What is the classification of Remeron (mirtazapine)?

Classification of Mirtazapine (Remeron)

Mirtazapine (Remeron) is classified as a noradrenergic and specific serotonergic antidepressant (NaSSA).

Pharmacological Classification Details

Mirtazapine has a unique mechanism of action that distinguishes it from other antidepressant classes:

• It functions as a tetracyclic antidepressant with noradrenergic and specific serotonergic activity 1
• It acts as an antagonist of:
  • Presynaptic alpha2-adrenergic autoreceptors and heteroreceptors
  • Postsynaptic 5-HT2 (serotonin type 2) receptors
  • Postsynaptic 5-HT3 (serotonin type 3) receptors 2

Pharmacodynamic Properties

The unique receptor profile of mirtazapine results in:

• Increased noradrenergic neurotransmission
• Enhanced serotonergic activity, particularly at 5-HT1A receptors 2
• Sedating effects, particularly at lower doses, due to H1-histamine receptor antagonism
• Minimal anticholinergic effects compared to tricyclic antidepressants
• Absence of serotonin reuptake inhibition (unlike SSRIs) 2

Clinical Applications

Mirtazapine is primarily indicated for:

• Major depressive disorder 3
• Off-label use for insomnia (particularly at lower doses) 1

Preliminary evidence suggests potential efficacy in:

• Anxiety disorders
• Post-traumatic stress disorder
• Panic disorder
• Social anxiety disorder
• Obsessive-compulsive disorder 3

Dosing Considerations

• Typical starting dose: 15 mg once daily at bedtime
• Effective dosage range: 15-45 mg daily
• Maximum therapeutic dose: 45 mg daily 4
• Lower doses (7.5-15 mg) are often more sedating than higher doses
• Elderly patients typically start at lower doses (7.5-15 mg) 4

Distinguishing Features from Other Antidepressant Classes

Unlike other antidepressant classes, mirtazapine:

• Does not inhibit the reuptake of serotonin or norepinephrine (distinguishing it from SSRIs, SNRIs, and TCAs)
• Has minimal sexual dysfunction side effects compared to SSRIs
• Has minimal gastrointestinal side effects compared to SSRIs
• May have a faster onset of action than SSRIs 5
• Is associated with increased appetite and weight gain (unlike most SSRIs) 6

Common Side Effects

• Sedation (more common at lower doses)
• Increased appetite
• Weight gain
• Dry mouth
• Dizziness 7

In summary, mirtazapine represents a distinct class of antidepressant (NaSSA) with a unique receptor profile that differentiates it from traditional antidepressants like SSRIs, SNRIs, and tricyclic antidepressants.