Serotonin syndrome: causes, symptoms and treatment

The serotonin (5-HT) is a neurotransmitter produced by the body, and it is necessary for the proper functioning of the body for various reasons since it is in charge of regulating certain physiological processes. But excess serotonin causes Serotonin syndrome, a set of symptoms of varying severity that affects individuals who use antidepressants.

Its most common cause is overdose or the interaction between drugs that have the ability to increase the release of serotonin.

In this article we fully explain what functions serotonin is responsible for regulating:

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

The importance of Serotonin for the body

Serotonin is a chemical substance with which neurons communicate, that is, a neurotransmitter. This is synthesized from tryptophan, an essential amino acid provided through the diet because it is not manufactured by the body. Some foods that contain tryptophan are: oats, wheat, almonds, eggs or blue fish.

But although many think that serotonin is only found in the

brain (acting as a neurotransmitter), the Central Nervous System (CNS) only contains 5% of 5-HT, since the small intestine produces the rest, and this serotonin never reaches the brain, but has other functions in the body (for example, it regulates the state of contraction of the smooth muscles of the blood vessels).

Although serotonergic neurons are present in less quantity in the brain, their functions in the CNS are very varied, since these neurons are highly branched and carry out a large amount of synapse. Some of the most relevant functions of serotonin are: regulate appetite, regulate positive and negative moods, intervene in the sensation filter (so it is related to concentration), control the body temperature level, etc.

Serotonin syndrome can be fatal

Excessive stimulation of serotonin on the postsynaptic 5-HT1A and 5-HT2A receptors at the central and peripheral level has Negative effects for the organism that can be very serious and even fatal. The set of symptoms attributed to an excessive activity of serotonergic neurotransmission on these receptors is known as serotonin syndrome, and was originally described by Oates in 1960.

In recent years, the use of antidepressants has become very fashionable, 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, panic disorders, generalized anxiety, obsessive compulsive disorder, posttraumatic stress, premenstrual diaphoretic and bulimia nervosa.

Overdose or the combination of these drugs can lead an individual to suffer from Serotonin Syndrome, and since there are many medications that can cause this condition, below are the best-known pharmacological substances that are associated with the Syndrome serotonergic:

Psychiatric Medications

• Heterocyclic antidepressants: amitriptyline, imipramine, monoamine oxidase inhibitors (MAOIs)
• Selective serotonin reuptake inhibitors: citalopram, escitalopram, fluoxetine (prozac), paroxetine, sertraline
• Selective dopamine and / or norepinephrine reuptake inhibitors: bupropion, duloxetine, venlafaxine
• Mood stabilizers: carbamazepine, lithium

Neurological Medications

• Parkinsonian agents: levodopa, amantadine, bromocriptine
• Opioid agonists: meperidine, fentanyl, hydrocodone, pentazocin
• Amphetamines: methylphenidate, amphetamines
• Headache medications: sumatriptan, eletriptan, rizatriptan
• Antiemetics: ondansetron, granisetron, metoclopramide
• Cough suppressants: dextromethorphan

Other medications

• Antibiotics: linezolid
• Drugs of abuse: cocaine, ecstasy, LSD
• Natural substances: St. John's wort, caffeine, l-tryptophan, ginseng
• Other anesthetics: tramadol

Symptoms of Serotonin Syndrome

Symptoms of Serotonin Syndrome begin within hours of an overdose or interaction between drugs that increase the presence of serotonin, and are characterized by what is known as a triad: autonomic, neuromuscular and neurological. If it is not diagnosed in time and appropriate measures are taken, serotonergic toxicity is associated with high mortality.

Characteristic symptoms are varied and can be mild or severe. Below is the symptomatology presented by an individual with Serotonin Syndrome:

Treatment of serotonin syndrome

To treat Serotonin Syndrome properly it is necessary to have a updated drug history, which includes over-the-counter drugs or substances and phytopharmaceuticals.

Mild and moderate symptoms of serotonergic toxicity can resolve within 24 hours after injection. suspension of drug treatment, but much depends on the half-life of the substances involved. Severe cases require immediate hospitalization and intensive care, as the patient may suffer severe hyperthermia, rhabdomyolysis or respiratory failure.

For treatment, even in mild cases, the administration of benzodiazepines is common to reduce agitation, pseudo-convulsive movements and muscle stiffness. Correct hydration, control of autonomic instability or control of fever is 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 It is beneficial, since it manages to reverse the antidepressant effects, and a single dose can block approximately 85 to 95% of the receptors serotonergic.

Bibliographic references:

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