The Indications and Uses of Psychotropic Drugs

Psychotropic drugs are chemicals used for the treatment of disorders of the mind. They affect the central nervous system by modifying behavior, perception, and consciousness.

The uses of psychotropic drugs are many and varied. They’re undoubtedly an important tool in psychology and psychiatry. They’ve helped substantially improve the prognosis of many mental illnesses. However, like all drugs, they can cause important side effects that must be assessed and controlled.

On the other hand, treatment with psychotropic drugs shouldn’t mean that we forget other ways of treating patients, including psychological therapy. Why? Because these resources complement each other in order to help resolve the underlying causes of many of these problems. We’ll be looking at the uses of psychotropic drugs in this article.

What are psychotropic drugs?

Psychotropic drugs are drugs used to treat psychological disorders. They’re chemical substances that act on the nervous system, modifying psychological activity and mental and emotional processes.

In the early 1950s, the discovery of chlorpromazine revolutionized psychopharmacology. From that moment on, advances in this field have continued at a dizzying pace.

Even today, it continues to be an important field of research in the search for more specific drugs with fewer side effects.

How do psychotropic drugs work?

Although the causes of many mental illnesses are still unknown, it’s been proven that they’re related to metabolic alterations, specifically in brain neurotransmitters (NTs).

These chemical substances, released in the neuronal synapse and that act on specific receptors, intervene in the transmission of nerve impulses. The modification of the effects of NTs is the mechanism of action behind most psychotropic drugs.

The main NTs these drugs act on are:

• Acetylcholine.
• Noradrenaline.
• Dopamine.
• Serotonin (5-hydroxytryptamine).
• GABA (gamma-aminobutyric acid).

Scientists generally consider that, in states of cerebral hyperactivity, the release of NTs increases in the synapse. However, in the most depressive states, there’s a decrease in the release and/or density of the NTs in the intersynaptic space.

According to this, some psychoactive drugs aimed at treating psychotic and agitated states act by decreasing the concentration of certain NTs or by blocking their receptors. On the other hand, others, which are used to treat depression, act by increasing their concentration.

But this isn’t the only explanation. The nervous system is very complex and is influenced by many factors. Because of this, it’s difficult to know all the mechanisms involved in it. Therefore, as Silvia Wikinski states, we can’t explain many aspects of mental illnesses simply by using these processes.

Types of psychotropic drugs

Although there are many classifications, we can group them under four major headings:

• Neuroleptics or antipsychotics.
• Anxiolytics and sedative-hypnotics.
• Antidepressants.
• Eutimizers or mood stabilizers.

To these, we can add psychostimulants, anti-dementia drugs, or psychopharmaceuticals, among others, for the treatment of dependencies. However, we’re going to focus on these four main groups.

Types and uses of psychotropic drugs

1. Neuroleptics or antipsychotics

The main indication for antipsychotics is the treatment of psychoses such as schizophrenia. This is a complex illness characterized primarily by:

• Positive (outward) symptoms – delusions and hallucinations.
• Negative (inward) symptoms – apathy and social isolation.

We can classify antipsychotic drugs as follows:

Typical antipsychotics

• Main mechanism of action. Blocking dopamine D2 receptors of the mesolimbic pathway.
• Main effect. Cessation of positive symptoms (but little effect on negative symptoms).
• Important side effects. Extrapyramidal symptoms and hyperprolactinemia due to the blockage of other dopaminergic pathways.
• Examples. Chlorpromazine and haloperidol.

Atypical antipsychotics

• Main mechanism of action. Blocking dopamine D2 receptors and serotonin 5-HT2A receptors.
• Main effect. Cessation of positive and negative symptoms, because, by blocking the serotonin, the side effects of dopamine blockage are avoided.
• Side effects. Hypotension, tachycardia, dizziness, and sedation.
• Examples. Risperidone, quetiapine, olanzapine, clozapine, and ziprasidone

2. Anxiolytics and hypnotic sedative agents

Anxiolytics, which focus on the treatment of anxiety, are the most-used psychotropic drugs today, as stated by the OCU. On the other hand, many of them are also used as sedative agents for the treatment of insomnia.

Their main mechanism of action is to promote the actions of GABA agonists in the GABA-A receptors. Thus, it increases the inhibitory effect of this neurotransmitter. GABA is responsible for regulating neuronal excitation in the nervous system.

We can highlight several groups of drugs:

Barbiturates

• Main effect. Sedative
• Used for the treatment of anxiety before benzodiazepines were created.
• They cause a lot of dependence and, in the long term, neurological damage,

Benzodiazepines

• Main effect. Anxiolytic, hypnotic-sedative, muscle relaxant, and also anticonvulsant.
• Causes fewer side effects, less addictive, and less sedative than barbiturates. For this reason, benzodiazepines are the most widely-used anxiolytics.
• Some benzodiazepines take longer to act but last longer (diazepam and clonazepam). Others have faster action, but the effects aren’t as lasting (lorazepam and alprazolam)

Short-acting hypnotic sedative agents

• Main effect. They act as GABA agonists, but only on receptors linked to sleep and hypnotic effects.
• Less anxiolytic, anticonvulsant, and myorelaxant effects than benzodiazepines.
• For example, Zolpidem.

Buspirone

• Main effect. An anxiolytic with hardly any hypnotic or tranquilizing effects. It acts only on serotonin, not on GABA.
• It’s less effective than benzodiazepines and its effects take longer to appear.
• Useful in generalized anxiety disorder.

3. Antidepressants

Antidepressant drugs, after anxiolytics, are the most widely-prescribed psychotropic drugs today. They’re prescribed for the treatment of depression, generally characterized by a decrease of NTs in the neuronal synapses. Therefore, in general terms, antidepressant drugs increase the concentration of these substances through different mechanisms of action.

There are many types of antidepressants. Below, we’ll highlight three important groups.

MAOIs

• Mechanism of action. Inhibition of the monoamine oxidase enzyme. This enzyme is responsible for the elimination of excess NTs such as serotonin, dopamine, or noradrenaline.
• They can be irreversible and non-selective inhibitors, or reversible and selective.
• Important side effects. High risk of hypertension and weight gain.
• Not usually the drugs of choice.
• An example is isocarboxazid.

Tricyclic antidepressants

• Mechanism of action. Inhibition of serotonin and noradrenaline reuptake. They also affect other NTs.
• Side effects. Antihistamine and anticholinergic effects. For example, dry mouth, blurred vision, and constipation.
• They were widely used for depression until the advent of SSRIs.
• For example, imipramine and amitriptyline.

SSRI

• Mechanism of action. Selective serotonin reuptake inhibition. They don’t affect other NTs.
• They’re the safest antidepressants with the fewest side effects. They’re usually the first treatment choice.
• Some examples are sertraline, fluoxetine, and citalopram.

4. Eutimizers or mood stabilizers

These are drugs used in the treatment of mood disorders, such as bipolar disorder, characterized by manic and depressive episodes.

There are two groups of mood-stabilizing drugs:

Lithium salts

• The oldest and best-known mood-stabilizing drug.
• Different mechanisms of action.
• Very narrow therapeutic margin. Therefore, it’s necessary to control its levels in the blood.

Anticonvulsants

• Mechanism of action. They enhance the inhibitory action of GABA and reduce the excitatory action of glutamic acid.
• For example, valproic, carbamazepine, and topiramate.

In short, although the causes of many mental illnesses are still unknown, psychotropic drugs can substantially improve patients’ prognosis and bring us closer to a cure for these disorders.

Nowadays, pharmacology is highly developed. There are many different psychotropic drugs, and it’s possible to personalize therapies by individually adapting them to each patient.