Mirtazapine: effects and uses of this antidepressant drug

Major depression is one of the best known and most common mental problems in the world. The high level of suffering and anguish that this disorder generates and its high prevalence has meant that throughout history there have been numerous ways of treating it.

At present we have a wide range of possibilities, one of the most common strategies being the combined use of psychotherapy and psychopharmacology. Regarding the latter, it has generated various substances to combat depressive symptoms, one of them being mirtazapine.

• Related article: "Types of antidepressants: characteristics and effects"

Mirtazapine: what is this drug like?

Mirtazapine is a substance with psychoactive properties useful in combating depressive symptoms, being part of the group of antidepressants.

It is a relatively recent drug, a piperazan-azepine analog of mianserin, which has a tetracyclic structure and acts as a norepinephrine and serotonin agonist, increasing its levels at the brain level. Thus, within the antidepressants it is classified as Noradrenergic and Specific Serotoninergic Antidepressant or NaSSa.

Mirtazapine is a drug whose effectiveness is high and of a level similar to that of other antidepressants such as SSRI, apparently acting with a similar or slightly greater speed than these and having relatively few side effects (being less likely to appear sexual and / or gastrointestinal symptoms). In fact, in the treatment of depression, some studies seem to indicate that mirtazapine has a greater effect than SSRIs after a treatment of six to twelve weeks

This medicine is usually given on its own, although in some cases of severe depression it can be combined with other drugs such as venlafaxine in what is known as California Rocket Fuel to enhance the effects antidepressants, demonstrating greater effectiveness than some MAOIs and a better response and referral rate.

• You may be interested: "Types of psychotropic drugs: uses and side effects"

Mechanism of action

The main mechanism of action of mirtazapine is due to its action on the receptors of noradrenaline Y serotonin of the nervous system, acting as an agonist for these hormones.

This action is not due to the inhibition of the reuptake of the aforementioned neurotransmitters, but is carried out by antagonism of the postsynaptic serotonin 5-HT2 and 5-HT3 receptors together with that of the receptors presynaptic alpha 2. This causes the release of serotonin and norepinephrine to be increased, although it does not greatly alter their reuptake.

In addition to this, it must be taken into account that has an antihistamine effect, which can generate undesirable side effects by blocking and antagonizing histamine. To a much lesser degree but nevertheless to be taken into account, it has been found that the Mirtazapine also has mild anticholinergic effects, affecting the synthesis and transmission of acetylcholine.

Applications of this antidepressant

Mirtazapine its main approved indication is major depression, in which it is effective and appears to act faster than compared to other antidepressants such as SSRIs.

However, although it is not indicated for other disorders, different trials have been carried out in other mental conditions and even medical problems in which mirtazapine appears to have a certain level of effectiveness. For example, It has been shown to be effective in treating anxiety disorders. Also in post-traumatic stress disorder and obsessive-compulsive disorder.

At a more physiological level, although sedation and weight gain are apparently undesirable secondary symptoms, they can sometimes be an advantage in some patients. This is what happens for example with patients in advanced ages or with anxiety problems, with weight loss or insomnia. It would also be applicable in patients with anorexia nervosa. Its antihistamine action could act to relieve symptoms of itching and headaches.

• You may be interested: "Major depression: symptoms, causes and treatment"

Side effects and contraindications

Mirtazapine is a very useful medicine in the treatment of depression and other problems, but its action at the brain level can generate undesirable side effects for those who consume.

Among these side effects, sedation and weight gain stand out as the most common that can generate their antihistamine effects. It is also common for dizziness and nausea to occur, and also other problems such as constipation or dryness. It is also not strange that it generates a decrease in blood pressure. Less frequent are edema facial, vertigo and increased cholesterol and triglycerides, as well as polyuria, agitation or anxiety. It can also generate hyper or hypokinesia. Finally, although highly unlikely, there is a risk of agranulocytosis, dehydration, seizures, sexual problems, hallucinations, manic episodes, and depersonalization.

The main contraindications of this psychotropic drug are found in those cases in which the potential users suffer from heart problems (especially if they have recently had a heart attack), liver or kidney It should also not be used by patients with epilepsy, glaucoma or diabetes mellitus.. Patients with urinary problems or with mental disorders such as bipolar disorder or psychotic disorders are also contraindicated. It is also not recommended for use during pregnancy or lactation.

Also, although it is sometimes used in combination with venlafaxine, its consumption together with other psychotropic drugs, their combination with antidepressants being especially dangerous MAOIs that can lead to serotonin syndrome which can lead to cardiorespiratory arrest, hyperthermia, seizures, coma, or even death. Nor should it be combined with alcohol or other drugs.

• Related article: "Serotonin syndrome: causes, symptoms and treatment"

Bibliographic references

• From Lucas, M.T. & Montañés, F. (2006). Use of mirtazapine in panic disorder. Psychiatrist. Biol., 13; 204-210.
• Holm, K.J. & Markham, A. (1999). Mirtazapine. Review of its use in major depression. Drugs, 57 (4): 607-631.
• Watanabe, N.; Omori, I.M.; Nakagawa, A.; Cipriani, A.; Barbui, C.; Churchill, R. & Furukawa, T.A. (2011). Mirtazapine versus other antidepressant agents for depression. Cochrane Database of Systematic Reviews, 12.