Levomepromazine

Class	Antipsychotic
Chemistry	Phenothiazine
Routes of administration	Oral, IV, IM, s/c
Absorption	Well absorbed; bioavailability about 50-60%
Solubility	pKa 9.19, barely soluble in water
Distribution	VOD = 0.3-0.7L/kg, highly protein bound (90%)
Metabolism	Extensively metabolised by the liver (CYP3A4) into inactive metabolites
Elimination	Clearance is almost completely hepatic; only soome minimal amount is eliminated by the kidneys
Time course of action	Half life 15-30 hours, which corresponds to 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 due to the antimuscarinic activity are actually welcome in the palliative care setting - Antiemetic mechanism is likely due to a combination of all of the receptor effects at the chemoreceptor trigger zone
Clinical effects	#NAME?
Literature reference	Green et al, 2004
CICM details of understanding	Not specifically listed in the CICM syllabus
Mentioned around Deranged Physiology
Related SAQs