Types of antipsychotics (or neuroleptics)

The There is a great diversity of theories and hypotheses about psychotic disorders, their causes and how to treat them. These disorders are a great detriment to those who suffer them, and cause great anguish both for the person himself and for those around him. They interfere with cognitive abilities, social relationships and the emotional sphere, altering contact with reality. Being disorders that limit the normative functioning of the human being, its treatment is essential.

Based on the research carried out, from a point of view of the psychotropic drugs Various substances and active ingredients have been developed that can help treat these types of problems. It is about the different types of antipsychotics or neuroleptics.

Psychotic disorders

For most people the word schizophrenia it is not something unknown. It refers to one of the main and best known psychotic disorders, a group of disorders characterized by the presence of perceptions, ideas and behaviors far from the normative, usually with some loss of contact with reality.

These types of disorders usually involve two types of symptoms: positive, which cause or add something to behavior, perception or flow of habitual thought, and the negative ones as those symptoms that flatten and produce a deficit in the psychosocial-emotional state of the suffers.

The most typical and well-known examples of the symptoms of psychotic disorders are the presence of abnormal perceptions or hallucinations and that of more or less structured belief systems, the so-called delusions. Although the negative symptoms are less visible, they stand out loss of logic and coherence in thought, poverty in language and poverty of thought or praise.

Let us now focus on one of the forms of treatment, the pharmacological one, reviewing the different substances that are used in the presence of psychotic symptoms.

Mechanism of action of neuroleptics

Drugs dedicated to fighting the symptoms of psychotic disorders are called antipsychotics or neuroleptics. Formerly known as major tranquilizers, this type of drug successfully fights typical symptoms, especially positive ones.

This type of psychotropic drug focuses mainly on the neurotransmitter known as dopamine, due to the high level of relationship found between this hormone and psychotic symptoms.

Specifically, it has been contemplated that an excess of dopamine in the mesolimbic pathway causes the presence of positive symptoms such as hallucinations and delusions, while a dopaminergic deficit at the mesocortical level is the most probable cause of negative symptoms like poverty of thought and praise. That is why the mechanism of action of the drugs that treat these problems will focus on working with dopamine at the level of its synthesis, reuptake and transmission. However, between the different types of antipsychotics there are differences and nuances in the way they work, as we will see.

In addition to in the treatment of psychotic disorders, some neuroleptics have been used before another type of problems, such as some motor, affective or personality disorders (for example, in the case of borderline disorder).

Types of antipsychotics

Traditionally, antipsychotics or neuroleptics have been classified into two large groups, the classic or typical neuroleptics and the atypical ones.

1. Classic or typical antipsychotics

Discovered by chance in the 1950s, typical antipsychotics are those with which pharmacological treatment of psychotic disorders was started. This type of medication exerts its action by blocking the dopamine D2 receptors of the pathway mesolimbic, reducing the excess of this hormone in the system and causing the cessation of symptoms positive.

Within this group of antipsychotics we find some as well known as haloperidol, chlorpromazine or levomepromazine, along with others such as pimozide, zuclopenthixol or fluphenazine. They can be administered both directly and in depot presentation, in which the substance is injected into the muscle in crystallized form of a way that is released slowly over time (in cases where there is little willingness to take medication or little control over the follow-up of the treatment).

However, despite their great utility, typical neuroleptics are nonspecific, so dopamine receptor blockade does not only occur in the mesolimbic pathway. This causes other pathways that also depend on dopamine to be altered., also affecting the mesocortical pathway, from which negative symptoms appear to arise due to a dopamine deficit. Because classical neuroleptics work by blocking their uptake, typical antipsychotics they have practically no effect on negative symptoms, and may even worsen them.

Adverse effects

In addition to this, other pathways such as the nigrostriatal and tuberoinfundibular pathways, which in disorders psychotics do not have to be altered in themselves, dopamine uptake is also inhibited, with what adverse effects may arise in the form of movement disorders such as akathisia, parkinsonian syndrome and dyskinesia, or sexual disorders such as amenorrhea or gynecomastia. These symptoms are not only bothersome, but they can cause neuroleptic malignant syndrome, which could lead to death. Therefore, it is necessary to carefully guide the consumption of these drugs, following the prescriptions of professionals and being able to change the antipsychotic in order to reduce the discomfort and effects adverse.

It is for this reason that subsequent research focused on investigating and make other antipsychotics that have a positive effect on negative symptoms and do not produce as many side effects. This is not to say that typical antipsychotics are no longer used, since they are very effective and the symptoms Adverse drugs can be controlled with other medications (antiparkinsons for motor problems, for example).

2. Atypical antipsychotics

Taking into account the little effect of conventional antipsychotics on negative symptoms and the high number of unwanted side effects that they entail, subsequent research has tried to create new substances that make up for the deficiencies of this type of neuroleptics, creating safer drugs and effective. These safer drugs have been classified as atypical antipsychotics or neuroleptics.

