As we all know, the use of substances with properties that contribute to improving the symptoms of a disease or disorder is a key element in medicine, being used to return the organism to its state of natural balance.
In the case of psychological disorders, the presence of very diverse problems has generated research into multiple treatment options, including pharmacological treatment.
What kinds of psychotropic drugs exist and what are they used for?
The fact that there are a large number of different symptoms and disorders has led to a wide variety of drugs to treat them, divided into different types of psychotropic drugs.
None of these categories is, in itself, better than the rest, and its utility will depend on each case. However, clinical psychologists and psychiatrists must know them all to offer the best possible treatment to their patients.
1. Neuroleptics / antipsychotics
Used primarily as a method of controlling psychotic crises, this group of psychotropic drugs were formerly called major tranquilizers due to the level of sedation that their early versions caused. There are different groups within this conglomerate, exerting an effect mainly in the transmission of dopamine in distant brain regions.
Among neuroleptics we can find:
1.1. Classic / typical antipsychotics
The mechanism of action of these substances is based on the blockade of dopamine receptors (specifically the D2 receptors) of the mesolimbic pathway, blockade that causes a cessation of the positive symptoms of schizophrenia and psychotic disorders (hallucinations, delusions, etc.).
However, the performance of this type of drugs does not only occur in the mesolimbic circuit, but also affects the other dopaminergic pathways, which can cause side effects in different facets such as movement (for example tremors, tardive dyskinesias, restlessness or low spontaneity ) or reproduction (milk emission by the breasts regardless of sex or amenorrhea among others).
In addition, these drugs have very little effect on negative symptoms (lack of logic, poor language, motor and mental slowness), and their effect is practically non-existent in this regard. Within this group you can find chlorpromazine, haloperidol or pimozide, among others.
1.2. Atypical antipsychotics
In order to produce an improvement also in the symptoms of negative type and to reduce the side effects due to the affectation of other routes, the atypical antipsychotics were synthesized. This type of neuroleptic acts by blocking dopamine and serotonin, achieving with blockade of the second eliminate the side effects of blocking the first.
Likewise, given the greater number of serotonin receptors in the cortex and the fact that it acts as an inhibitor of dopamine, the inhibition of dopamine causes an increase in the performance of dopamine in mesocortical areas, which causes the improvement of the negative symptoms. In spite of everything, they can present some side effects such as hypotension, tachycardia, dizziness or sedation. In the case of clozapine there is also the risk of agranulocytosis, alteration in the red and white blood cell count that can be fatal if left unchecked.
Within this group we find clozapine, risperidone, olanzapine, quetiapine, sulpiride and ziprasidone. Since they belong to different families, they can have greater or lesser effect in certain alterations, functioning not only for psychotic disorders but for others such as tic disorders, autism, OCD and mood disorders.
2. Anxiolytics and Hypnotic-sedatives
The presence of anxiety problems is a frequent phenomenon in today’s society, being the most frequent type of disorders. In order to combat it, anxiolytics have been generated.
This type of psychopharmaceutical acts by exerting a depressant effect on the nervous system, causing a decrease in the level of activity of the person. They generally act on the GABA hormone, enhancing its inhibitory action. Some types of psychotropic drugs included in this classification are used as sedatives, to facilitate sleep, while others are used to simply achieve physical and mental relaxation.
Within this group we can find the following subtypes:
This group of psychotropic drugs were the most popular until the discovery of benzodiazepines when it comes to treating anxiety. However, the risk of these drugs is that they have a high capacity to cause dependence, not being infrequent poisoning by overdose and even death. Also in the long term could cause neurological damage.
The discovery of this type of psychotropic drugs greatly helped the treatment of anxiety disorders, presenting a series of benefits that have now made them the most marketed psychotropic drugs for anxiety. Specifically, in addition to an immediate effect they present less risk to health than barbiturates, producing fewer side effects, being less addictive and causing less sedation.
In addition to its anxiolytic effect, benzodiazepines are used as sedatives and even as anticonvulsants. However, in long treatments they can generate dependency as well as abstinence after the cessation of their consumption, so that they have to follow the medical prescriptions with rigor and correctly schedule their intake and withdrawal.
It is a type of substance that favors the inhibitory function of GABA, being indirect agonists of this neurotransmitter. Although they are distributed non-specifically throughout the brain, the cortex and the limbic system are where they are most active.
Within benzodiazepines there are also different types, depending on whether they have long action (they require more time to take effect but have a much longer duration than the rest), intermediate or short (immediate action and short duration, ideal for crisis of panic), that is, depending on the average life of the substance in the body.
Some examples of benzodiazepines are the well-known triazolam, alprazolam, lorazepam, clonazepam or bromazepam (better known by its trade name, Lexatin).
2.3. Hypnotic-short-acting sedatives.
Zaleplom, Zolpidem and Zopiclona are the names of three drugs that, like benzodiazepines, act as GABA agonists. The main difference with benzodiazepines is that while they act on all GABA receptors, hypnotics only act on receptors linked to sleep, not affecting cognition, memory or muscle function.
