<p>Prochlorperazine is a dopamine &amp; histamine antagonist. The mechanism of antiemetic activity is due to the blockade of histamine H, &amp; dopamine D2 neurotransmitter receptors in the chemoreceptor trigger zone and vomiting centre. It also has a weak anticholinergic effect and prevents acid reflux by increasing the tone of the lower oesophageal sphincter.</p>