic and weaker peripheral anticholinergic activity ; ganglionic blocking action is relatively slight .
It also possesses slight antihistaminic and antiserotonin activity.

  THERAPEUTIC USES:
Haloperidol is used to treat schizophrenia.
It is also used to control motor and speech tics in people with Tourette’s  syndrome.
It is also used in mania in bipolar disorder.
Treatment in intractable hiccups.
Hallucinations in alcohol withdrawal.

ADVERSE EFFECTS:
Seizure ( due to abnormal electrical activity in the brain)
Tremor (it is extrapyramidal side effect  which is occurs due to excessive amount of dopamine blocker)
Pale skin
Chest pain (due to coronary vasoconstriction)
Cough (with yellow or green mucus)
Sudden mood changes, agitation,
Jaundice (yellowing of skin or eyes , due to higher amount of bilirubin)
Headache
Insomnia, dry mouth, blurred vision,
Urinating less (due to relaxation action on ureter and urinary bladder)

DRUG-DRUG  INTERACTION :
Aclidinium +Haloperidol =  It may increase the anticholinergic activity of haloperidol.
Amoxapin, Amitriptyline +Haloperidol = The risk or severity adverse effect can be increased when amitriptyline is combined with haloperidol.
Amphetamine +Haloperidol = It may decrease the similarly activities of haloperidol.
Aripiprazole +Haloperidol = It may increase the QT prolonging activities of haloperidol.
Azelastin +Haloperidol = Haloperidol may increase the central nervous system depressant (CNS depressant) activities of azelastine.
Levodopa + Haloperidol = Decreased action of levodopa.



REFERENCE 
Goodman & Gilman’s Pharmacological Basis of Therapeutics, 10th Edition (MC Graohill 2001)

WHO Model List of Essential Medicines October 2013, pp.7, 35-Retrived 22 April 2014.

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