see also anti-psychotic medications

• closely related to tricyclic antidepressants chemically.
• 2 main sub-groups:
  • aliphatic (eg. chlorpromazine (Largactil))
    • low clinical potency
    • medium extrapyramidal toxicity
    • high sedative actions
    • high hypotensive actions
  • piperazine (eg. fluphenazine)
    • high clinical potency
    • high extrapyramidal toxicity
    • low sedative action
    • very low hypotensive actions
• Their actions primarily appear to be related to central D2 antagonism but they also have antagonistic actions on the following receptors:
  • alpha1 adrenergic ⇒ hypotension
  • muscarinic ⇒ anticholinergic
  • 5HT2
  • D1 ⇒ extrapyramidal, dystonic reactions, neuroleptic malignant syndrome
  • H1 (some only have this action - those with shorter side chains)
  • quinidine-like (only thioridazine & mesoridazine) ⇒ prolonged QTc & risk of VT
  • actions on the chemo-receptor trigger zone (CTZ) ⇒ anti-emetic
  • lowered seizure threshold
• see also phenothiazine overdose
• see also neuroleptic malignant syndrome