Within the atypical antipsychotics we find substances of various families and compositions, so depending on which one is used, it will have a greater or lesser effect on various problems. The main drugs that fall into this category are clozapine, olanzapine, risperidone, sulpiride, quetiapine, and ziprasidone.

Differences from classical neuroleptics

As with conventional drugs, atypical antipsychotics work by blocking dopamine D2 receptors, with which in the mesolimbic pathway they would have an inhibitory effect on this neurotransmitter, which causes the cessation of positive symptoms. However, in addition to this, atypical antipsychotics have an effect on serotonin, also producing an antagonistic effect with respect to it.

It is necessary to take into account that serotonin acts as an inhibitor of dopamine release. Therefore, the effect that atypical antipsychotics have on the tuberoinfundibular and nigrostriatal pathways (which would be affected by a conventional neuroleptic) generates an interaction between dopamine and serotonin that would leave the level of dopamine equal to or close to what would be normal. In other words, the presence of possible adverse effects is greatly reduced.

However, since there are more serotonin receptors than dopamine receptors in the cerebral cortex, the fact that inhibiting serotonin causes an increase in dopamine release as it stops stopping its release. That is to say that despite the fact that part of its operation blocks the release of dopamine, the fact that a release inhibitor that is much more present and widespread causes the total dopamine level to be higher. For this reason, Atypical antipsychotics do have an effect on negative symptoms, by increasing the crude dopamine level in the mesocortical pathway.

With all this, atypical neuroleptics represent an advance that produces improvement in both positive and negative symptoms and they generate fewer adverse effects (although they do have some).

Risks and side effects of taking antipsychotics

We have briefly commented that taking antipsychotics can cause different undesirable side effects, some especially dangerous. This phenomenon occurs with all psychotropic drugs, since each body is different and the exact way in which the active principle will interact with the body is not known exactly. That is why it is essential to have medical supervision, to detect these problems in time and propose alternatives.

These effects can be controlled by taking other medications or changing the neuroleptic, having to evaluate the possible effects and the appearance of adverse effects after administration. Some of the main risks and side effects of the different types of antipsychotics are as follows.

1. Motor symptoms

One of the pathways affected secondarily by taking antipsychotics is the nigrostria, which is linked to motor control.

In this way, extrapyramidal syndrome is common, in which symptoms such as Parkinson's tremors appear, the appearance of involuntary movements in tardive dyskinesia, the disappearance of spontaneous movements of akinesia or motor restlessness of the akathisia. These symptoms occur mainly when taking conventional or typical antipsychotics, and their appearance with atypical antipsychotics is not frequent.

2. Sexual symptoms

Taking certain neuroleptics can cause different sexual symptoms, generally due to involvement of the tuberoinfundibular tract (especially in the hypophysis). Among these types of symptoms, the cessation of menstrual flow or amenorrhea stands out, as well as galactorrhea or emission of milk by the breasts regardless of sex and gynecomastia or breast enlargement, also regardless of the sex of the patient. Although in general they only occur with typical antipsychotics, there are some cases with certain atypicals, such as risperidone.

3. Sedation

As we have seen, one of the original names for antipsychotics is major tranquilizers. This term was not given by chance, and is that taking antipsychotics produces a sedative effect that can be more or less powerful.

4. Neuroleptic malignant syndrome

This syndrome is one of the most serious side effects that taking antipsychotics can cause, which can lead to coma or even death. It is characterized because the individual suffers from tachycardias, arrhythmias, high fever, muscle stiffness and loss of consciousness.to. However, it is a very rare syndrome.

5. Agranulocytosis

Described in the case of clozapine, this possible side effect takes on some seriousness as it causes the levels of red and white blood cells to spiral out of control. It can be fatal, so blood tests are required as a control method.

6. Other symptoms

Apart from the above symptoms, it is possible to find other problems such as weight gain, excessive salivation, rapid heart rate, or dizziness.

Bibliographic references:

• Azanza, J.R. (2006), Practical Guide to Pharmacology of the Central Nervous System. Madrid: Ed. Creation and design.
• Gómez, M. (2012). Psychobiology. CEDE Preparation Manual PIR. 12. CEDE: Madrid.
• Keefe, R.S., Silva, S.G., Perkins, D.O.; Lieberman, J.A. (1999). The effects of atypical antipsychotic drugs on neurocognitive impairment in schizophrenia: a review and meta-analysis. Schizophrenia Bulletin. 25 (2): pp. 201 - 22.
• Miyamoto, S.; Miyake, N.; Jarskog, L.F.; Fleischhacker, W.W.; Lieberman, J.A. (2012). Pharmacological treatment of schizophrenia: a critical review of the pharmacology and clinical effects of current and future therapeutic agents. Molecular Psychiatry. 17 (12): pp. 1206 - 1227.
• Salazar, M.; Peralta, C.; Pastor, J. (2011). Manual of Psychopharmacology. Madrid, Editorial Médica Panamericana.