Help replacing meto with quetiapine

[geepeedee]

how much quetiapine should i use as a replacement for meto in my SN protocol?

 

[absolutethistime]

I would be very careful trying to replace it with Quetiapine.

Metoclopramide
Core action:

• Strong D2 receptor antagonist (especially in the chemoreceptor trigger zone)
• Mild 5-HT3 antagonist
• 5-HT4 agonist (prokinetic → gut motility)

Dose vs binding (simplified reality)

• Low dose (~5–10 mg):
  • Already substantial D2 blockade (this drug doesn't "ease into it")
  • Enough for anti-nausea effects
• Moderate dose (~10–20 mg):
  • Near-maximal central D2 occupancy
  • Increased risk of extrapyramidal symptoms (EPS)
• High dose / repeated dosing:
  • Doesn't meaningfully increase D2 selectivity—just increases side effects
  • Acute dystonia, akathisia, parkinsonism risk climbs fast

Quetiapine
Core action (very dose-dependent):

• H1 (histamine) blockade → sedation
• 5-HT2A antagonism
• D2 antagonism (weak + transient)
• α1 blockade → orthostasis

Dose-dependent binding profile

• Very low dose (25–50 mg):
  • Dominant: H1 blockade
  • Result: heavy sedation, basically an antihistamine in disguise
  • Minimal D2 occupancy
• Low–moderate (100–300 mg):
  • Strong 5-HT2A antagonism
  • Some D2 engagement, but still relatively weak
  • Used for mood stabilization / bipolar depression
• High dose (300–800 mg):
  • Meaningful D2 occupancy (~40–60%), but still lower than typical antipsychotics
  • Antipsychotic effects emerge
  • Still less EPS than drugs with tighter D2 binding

 

[geepeedee]

thanks, that's very helpful.