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SSRI: types, functioning and effects of this antidepressant

SSRI: types, functioning and effects of this antidepressant

April 30, 2024

Of all the psychopharmaceuticals, the serotonin reuptake inhibitors (SSRIs) are the most prescribed both in Spain and in most industrialized countries. This type of antidepressant is popular for several reasons: it is indicated for more prevalent disorders such as major depression or anxiety disorders, are effective and their side effects are almost always well tolerated.

If we understand why depression occurs, we can also understand how SSRIs are effective in treatment and through what mechanism they act . We will briefly review its operation, what its properties and adverse effects are and in what disorders it is more frequent to be prescribed.

  • Related article: "Psychotropic drugs: drugs that act on the brain"

What is an SSRI?

Although it can be cumbersome, it is necessary to understand how neurons work at the cellular level when they communicate with each other through neurotransmitters in order to understand how inhibitors of serotonin reuptake modify neuronal activity.

  • Maybe you're interested: "Types of neurons: characteristics and functions"

Release and reuptake of serotonin

When the neurons communicate with each other, the presynaptic neuron (the emitter of chemicals that the other will receive) releases neurotransmitters into the synaptic space, which they are picked up by the receptors of the postsynaptic neuron . In the case of neurotransmitter circuits called serotonin, neurons use this neurotransmitter to communicate. One neuron releases serotonin into space and the other picks it up, understanding that it must be activated.

What happens is that not all neurotransmitters are received and sometimes floating in the intersynaptic space. There are some pumps that are responsible for cleaning this excess neurotransmitter and returning it to the presynaptic neuron.

In depression and other disorders it is hypothesized that there is very little serotonin in this space, so that postsynaptic neurons, hungry for serotonin, create many receptors to receive neurotransmitters but do not activate and do not release anything, as in a state of hibernation .

The SSRIs block the recapture bombs and allow more and more serotonin to accumulate in space. The postsynaptic neurons, as they perceive that the concentration of serotonin in space is greater and there is more neurotransmitter available, begin to decrease the number of recipients because they no longer believe they need so many. The neuron relaxes its strict norm of not releasing anything, and begins to let go of serotonin and to activate the rest of neurons of the circuit.

Types of SSRIs

Not all SSRIs are the same. Each drug uses a different active ingredient that will have a specific therapeutic dose. Also, as each active ingredient acts on different serotonin receptors , its side effects will also be different. It is this relationship between efficacy, safety and tolerance of the drug that defines whether it is preferable to use one or the other.

Below you can see a list of the SSRIs marketed. In pharmacies we will find them under different trade names depending on the country. For example, Fluoxetine is more widely known as Prozac , or escitalopram under the name of Cipralex:

  • Citalopram
  • Escitalopram
  • Fluoxetine
  • Fluvoxamine
  • Paroxetine
  • Sertraline

Safety, tolerance and side effects

In general, SSRI psychoactive drugs are safe . Contrary to what happens with lithium salts, the toxic dose is difficult to reach by mistake when we take SSRIs. Also, do not produce the same tolerance as other drugs such as benzodiazepines, so it is not necessary to increase the dose by the properties of SSRI.

On the other hand, the side effects that it produces are minor . They can produce nausea, dry mouth, sweating, anorgasmia, decreased sexual desire and blurred vision, among others much less frequent. Abrupt cessation of SSRI use, even if it does not generate addiction, can cause withdrawal symptoms, as the brain becomes accustomed to the presence of the substance. For this reason, the withdrawal of the drug is gradual.

The SSRIs interact with many other medications , so that close supervision by the psychiatrist who prescribes them is necessary. For example, there are some antidepressants that remain in the system for days or weeks after cessation of administration. When someone taking this type of antidepressant changes to SSRIs, the effects of the previous medication that has not yet been excreted and that of the SSRIs may overlap.This causes the patient to suffer a serotonin syndrome, an excess of serotonin that causes a confusional state, agitation, headache, nausea, etc. and must be treated urgently.

Uses in psychiatry

In the same way as tricyclic antidepressants, SSRIs are used for a wide variety of disorders. Naturally, the main use is in patients with major depressive episodes or depressive symptoms. The use of SSRIs It is very effective to end depressive symptomatology that can be found in patients with anxiety disorders, personality disorders, gender dysphoria, bulimia nervosa, autism, etcetera.

Since serotonin is also implicated in anxiety, the benefit of SSRIs in anxiety disorders is often double. On the one hand it appeases the negative state of mind, and on the other it reduces the experience of anxiety . Especially in patients who experience chronic levels of anxiety as in generalized anxiety disorder, in obsessive-compulsive disorder, post-traumatic stress or acute stress reactions will be very useful serotonin reuptake inhibitors.

These patients, when taking SSRIs, experience a significant decrease in anxiety levels. This allows them to relax the worries and anxiety that torments them, recovering a large part of their quality of life and leading a functional life.

Pharmacology - ANTIDEPRESSANTS - SSRIs, SNRIs, TCAs, MAOIs, Lithium ( MADE EASY) (April 2024).

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