Types Of Antipsychotics (or Neuroleptics) And Their Characteristics
There is a great diversity of theories and hypotheses about psychotic disorders, their causes and the way to treat them. These disorders cause great harm to those who suffer from them, and produce strong anguish for both the person themselves and those around them. 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, treatment is essential
Based on the research carried out, several substances and active ingredients have been developed from the side of psychotropic drugs that can help treat this type of problems. These are the different types of antipsychotics or neuroleptics
For most people the word schizophrenia 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 ones, which cause or add something to the habitual behavior, perception or flow of thought, and negative ones, such as those symptoms that flatten and produce a deficit in the psychosocial-emotional state of the sufferer.
The most typical and well-known examples of the symptoms of psychotic disorders are the presence of abnormal perceptions or hallucinations and more or less structured belief systems, known as delusions. Although the negative symptoms are less visible, they stand out the loss of logic and coherence in thought, poverty in language and poverty of thought or alogia.
Let us now focus on one of the forms of treatment, pharmacological, reviewing the different substances that are used in the presence of psychotic symptoms.
Mechanism of action of neuroleptics
Drugs dedicated to combating the symptoms of psychotic disorders are called antipsychotics or neuroleptics. Formerly known as major tranquilizers this type of drug very successfully combats the typical symptoms, especially the 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 likely cause of negative symptoms like poverty of thought and alogy. This 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 the treatment of psychotic disorders, some neuroleptics have been used for other types 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, classic or typical neuroleptics and atypical ones.
1. Classic or typical antipsychotics
Discovered by chance in the 1950s, Typical antipsychotics are those with which the pharmacological treatment of psychotic disorders began This type of medication acts by blocking the dopamine D2 receptors of the mesolimbic pathway, reducing the excess of this hormone in the system and causing the cessation of positive symptoms.
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 so that it is slowly released over time (in cases where there is little desire to take medication or little control). of treatment follow-up).
However, despite their great usefulness, typical neuroleptics are nonspecific, so the blockade of dopaminergic receptors 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 apparently arise due to a dopamine deficiency. Because classic neuroleptics act 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 psychotic disorders do not have to be altered per se, also see dopamine uptake inhibited, thus 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 annoying, but can cause neuroleptic malignant syndrome, which could lead to death. For this reason, it is necessary to carefully schedule the consumption of these drugs, following the prescriptions of professionals and being able to change the antipsychotic in order to reduce discomfort and adverse effects.
It is for this reason that subsequent research focused on investigating and develop other antipsychotics that would have a positive effect on negative symptoms and would not produce as many side effects This does not mean that typical antipsychotics have stopped being used, since they are very effective and adverse symptoms can be controlled with other medication (antiparkinsonian in the case of motor problems, for example).
Taking into account the little effect of conventional antipsychotics on negative symptoms and the high number of unwanted side effects they entail, subsequent research has attempted to create new substances that make up for the deficiencies of this type of neuroleptics, creating safer and more effective drugs. effective. These safer drugs have been classified as antipsychotics or atypical neuroleptics
Within atypical antipsychotics we find substances from 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 They are clozapine, olanzapine, risperidone, sulpiride, quetiapine and ziprasidone
Differences from classic neuroleptics
As with conventional antipsychotics, atypical antipsychotics work by blocking dopamine D2 receptors, which would have an inhibitory effect on this neurotransmitter in the mesolimbic pathway, which causes the cessation of positive symptoms. However, In addition, atypical antipsychotics have an effect on serotonin also producing an antagonistic effect with respect to it.
It is necessary to keep in mind that serotonin acts as an inhibitor of the release of dopamine. Therefore, the effect that atypical antipsychotics cause 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 dopamine level equal to or close to what would be normal. In other words, the presence of possible adverse effects is greatly reduced
However, given that there are more serotonin than dopamine receptors in the cerebral cortex, inhibiting serotonin causes an increase in the release of dopamine as it stops stopping its release. That is to say that although part of its operation blocks the release of dopamine, the fact that an inhibitor of its release that is much more present and widespread is inhibited makes the total level of dopamine higher. For this reason, atypical antipsychotics do have an effect on negative symptoms, by increasing the raw level of dopamine in the mesocortical pathway.
With all this, atypical neuroleptics They represent an advance that produces improvement in both positive and negative symptoms and they generate fewer adverse effects (although they 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 it is not known exactly how the active ingredient will interact with the body. This 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 neuroleptics, and the possible effects and the appearance of adverse effects after administration must be evaluated. Some of the main risks and side effects of different types of antipsychotics are as follows.
1. Motor symptoms
One of the pathways affected secondarily by taking antipsychotics is the nigrostriatum, which is linked to motor control.
Thus, extrapyramidal syndrome is common, in which symptoms appear such as Parkinson-type tremors, the appearance of involuntary movements in tardive dyskinesia, the disappearance of spontaneous movements in akinesia or the motor restlessness in akathisia. These symptoms occur mainly when taking conventional or typical antipsychotics, and their appearance is not frequent with atypical antipsychotics.
2. Sexual symptoms
Taking certain neuroleptics It can cause different sexual symptoms, generally due to the involvement of the tuberoinfundibular tract (especially in the pituitary gland). Within this type of symptoms, the cessation of menstrual flow or amenorrhea stands out, as well as galactorrhea or the emission of milk from the breasts regardless of sex and gynecomastia or breast growth, also regardless of the sex of the patient. Although in general they only occur with typical antipsychotics, there are some cases with certain atypical ones, such as risperidone
3. Sedation
As we have seen, one of the original names of antipsychotics is major tranquilizers. This term was not given by chance and taking antipsychotics produces a sedation 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, and can lead the patient to coma or even death. It is characterized by the individual suffering from tachycardia, arrhythmias, high fever, muscle rigidity and loss of consciousness to. However, it is a very rare syndrome.
5. Agranulocytosis
Described in the case of clozapine, this possible side effect is somewhat serious as it causes the levels of red and white blood cells to become uncontrolled. It can be lethal, so it is necessary to have blood tests as a control method.
6. Other symptoms
Apart from the previous symptoms, it is possible to encounter other problems such as weight gain, excessive salivation, tachycardia, or dizziness
