Prochlorperazine

Class	Dopamine receptor antagonist
Chemistry	Phenothiazine
Routes of administration	Oral, IV, IM, s/c
Absorption	Poor oral bioavailability, 12.5%
Solubility	pKa 8.39, only slightly soluble in water
Distribution	VOD=22L/kg, highly protein bound (up to 99%)
Metabolism	Extensively metabolised by the liver into inactive metabolites
Elimination	Clearance is almost completely hepatic; only soome minimal amount is eliminated by the kidneys
Time course of action	Half-life is 4-8 hours, which corresponds with the duration of effect
Target receptor	All phenothiazines are competitive antagonists of multiple receptors: - Muscarinic (Gq-coupled) - Serotonin (many, including 5-HT3) - Dopamine (D2, Gi-protein-coupled) - Histamine (Gq-protein-coupled) - Adrenergic (alpha)
Mechanism of action	Multiple mechanisms of action: - Sedation is mainly due to the antihistamine effects - Antipsychotic effect is due to D2 dopamine receptor effect This is also responsible for the tardive dyskinesia - Undesirable side effects are mainly due to the antimuscarinic and antiadrenergic activity - Antiemetic mechanism is likely due to a combination of all of the receptor effects at the chemoreceptor trigger zone
Clinical effects	#NAME?
Literature reference	Isah et al, 1991
CICM details of understanding	Level 3
Mentioned around Deranged Physiology	Classification of antiemetics
Related SAQs	Question 14 from the first paper of 2022 Question 23 from the first paper of 2016 Question 3 from the first paper of 2013 Question 17 from the second paper of 2012 Question 23 from the first paper of 2012 Question 10(p.2) from the first paper of 2010

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