As we all know, the use of substances with properties that help improve the symptoms of a disease or disorder is a key element in medicine, used to return the body to its natural state of balance.

In the case of psychological disorders, the presence of very diverse problems has led to the investigation of multiple treatment options, including pharmacology.

What kinds of psychopharmaceuticals are there and what are they used for?

The fact that there are many 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 their usefulness will depend on each case. However, clinical psychologists and psychiatrists should know them all to offer the best possible treatment to their patients .

Let’s proceed to see the different types of psychopharmaceuticals that exist in reality.

Neuroleptics/antipsychotics

Used mainly as a method of controlling psychotic episodes , this group of psychopharmaceuticals was formerly called major tranquilizers due to the level of sedation that their first versions caused. There are different groups within this conglomerate, exerting an effect mainly on the transmission of dopamine in distant brain regions.

Inside the neuroleptics we can find:

1.1. Classical/typical antipsychotics

The mechanism of action of these substances is based on the blocking of the dopamine receptors (specifically the D2 receptors) of the mesolimbic pathway, a blockage that causes a cessation of the positive symptoms of schizophrenia and psychotic disorders (hallucinations, delusions, etc.).

However, the action of this type of medication does not only occur in the mesolimbic circuit, but also affects the rest of the dopaminergic pathways, and can cause side effects in different facets such as movement (for example tremors, late dyskinesias, restlessness or low spontaneity) or reproduction (release of milk from the breasts regardless of sex or amenorrhea, among others).

Furthermore, these drugs have very little effect on the negative symptoms (lack of logic, poor language, motor and mental slowness), their effect being practically non-existent in this respect. Within this group we can find chlorpromazine, haloperidol or pimozide, among others.

1.2. Atypical antipsychotics

Atypical antipsychotics were synthesized in order to produce an improvement in negative symptoms and to reduce side effects due to the involvement of other pathways. This type of neuroleptic acts by blocking dopamine and serotonin , managing to eliminate the side effects of the blockage of the latter.

Also, given the increased number of serotonin receptors in the cortex and the fact that the cortex acts as a dopamine inhibitor, inhibition of dopamine causes an increase in dopamine performance in the mesocortical areas, which results in the improvement of negative symptoms. However, some side effects such as hypotension, tachycardia, dizziness or sedation may occur. In the case of clozapine there is also the risk of agranulocytosis, an alteration in the red and white blood cell count that can be fatal if not controlled.

Within this group we find clozapine, risperidone, olanzapine, quetiapine, sulpiride and ziprasidone. Since they belong to different families, they may have more or less effect on certain disorders, working not only for psychotic disorders but also for others such as tic disorders, autism, OCD and mood disorders.

2. Anxiolytics and sedative-hypnotics

The presence of anxiety problems is a frequent phenomenon in today’s society , being the most frequent type of disorders. With the aim of combating it, anxiolytics have been generated.

This type of psychopharmaceutical acts by exerting a depressive effect on the nervous system, causing a decrease in the person’s activity level. They generally act on the hormone GABA, enhancing its inhibitory action. Some types of psychopharmaceuticals 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:

2.1. Barbiturates

This group of psychopharmaceuticals was the most popular until the discovery of benzodiazepines for treating anxiety. However, the risk of these drugs is that they have a high capacity to cause dependence, with intoxication by overdose and even death being not uncommon. They may also cause long-term neurological damage.

2.2. Benzodiazepines

The discovery of this type of psychotropic drugs helped greatly in the treatment of anxiety disorders, presenting a series of benefits that have made them the most widely marketed psychotropic drugs for anxiety today. Specifically, in addition to an immediate effect, they present less health risk than barbiturates, producing fewer side effects, being less addictive and causing less sedation.

Besides their anxiolytic effect, benzodiazepines are used as sedatives and even as anticonvulsants . However, in long treatments they can generate dependence as well as abstinence after stopping their consumption, so the medical prescriptions must be followed rigorously and their taking and withdrawal must be correctly regulated.

It is a type of substance that favors the inhibitory function of GABA, being indirect agonists of this neurotransmitter. Although they are unspecifically distributed throughout the brain, the cortex and the limbic system is where they show the greatest performance.

Within the benzodiazepines there are also various types, depending on whether they have a long action (they need more time to take effect but last much longer than the rest), intermediate or short action (immediate and short-term action, ideal for panic attacks), i.e. depending on the half-life of the substance in the body.

Examples of benzodiazepines are the well-known triazolam, alprazolam, lorazepam, clonacepam or bromazepam (better known by its trade name, Lexatin).

2.3. Short-acting sedative-hypnotics

Zaleplom, Zolpidem and Zopiclone 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 sleep-linked receptors, not affecting cognition, memory or muscle function.

2.4. Buspirone

This psychoactive drug is used especially in cases of generalized anxiety disorder. Its mechanism of action is focused on serotonin, being an agonist of this one. Thus, it is one of the few anxiolytic drugs that are not related to GABA receptors. It does not cause either dependence or abstinence. However, it has the disadvantage that the effect of this substance can take more than a week to take effect.

