Mirtazapine is an antagonist/inverse agonist at the following receptors:[65][66]
5-HT1A receptor (Ki = 18 nM; IC50 = 1,000 nM)[67]
5-HT2A receptor (Ki = 69 nM)
5-HT2B receptor (Ki = ? (~20-fold lower than for 5-HT2A/5-HT2C))[68]
5-HT2C receptor (Ki = 39 nM) (Inverse agonist) [69]
5-HT3 receptor (Ki = ? (similar to 5-HT2A/5-HT2C (mouse neuroblastoma cell)))[70]
5-HT7 receptor (Ki = 265 nM)
α1-adrenergic receptor (Ki = 608 nM (rat))
α2A-adrenergic receptor (Ki = 20 nM)
α2B-adrenergic receptor (Ki = ? nM (likely similar to α2A/α2B-adrenergic))[citation needed]
α2C-adrenergic receptor (Ki = 18 nM)
H1 receptor (Ki = 1.6 nM) [71]
mACh receptors (Ki = 794 nM (rat))
Dopamine D1 receptor (Ki = 4,167 nM)[72]
Dopamine D2 receptor (Ki = 1,460 nM)[73]
Dopamine D3 receptor (Ki = 5,723 nM)[74]
Dopamine D4 receptor (Ki = 25 nM)[73]
Mirtazapine has also shown affinity towards the norepinephrine transporter and perhaps also (results of test unspecified) the serotonin and dopamine transporter:
Norepinephrine transporter (IC50 = 260 nM)[73]
Serotonin transporter (IC50 = 100 nM)[75]
Dopamine transporter (IC50 = 1,000 nM)[76]