This psychotropic drug is used especially in cases of generalized anxiety disorder. Its mechanism of action is focused on serotonin, being an agonist of it. In this way it is one of the few anxiolytics that have no relation to GABA receptors. It does not cause dependency or abstinence. However, it has the disadvantage that the effect of this substance may take more than a week to take effect.
After anxiety disorders, mood disorders are some of the most prevalent in the general population, especially in the case of depressions. To treat this problem we have this class of psychotropic drugs, which propose different alternatives:
3.1. Inhibitors of the enzyme MonoAmino Oxidase (IMAOS)
The first antidepressants to be discovered, this type of psychotropic drugs was found accidentally while looking for a remedy against tuberculosis. Its functioning is based on the inhibition of the monoamine oxidase enzyme, which is normally responsible for eliminating the excess of monoamines (specifically serotonin, dopamine and noradrenaline).
This type of antidepressant tends not to be used as the treatment of choice, reserving for cases that do not respond to other drugs. The reason for this is that they present a high risk of hypertensive crisis, requiring a thorough control of its administration and having to control that certain foods containing tyramine or protein rich (such as chocolate, dried fish, cheese, coffee) are not consumed. , beer…). It also has other side effects such as possible anorgasmia or weight gain.
Within the MAOIs can be found Irreversible and non-selective (its function is to completely destroy the MAO enzyme) and Reversible and Selective that only inhibit the function of the MAO without destroying it, so if there is a real excess of monoamines the enzyme could function. Examples of MAOIs would be Isocarboxacid and Moclobemide.
3.2. Tricyclic and tetracyclic
Found while researching the creation of neuroleptics, this type of psychotropic drug was until the discovery of the SSRIs most used for the treatment of depression. Its name comes from its structure in the form of rings. Its action is based on inhibiting the reuptake of both serotonin and noradrenaline, with which these hormones remain for longer in the synaptic space having a longer effect. The effects of these drugs begin to be noticed after two or three weeks.
However, apart from its effect on serotonin and noradrenaline also affect other hormones, being antagonists of acetylcholine, histamine and blocking some noradrenaline receptors. Therefore, they can cause antihistaminic and anticholinergic effects (dry mouth, constipation, blurred vision …). They can also cause death by overdose, which must be regulated with special caution.
Some famous tricyclic antidepressants are imipramine (used in addition to depression in anxiety disorders and parasomnias) or clomipramine (also used as a treatment in OCD and anorexia).
3.3. Specific Inhibitors of Serotonin Reuptake (SSRI)
SSRIs are a type of psychotropic drug that is characterized by, as its name indicates, inhibiting the reuptake of serotonin in a specific way. That is, prevent serotonin from being reabsorbed so that it is more available and its presence in the brain is prolonged, without affecting other neurotransmitters.
In this group of psychotropic drugs we can find fluoxetine (known as Prozac), paroxetine, sertraline, fluvoxamine, citalopram and escitalopram.
It is the type of antidepressant with a higher level of safety and fewer side effects, being treatment of first choice in many cases, and not only in the face of major depression but also in other disorders. Specifically, they are pharmacological treatment of choice in OCD, as well as in eating disorders (fluoxetine is the most effective in cases of bulimia).
3.4. Selective Inhibitors of Noradrenaline Reuptake
Like the SSRIs, the action of this type of drug is based on inhibiting the reuptake of a hormone so that it has a greater presence in neuronal synapses, being in this case noradrenaline the neurotransmitter in question. Reboxetine is the most relevant drug in this sense.
3.5. Dual Inhibitors of Reuptake of Serotonin and Noradrenaline
It acts in the same way as tricyclics, but with the difference that they only affect the neurotransmitters in which it is intended to act. That is, they are specific, which eliminates a large part of the side effects. The example of a drug of this type available at present is venlafaxine.
4. Mood stabilizers / Eutimizers
Another major disorder of mood is bipolar disorder. In order to maintain a balanced and stable state of mind, there are also two basic types of psychotropic drugs available:
4.1. Lithium salts
Although it is proposed that it produces an alteration of the G protein that modulates the transmission of messages in neuronal synapses, the mechanism of action of this type of psychotropic drug is not yet fully known. In spite of the exact lack of knowledge of why, this medicine has shown a high efficacy in treating manic episodes and keeping the mood stable.
However, it has the disadvantage that the difference between the amount necessary to produce a mood stabilizing effect and that necessary for intoxication is very close, being essential the control by means of analysis of the level of lithium in blood. It can also produce some side effects such as diarrhea, acne, tremors, hair loss or cognitive loss, with which there may be some resistance to treatment.
Although these drugs were developed to control seizures in cases of epilepsy, studies have shown that they are also highly effective in treating bipolar disorder.
Its operation is based on favoring the action of GABA and reducing that of glutamate. Mainly, valproic acid, carbamazepine and topiramate are used.