3. Antidepressants

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 pose different alternatives. However, the exact mechanism by which they are useful for treating certain disorders is not yet known, and they are not only useful for mood disorders.

In any case, as with any of the other types of psychotropic drugs, antidepressants can only be used on medical advice. The fact that they act primarily on mood does not mean that their influence on the brain is without considerable risk.

3.1. Monoamine Oxidase Inhibitors (MAOIs)

The first antidepressants to be discovered, this type of psychoactive drug was accidentally found while looking for a remedy for tuberculosis . Its functioning is based on the inhibition of the enzyme monoamine oxidase, which is normally responsible for eliminating excess monoamine (specifically serotonin, dopamine and noradrenaline).

This type of antidepressant tends not to be used as a treatment of choice, being reserved for cases that do not respond to other drugs. The reason for this is that they present a high risk of hypertensive crisis, requiring exhaustive control of their administration and controlling that certain foods containing tyramine or rich in protein (such as chocolate, dried fish, cheese, coffee, beer…) are not consumed. It also presents other side effects such as possible anorgasmia or weight gain.

Besides their anxiolytic effect, benzodiazepines are used as sedatives and even as anticonvulsants .
However, in long treatments they can generate dependence as well as abstinence after stopping their consumption, so the medical prescriptions must be followed rigorously and their taking and withdrawal must be correctly regulated.

It is a type of substance that favors the inhibitory function of GABA, being indirect agonists of this neurotransmitter. Although they are unspecifically distributed throughout the brain, the cortex and the limbic system is where they show the greatest performance.

Within the benzodiazepines there are also various types, depending on whether they have a long action (they need more time to take effect but last much longer than the rest), intermediate or short action (immediate and short-term action, ideal for panic attacks), i.e. depending on the half-life of the substance in the body.

Examples of benzodiazepines are the well-known triazolam, alprazolam, lorazepam, clonacepam or bromazepam (better known by its trade name, Lexatin).

2.3. Short-acting sedative-hypnotics

Zaleplom, Zolpidem and Zopiclone 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 sleep-linked receptors, not affecting cognition, memory or muscle function.

SSRIs are a type of psychodrug that is characterized by, as its name indicates, specifically inhibiting the reuptake of serotonin . That is, preventing serotonin from being reabsorbed so that it becomes more available and its presence in the brain is prolonged, without affecting other neurotransmitters.

In this group of psychopharmaceuticals we find fluoxetine (the well-known Prozac), paroxetine, sertraline, fluvoxamine, citalopram and escitalopram.

It is the type of antidepressant with the highest level of safety and the least side effects, being the first choice treatment in many cases, and not only for major depression but also for other disorders. Specifically, they are the pharmacological treatment of choice in OCD, as well as in eating disorders (fluoxetine is the most effective in cases of bulimia)

3.4. Selective Noradrenaline Reuptake Inhibitors

As with 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 the neuronal synapses , in this case noradrenaline being the neurotransmitter in question. Reboxetine is the most relevant drug in this regard.

3.5. Dual Serotonin and Noradrenaline Reuptake Inhibitors

It acts in the same way as tricyclics, but with the difference that only affects the neurotransmitters on which it is intended to act . In other words, they are specific, thus eliminating a large part of the side effects. The example of a drug of this type currently available is venlafaxine.

4. Mood Stabilizers/Eutimizers

Another major mood disorder is bipolar disorder . In order to maintain a balanced and stable mood, two basic types of psychotropic drugs are also available:

4.1. Lithium salts

Although it is proposed that it produces an alteration of the G-protein that modulates the transmission of messages at the neuronal synapses, the mechanism of action of this type of psychopharmaceutical is not yet fully known. Despite the lack of exact knowledge as to why, this drug has demonstrated high efficacy in treating manic episodes and maintaining a stable mood .

However, it has the disadvantage that the difference between the amount needed to produce an euthymizing effect and that needed for poisoning is very narrow, and control by analysis of the level of lithium in the blood is essential. In addition, it can produce some side effects such as diarrhoea, acne, tremors, hair loss or cognitive loss, so there may be some resistance to treatment.

Anticonvulsants

Although these medications were developed to control seizures in cases of epilepsy, studies have shown that they are also highly effective in treating bipolarity .

Its functioning is based on favouring the action of GABA and reducing that of glutamate. Valproic acid, carbamazepine and topiramate are mainly used.

Bibliographic references:

  • Álamo, C.; López-Muñoz, F. and Cuenca, E. (1998): "Contribution of antidepressants and mood regulators to the knowledge of the neurobiological basis of affective disorders",PSYCHIATRY.COM – Vol. 2, No. 3
  • Azanza, J.R. (2006), Guía práctica de Farmacología del Sistema Nervioso Central. Creation and design.
  • Gómez, M. (2012). Psychobiology. Manual CEDE de Preparación PIR.12. CEDE: Madrid
  • Salazar, M.; Peralta, C.; Pastor, J. (2006). Manual of Psychopharmacology. Madrid, Editorial Médica Panamericana.
  • Stahl, S.M. (2002). Essential Psychopharmacology. Neuroscientific bases and clinical applications. Barcelona: Ariel.