Comparison of affinities (Ki, nM)[45][46][47][48]
Receptor Quetiapine
(Cloned human receptors) Norquetiapine
(Cloned human receptors)
D1 994.5 99.8 (Rat receptor)
D2 379 196
D3 340 -
D4 2019 -
5-HT1A 394.2 45
5-HT2A 118 48
5-HT2C 1843 107
5-HT6 33 / 1864 -
5-HT7 307 76
α1A 22 144
α1B 14.6 46.4 (Rat receptor)
α2A 3630 237
α2C 28.85 -
H1 6.9 3.5
H2 41.24 -
M1 489 38.3 (Rat receptor)
M3 1631.5 -
NET >10000 12
(Source wikipedia)
the higher the number the Lower it effects that receptor. Seroquel gets metabolized to a second drug which is the second number
Dopamine has different receptors here. Seroquel and norseroquel only weakly binds to dopamine d1, d2 and d3 receptors. Therefore, low doses are likely to indirectly increase dooamine signaling very slightly by filling up autoreceptors on presynaptic neurons.
It is slightly stronger at seritonin receptors 5 ht2a and 5 ht2c these receptors down regulate even if they blocked. Therefore , seroquel and norseroquel bind to 5 ht2a and 5 ht2c receptors blocking them but paradoxically this still downregulates them these receptors are associated with depression and psychosis.
At 5 ht1a it is also pretty low potency so probably binds to autpreceptors increase seritonon ability to bind to post synaptic receptors at low doses which may further contibute to the increase speed of ssri onset paired with low dose seroquel.
alpha1a A2a and a2c probably adds to the hypotension and dizziness with booze esp at high doses and with net increasing noradrenaline signaling very sloghtly at low doses
Histamine antagonism might help reduce flushing