Tricyclic antidepressants: uses and side effects.

A review of the functioning and the positive and negative effects of this type of psychotropic drug.

Although less used today than SSRIs and other more modern antidepressants, tricyclics were for many decades the pharmacological treatment of choice for depressive disorders.

In this article we will describe what tricyclic antidepressants areWhat are tricyclic antidepressants, what are they used for and what are their most common side effects.

What are tricyclic antidepressants?

Tricyclics are psychotropic drugs used to treat depressive disorders.s, although in many countries they have been replaced as drugs of choice by other more effective antidepressants. The effects of drugs useful for treating depression are usually related to serotonin and norepinephrine agonism.

The name of these drugs comes from their chemical structure: they are composed of three rings of atoms. Years after the appearance of tricyclic antidepressants, tetracyclic antidepressants also appeared, which are made up of four rings instead of three.

Since the appearance of imipramine, the first imipramine, the first Antidepressant of this class, appeared, a large number of tetracyclic antidepressants have been manufactured.Since the appearance of imipramine, the first antidepressant of this class, a large number of tricyclics have been manufactured with some differential characteristics. Among the most common are clomipramine, amitriptyline, nortriptyline, desipramine, maprotiline, doxepin, amoxapine, protriptyline and trimipramine.

What is their mechanism of action?

Tricyclic antidepressants are monoamine agonists, a type of neurotransmitter that is highly relevant in the human nervous system. These potentiating effects affect serotonin, noradrenaline and, less significantly, dopamine. and, less significantly, dopamine.

Its main therapeutic activity is due to the inhibition of the reuptake of these neurotransmitters, which increases the availability of monoamines in the synaptic space. However, they also collaterally affect histamine and acetylcholine, on which they exert a collateral effect.on which they exert an antagonistic effect.

Due to the low specificity of their mechanism of action, which does not target only the most relevant neurotransmitters as is the case with other antidepressants, tricyclics can be useful in alleviating symptoms of depression but also cause very significant side effects and adverse reactions.

History of these drugs

Tricyclics were discovered in the process of manufacturing antipsychotic drugs. In 1950, clomipramine, a neuroleptic with a tricyclic structure, was synthesized.. Information on this drug led shortly thereafter to the creation of imipramine, the first tricyclic used specifically to treat depression.

In recent decades the popularity of tricyclics has declined in most parts of the world because of the discovery of more effective and safer antidepressant drugs, particularly selective serotonin reuptake inhibitors (SSRIs) and fourth-generation antidepressants such as venlafaxine and reboxetine.

Their functions

Despite their name, tricyclic antidepressants are not only used in cases of depression, but throughout their history they have been applied to a large number of different psychological disorders.

1. Depressive disorders

The main indication for tricyclics is the treatment of depressive disordersThe main indication for tricyclics is the treatment of depressive disorders, both major depression and milder variants, in particular dysthymia. They are currently prescribed mainly in melancholic depression and in cases that do not improve by taking other antidepressants with fewer side effects.

Anxiety disorders 2.

Some tricyclics are occasionally used to treat different anxiety disorders: imipramine has been shown to be effective in generalized anxiety disorder and panic disorder, while while clomipramine continues to be used in cases of obsessive-compulsive disorder (closely related to depression) and (closely related to depression) and amitriptyline in post-traumatic stress disorder.

3. Chronic pain

Chronic pain-related disorders that have been treated with tricyclics include fibromyalgia and neuropathic pain; serotonin and noradrenaline agonism are thought to indirectly influence endogenous opioid production. indirectly influences the production of endogenous opioids, which have analgesic effects.which have analgesic effects. Amitriptyline appears to be particularly useful in this regard.

4. Insomnia

The sedative side effects of tricyclic antidepressants have led to their occasional use to treat symptoms of insomnia. However, it is important to keep in mind that there are other more specific drugs for these problems, and above all that psychological therapy is the most advisable way to deal with sleeping difficulties.

5. Eating disorders

Again, the therapeutic effects of tricyclics in eating disorders are associated with one of their therapeutic effects. are associated with one of their most frequent side effectsweight gain. In particular, clomipramine is sometimes prescribed as part of therapy for anorexia nervosa.

6. Nocturnal enuresis and night terrors

Imipramine is effective in treating two childhood sleep disorders: nocturnal enuresis and night terrors. These effects are related to the decrease in delta or slow-wave sleep, during which these episodes occur.during which these episodes appear.

Side effects of tricyclic antidepressants.

Although the side effects associated with the use of tricyclic antidepressants depend largely on their agonism or antagonism to certain neurotransmitters, in this section we will focus on the side effects most commonly associated with this class of psychotropic drugs as a whole.

As mentioned in the previous section, among the most common side effects of tricyclic antidepressants are sedation and weight gain, both due to the inhibition of histamine activity. are sedation and weight gain; both are due to the inhibition of histamine activity.

The blockade of acetylcholine receptors causes side effects such as constipation, urinary retention, dry mouth, blurred vision and memory problems.. On the other hand, inhibition of alpha-adrenergic receptors is related to blood circulation disturbances, especially dizziness and orthostatic hypotension.

Among the serious adverse reactions to the consumption of tricyclics, the following stand out neuroleptic malignant syndrome, consisting of the appearance of alterations in blood circulation, especially dizziness and orthostatic hypotension.consisting of the appearance of respiratory, cardiac and muscular alterations that can lead to coma and, in approximately one-fifth of cases, death. This syndrome seems to be more frequent in people over 50 years of age.

The high addictive potential of tricyclics should also be noted, because pharmacological tolerance develops easily. The appearance of an intense withdrawal syndrome after abrupt discontinuation of consumption is also a consequence of tolerance. In addition, the risk of overdose and the risk of overdose and suicide is also strikingly high..