Haloperidol (antipsychotic): uses, effects and risks

Diazepam, lorazepam, olanzapine, methylphenidate… Some of these names may be very familiar to read and hear in today's society.

They all are psychotropic drugs, substances that through certain mechanisms of action combat a series of specific symptoms such as anxiety, depression or hallucinations. They are used in many cases as the treatment of choice or as a first step to control the symptoms of a disorder to be treated. through therapy, as a way to keep symptoms under control or as a reinforcer of the effects of therapy psychological.

In this article we are going to talk about one of the psychotropic drugs used mainly in the treatment of psychotic symptoms, haloperidol.

What is haloperidol?

Haloperidol is a typical neuroleptic or antipsychotic within the group of butyrophenones, depressant agents of the central nervous system with sedative effect and that act as very potent antagonists of brain dopamine receptors. That means they prevent certain neurons from absorbing the neurotransmitter known as dopamine.

Haloperidol causes powerful motor sedation, which is useful to reduce symptoms of motor agitation and even in cases of pain.

This medicine is mainly used for the treatment of schizophrenia and its positive symptoms, these being understood as those that could be considered something that alters and excites the patient, added to the content of your thought, speech or behavior: hallucinations, delusions, agitation, acceleration or distracted speech, verbose and little deep. Haloperidol, however, like most conventional antipsychotics, has no great effect on negative symptoms (Those that "take" something from the patient, causing sluggishness, poor speech, anhedonia or lack of logic).

Mechanism of action

Haloperidol acts by blocking dopamine receptors in the mesolimbic pathway, specifically D2-type receptors, a fact that involves the suppression of positive symptoms (especially hallucinations and delusions) by reducing excess dopamine in this brain system.

However, haloperidol has a non-specific action, that is, it does not block only the receptors of the mesolimbic pathway but has an effect on other pathways, which can cause side effects not desired.

Side effects and risks

Like most psychoactive drugs, haloperidol has a number of side symptoms or possible adverse effects. Also, like most typical antipsychotics, the effect of action on dopamine blockade has potential repercussions on different systems.

Specifically, its action on the nigrostriatal circuit causes movement-related effects such as muscle sluggishness, incoordination, hypertonia or stiffness, or even tremors and restlessness. Thus, it is possible that a bad reaction to this medication can cause extrapyramidal syndrome, causing the previous symptoms along with gestural expressionlessness, static attitude, speech and writing difficulties and lack of reflexes. These symptoms can be controlled with antiparkinsons. In addition, it can cause akathisia or constant motor restlessness, akinesia or lack of movement and dyskinesias late, involuntary movements of the facial muscles that imitate grimacing and chewing gestures, among others.

At the tuberoinfubular level, where haloperidol also acts despite the fact that there is no alteration in psychotic episodes in this pathway, it increases the production of prolactin, which affects the reproductive system, which can cause gynecomastia (growth of breasts in men), galactorrhea or emission of milk from the breasts (even in men) and the absence of menstruation or amenorrhea

Apart from this, its powerful sedative effect can lead to rejection by patients, since it decreases the level of consciousness and therefore sometimes flattens affection and personal capacities.

Neuroleptic Malignant Syndrome

Although it is very rare, the most dangerous possible side effect is Neuroleptic Malignant Syndrome. This very serious condition usually occurs shortly after starting treatment with the drug. It causes muscle stiffness, high fever, tachycardia, arrhythmia and can lead to death in 20% of cases. For reasons like this, it is essential to carry out a correct graduation of the administration of antipsychotics.

Pros and cons of its use

Although these antipsychotics tend to have greater side effects than the atypical ones, since the latter only act at the mesolimbic-mesocortical, while the typical ones such as haloperidol also affect the nigrostriatal system, they continue to be applied in cases with resistance to atypical neuroleptics. As already mentioned, its function is based on the treatment of positive symptoms, causing little improvement in negative symptoms.

It should be remembered that these are possible side effects, that they do not have to occur but that they must be considered and that they can cause a change in medication. However, haloperidol has a very powerful action that can make it very useful to control certain symptoms, being able to be used both in psychotic disorders such as schizophrenia and in other problems and terms.

Other indications

Apart from its application in schizophrenia, haloperidol can be used in a large number of problems due to its various properties. This medicine it is very useful in the treatment of acute psychoses and other psychiatric disorders.

Due to its sedative properties, it has been used on occasions when the usual therapies have no effect on cases of severe anxiety. It has also been used occasionally as an anesthetic and even to treat chronic pain. In the same way, it is used as a sedative in states of great motor agitation, such as in cases of manic episodes or delirium tremens.

It also serves as an antiemetic, that is, as a mechanism to prevent vomiting in those cases or syndromes in which the cessation of the vomiting process is necessary.

It is also used for the treatment of tics, Tourette syndrome, stuttering or Huntington's chorea in order to control involuntary jerking movements.

Contraindications of haloperidol

Haloperidol is contraindicated during pregnancy. It will only apply in these cases if there are no other alternatives. It is also contraindicated during lactation since it is excreted through breast milk. If the use of haloperidol is required, it is necessary to consider the risks and the possibility of not applying breastfeeding.

Due to its powerful action, haloperidol is not recommended for patients who have to drive or motorcycle, since sedation and decreased mental alertness can have serious repercussions on the ability to driving.

Its potency also makes it not recommended in cases of liver or kidney failure. In the same way, it can have serious repercussions when mixed with barbiturates, analgesics, morphine, antihistamines or benzodiazepines, among others.

Likewise, in patients with hypersensitivity to antipsychotics, cases of coma or depression of the nervous system due to the consumption of alcohol and other drugs, or patients with previous lesions in the basal ganglia It is also contraindicated, and its effects may be harmful.

Medication schedule

The taking of haloperidol, as well as that of any antipsychotic, must be regulated with great precision in order to avoid or minimize the existence of dangerous secondary symptoms. Although the dose in question will depend on the problem to be treated, the general guideline will be as follows:

In acute phases of the disorder, a certain dose is recommended, powerful enough to control symptoms., repeating the same dose until the outbreak or symptoms subside.

It is advisable to wait about six weeks in order to determine if the drug has the expected effects, being able to change to another antipsychotic in the negative case.

Once the acute phase of the disorder is over, the dose applied will be reduced as the symptoms until reaching a maintenance dose, which it is recommended to maintain in order to avoid relapses.

For patients resistant to taking medication due to low awareness of disease, a presentation may apply depot of haloperidol, introducing a preparation that is injected intramuscularly, producing a slow release of the medicine.

Bibliographic references:

• Azanza, J.R. (2006), Practical Guide to Pharmacology of the Central Nervous System. Madrid: Ed. Creation and design.

• Franco-Bronson, K. & Gajwani, P. (1999). Hypotension associated with intravenous haloperidol and imipenem. J Clin Psychopharmacol.; 19 (5): pp. 480 - 481.

• Salazar, M.; Peralta, C.; Pastor, J. (2006). Manual of Psychopharmacology. Madrid, Editorial Médica Panamericana.