Pharmacology for Anaesthesia and Intensive Care

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18 Antiemetics and related drugs

Table 18.2.Effects of some dopamine antagonists.

Chlorpromazine Thioridazine Prochlorperazine

Sedation +++ ++ +

Anticholinergic

effects

++ +++ +

Extrapyramidal

effects

++ + +++

Prochlorperazine

Uses

Prochlorperazine is effective in the prevention and treatment of PONV and vertigo,

as well as in schizophrenia and other psychoses.

Effects


Central nervous system – extrapyramidal effects are seen more commonly in

this class of phenothiazine. Acute dystonias and akathisia seem to be the most

commonly encountered effects. Children and young adults are the most affected

groups. When used peri-operatively it produces only mild sedation and may pro-

long the recovery time but the effects are not marked.


Group specific – in common with other phenothiazines prochlorperazine may

cause cholestatic jaundice, haematological abnormalities, skin sensitization,

hyperprolactinaemia and rarely the neuroleptic malignant syndrome.

Kinetics

Absorption by the oral route is erratic and the oral bioavailability is very low due to an

extensive hepatic first-pass metabolism. It may be given by suppository, intravenous

or intramuscular injection.

Perphenazinehas similar indications and kinetics to prochlorperazine, and has

been shown to be effective in the prevention and treatment of PONV. It is associ-

ated with a higher incidence of extrapyramidal effects and increased post-operative

sedation than prochlorperazine.

Butyrophenones

Droperidol

Droperidol is the only butyrophenone that is used in anaesthetic practice. However

this agent is no longer available in the UK.