Antipsychotic

Haloperidol 5 mg, n50

International Nonproprietary Name (INN): Haloperidol

Pharmaceutic group: Antipsychotic

Presentation:

Tablets 1.5 mg n50 and 5 mg n50.

Available with prescription

Question?

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Haloperidol is a typical antipsychotic. It is in the butyrophenone class of antipsychotic medications and has pharmacological effects similar to the phenothiazines.

Haloperidol is an older antipsychotic used in the treatment of schizophrenia and in the treatment of acute psychotic states and delirium. A long-acting decanoate ester is used as an injection given every 4 weeks to people with schizophrenia or related illnesses who have a poor compliance with medication and suffer frequent relapses of illness, or to overcome the drawbacks inherent to its orally administered counterpart that burst dosage increases risk or intensity of side effects. In some countries, injections of antipsychotics such as haloperidol can be ordered by a court at the request of a psychiatrist.

Haloperidol was discovered by Paul Janssen. It was developed in 1958 by the Belgian company Janssen Pharmaceutica and submitted to the first of clinical trials in Belgium later that year.

Haloperidol was approved by the U.S. Food and Drug Administration (FDA) on April 12, 1967, later marketed in the U.S. and other countries under the brand name Haldol by McNeil Laboratories.

Haloperidol is an antipsychotic butyrophenone. Due to its strong central antidopaminergic action, it is classified as a highly potent neuroleptic. It is approximately 50 times more potent than chlorpromazine (sold under the brand name Thorazine, among others) on a weight basis (50 mg chlorpromazine is equivalent to 1 mg haloperidol). Haloperidol possesses a strong activity against delusions and hallucinations, most likely due to an effective dopaminergic receptor blockage in the mesocortex and the limbic system of the brain. It blocks the dopaminergic action in the nigrostriatal pathways, which is the probable reason for the high frequency of extrapyramidal-motoric side effects (dystonias, akathisia, pseudoparkinsonism).

Haloperidol has minor antihistaminic and anticholinergic properties, therefore cardiovascular and anticholinergic side effects such as hypotension, dry mouth, constipation, etc. are seen quite infrequently, compared with less-potent neuroleptics such as chlorpromazine. Haloperidol also has sedative properties and displays a 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. Dopamine receptor antagonism, mainly of the D2 receptor subtype, can cause akathisia, psychomotor agitation, anxiety, and restlessness, which may worsen the condition of some patients.

The peripheral antidopaminergic effects of haloperidol account for its strong antiemetic activity. There, it acts at the chemoreceptor trigger zone (CTZ). Haloperidol is useful to treat severe forms of nausea/emesis such as those resulting from chemotherapy. The peripheral effects lead also to a relaxation of the gastric sphincter muscle and an increased release of the hormone prolactin, with the possible emergence of breast enlargement and secretion of milk (galactorrhea) in both sexes.

INDICATION. A comprehensive review of haloperidol has found it to be an effective agent in treatment of symptoms associated with schizophrenia. Haloperidol is also used in the control of the symptoms of:

• Acute psychosis, such as drug psychosis (LSD, psilocybin, amphetamines, ketamine, and phencyclidine), psychosis associated with high fever or metabolic disease;

• Acute manic phases until the concomitantly given first-line drugs such as lithium or valproate are effective;

• Hyperactivity, aggression;

• Acute delirium;

• Otherwise uncontrollable severe behavioral disorders in children and adolescents;

• Agitation and confusion associated with cerebral sclerosis;

• Adjunctive treatment of alcohol and opioid withdrawal;

• Treatment of severe nausea and emesis in postoperative and palliative care, especially with regards to palliating adverse effects of radiation therapy and chemotherapy in oncology;

• Treatment of neurological disorders such as tic disorders, Tourette syndrome, and chorea;

• Adjunctive treatment of severe chronic pain, always together with analgesics;

• Therapeutic trial in personality disorders such as borderline personality disorder;

• Also used in the treatment of intractable hiccups.

During long-term treatment of chronic psychiatric disorders, it should be tried—in regular intervals—to reduce the daily dose to the lowest level needed for maintenance of remission. Sometimes, it may be indicated to terminate haloperidol treatment gradually. Other forms of therapy (psychotherapy, occupational therapy/ergotherapie, social rehabilitation) should be instituted properly.