Serotonin syndrome: causes, symptoms and treatment

Serotonin (5-HT) is a neurotransmitter produced by the body, and it is necessary for the proper functioning of the body for several reasons because it is responsible for the regulation of certain physiological processes. But an excess of serotonin causes Serotonin syndrome, A set of symptoms of varying severity that affect people using antidepressants.

Its most common cause is overdose or the interaction between drugs capable of increasing the release of serotonin.

In this article, we explain in detail which functions are responsible for the regulation of serotonin:

  • “Serotonin: the 6 effects of this hormone on your body and mind”

The importance of serotonin for the body

Serotonin is a chemical that neurons communicate with, i.e. neurotransmitter. It is synthesized from tryptophan, an essential amino acid supplied by the diet because it is not made by the body. Some foods that contain tryptophan are: oats, wheat, almonds, eggs, or blue fish.

But although many believe that serotonin is only found in the brain (acting as a neurotransmitter), the central nervous system (CNS) contains only 5% 5-HT, so the small intestine produces the rest, And this serotonin never reaches the brain, but has other functions in the body (eg it regulates the state of smooth muscle contraction of blood vessels).

Although serotonergic neurons are present in smaller amounts in the brain, their functions in the CNS are very varied, as these neurons are highly branched and make a large number of synapses. Some of the most important functions of serotonin are: regulation of appetite, regulation of positive and negative moods, intervention in the sensation filter (with regard to concentration), control of body temperature level , etc.

Serotonin syndrome can be fatal

Excessive stimulation of serotonin on postsynaptic 5-HT1A and 5-HT2A receptors at the central and peripheral level a negative effects for the organization which they can become very serious and even fatal. The set of symptoms attributed to excessive serotonin neurotransmission activity on these receptors is known as serotonin syndrome and was originally described by Oates in 1960.

The use of antidepressants has become very popular in recent years, and this is the main cause of the increase in cases of this syndrome. Antidepressants that inhibit serotonin reuptake are the treatment of choice for depression, anxiety disorders, generalized anxiety disorder, obsessive-compulsive disorder, post-traumatic stress disorder, premenstrual diaphoretic and bulimia nervosa.

Overdose or a combination of these drugs can cause an individual to suffer from Serotonin Syndrome, and since there are many drugs that can cause this condition, the most well-known pharmacological substances associated with Serotonin Syndrome are as follows:

Psychiatric drugs

  • heterocyclic antidepressants: Amitriptyline, imipramine, monoamine oxidase inhibitors (MAOIs)
  • Selective serotonin reuptake inhibitor: citalopram, escitalopram, fluoxetine (prozac), paroxetine, sertraline
  • Selective dopamine and / or norepinephrine reuptake inhibitors: bupropion, duloxetine, venlafaxine
  • Humor stabilizers: Carbamazepine, liti

Neurological drugs

  • Parkinson’s disease agents: levodopa, amantadine, bromocriptine
  • opioid agonists: meperidine, fentanyl, hydrocodone, pentazocine
  • amphetamines: methylphenidate, amphetamines
  • Headache medications: sumatriptan, eletriptan, rizatriptan
  • Antiemetics: ondansetron, granisetron, metoclopramide
  • Cough suppressants: dextromethorphan

other drugs

  • antibiotics: linezolid
  • Drugs of abuse: cocaine, ecstasy, LSD

  • natural substances: Hypericum, caffeine, l-tryptophan, ginseng
  • other anesthetics: tramadol

Symptoms of serotonin syndrome

Symptoms of serotonin syndrome begin within hours of an overdose or an interaction between drugs that increase the presence of serotonin and are characterized by the so-called triad: autonomic, neuromuscular and neurological dysfunction. If it is not diagnosed in time and appropriate action is taken, serotonergic toxicity is associated with high mortality.

The characteristic symptoms are varied and can be mild or severe. These are the symptoms of a person with serotonin syndrome:

Treatment of serotonin syndrome

To properly treat serotonin syndrome, it is necessary to have one. updated pharmacological history, Which includes over-the-counter drugs or substances and plant protection products.

Mild to moderate signs of serotonergic toxicity may go away within 24 hours of stopping drug treatment, but this depends very much on the half-life of the substances involved. Severe cases require immediate hospitalization and intensive care, as the patient may experience severe hyperthermia, rhabdomyolysis, or respiratory failure.

For treatment, even in mild cases, administration of benzodiazepines is common to decrease restlessness, convulsive movements and muscle stiffness. Proper hydration, control of autonomic instability, or control of fever are common as a supportive measure.

Cyproheptadine (Periactin), an H1 antagonist drug with activity on 5-HT2A in smooth muscle and with anticholinergic and antiserotonergic properties is beneficial because it manages to reverse antidepressant effects, and a single dose can block around 85 to 95 % of serotonin receptors.

Bibliographical references:

  • González AR (2009). Serotonin syndrome. University of Costa Rica Medical Journal, 3 (3): 16-30
  • Gillman P. Ken. (2006). A review of serotonin toxicity data: implications for the mechanisms of action of antidepressant drugs. Psychiatry Biol; 59: 1046-1051.

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