Active principle
Mirtazapine acts as a tetracyclic antidepressant centrally in the brain and very effectively inhibits certain receptors (so-called presynaptic ?2 receptors) there. Since these receptors are blocked, mirtazapine can also be called a ?2-receptor antagonist. In addition, receptors for serotonin, also known as 5-hydroxytryptamine (5-HT), are also blocked.
There are different groups of serotonin receptors. Mirtazapine blocks to be precise the 5-HT2A receptors and the 5-HT3 receptors. Blocking these receptors leads to an increased release of the neurotransmitters norepinephrine and serotonin from the nerve endings.
This is said to have a positive effect in depressive mood, as a lack of these messengers is believed to be responsible for depression (). Because of this mechanism of action, mirtazapine is also known as “NaSSA”. This abbreviation stands for “Noradrenergic and Specific Serotonergic Antidepressant“, which in German means something like noradrenergic and specifically serotonergic antidepressant.
In addition, a further group of receptors is blocked. These are histamine receptors (postsynaptic histamine H1-receptors). The sedative, i.e. calming effect of mirtazapine is attributed to this blockade. In summary, the antidepressant mirtazapine mainly blocks presynaptic ?2 receptors, serotonin receptors of the 5-HT2A and 5-HT3 types and postsynaptic histamine H1 receptors.
