Haloperidol (antipsychotic): uses, effects and risks

One of the most commonly used drugs to treat schizophrenia.

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

All of them 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 psychological therapy.

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

What is haloperidol?

Haloperidol is a typical neuroleptic or antipsychotic belonging to the group of butyrophenones, central nervous system depressants with a sedative effect.These are central nervous system depressants with a sedative effect and act as very potent antagonists of the brain's dopaminergic receptors. This means that they prevent certain neurons from absorbing the neurotransmitter known as dopamine.

Haloperidol causes a potent motor sedation, which is useful in reducing symptoms of motor agitation and even pain.

This drug is mainly used for the treatment of schizophrenia and its positive symptoms, understood as those that could be considered as something that alters and excites the patient, in addition to the content of his thinking, speech or behavior: hallucinations, delusions, agitation, acceleration or distracted, prolix and shallow speech. Haloperidol, however, like most conventional antipsychotics, has no great effect on negative symptoms, has no great effect on negative symptoms (those that "take away" something from the patient (those that "take away" something from the patient, causing slowing, poverty of speech, anhedonia, or lack of logic).

Mechanism of action

Haloperidol acts through the blockade of dopamine receptors in the mesolimbic pathway, specifically the D2 receptors. suppression of positive symptoms (especially hallucinations and delusions) by reducing an excess of dopamine in this brain system. in this brain system.

However, haloperidol has a non-specific action, i.e. it does not block only the receptors of the mesolimbic pathway but has an effect on other pathways, which may cause unwanted side effects.

Side effects and risks

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

Specifically, its action on the nigrostriatal circuit causes movement-related effects such as slowing, incoordination, Muscle hypertonia or stiffness, or even tremors and restlessness.. Thus, it is possible that a bad reaction to this medication may provoke extrapyramidal syndrome, causing the above symptoms together with gestural inexpressiveness, static attitude, speech and writing difficulties and lack of reflexes. It is possible to control these symptoms with antiparkinsonian drugs. In addition, it can cause akathisia or constant motor restlessness, akinesia or lack of movement and tardive dyskinesias, involuntary movements of the facial muscles that imitate grimaces and chewing gestures, among others.

At the tuberoinfubular level, where haloperidol also acts although there is no alteration in psychotic episodes in this pathway, it increases prolactin production, which affects the reproductive system and 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 potent sedative effect may cause patients to reject it, since it reduces the level ofIt can also cause a decrease in the level of consciousness and therefore sometimes flatten affection and personal capacities.

Neuroleptic Malignant Syndrome

Although it is very infrequent, the most dangerous possible side effect is Neuroleptic Malignant Syndrome.. This very serious condition usually occurs soon after the start of treatment with the drug. It causes muscle stiffness, high fever, tachycardia, arrhythmia and can lead to death in 20% of cases. For causes such as these, it is essential to correctly titrate the administration of antipsychotics.

Pros and cons of their use

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

It should be remembered that these are possible side effects, which do not necessarily occur but should be evaluated and may cause a change in medication. However, haloperidol has a very potent action that can make it very useful in controlling certain symptoms, and can be used in psychotic disorders such as schizophrenia as well as in other problems and conditions.

Other indications

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

Due to its sedative properties, it has been used on occasions when the usual therapies are ineffective in cases of severe anxiety. It has also been used occasionally as an anesthetic and even to treat chronic pain. Similarly, it is used as a sedative in states of great motor agitation, as in cases of manic episodes or delirium tremens.

It also serves as an antiemetic, i.e. 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's syndrome, stuttering or Huntington's chorea in order to control involuntary spasmodic movements.

Contraindications of haloperidol

Haloperidol is contraindicated during pregnancy.. It will only be applied 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 necessary, it is necessary to consider the risks and the possibility of not applying natural lactation.

Due to its potent action, haloperidol is not recommended for patients who have to take a car or motorcycle, as the sedation and decreased mental alertness can have serious repercussions on driving ability.

Its potency also makes it inadvisable in cases of liver or kidney failure. Similarly, it can have serious repercussions if 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 alcohol or other drugs, or patients with previous lesions in the basal ganglia, it is also contraindicated, and its effects may be harmful.

Medication regimen

The intake 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 dosage in question will depend on the problem to be treated, the general guideline is as follows:

In acute phases of the disorder, a specific dose is recommended, sufficiently potent to achieve symptom control.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, and if not, change to another antipsychotic.

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

In the case of patients resistant to taking medication due to low disease awareness, a depot presentation of haloperidol can be applied, introducing a preparation that is injected intramuscularly, producing a slow release of the drug.

Bibliographical references:

• Azanza, J.R. (2006), Guía práctica de Farmacología del Sistema Nervioso Central. Madrid: Ed. Creación y diseño.

• 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 de Psicofarmacología. Madrid, Editorial Médica Panamericana.