In a palliative care patient receiving diamorphine for pain who has been vomiting for 24 hours despite haloperidol, which antiemetic is most appropriate?

• A. Haloperidol
• B. Cyclizine
• C. Metoclopramide
• D. Levomepromazine

Answer: (D)

When vomiting persists despite an antiemetic from the same drug class, switching to an agent with a different mechanism and broad antiemetic action is most effective in palliative care. Levomepromazine fits this need because it is a potent phenothiazine antiemetic that blocks dopamine D2 receptors in the chemoreceptor trigger zone and also has activity on 5-HT receptors, histamine receptors, and alpha-adrenergic pathways. This broad receptor blockade makes it especially effective for opioid-induced nausea and for emesis that has not responded to a standard antiemetic like haloperidol. It can also provide sedation, which can be beneficial in a distressed patient with advanced disease. In contrast, continuing haloperidol would not address the persistent vomiting, while cyclizine or metoclopramide offer less robust control in this scenario and may have limited efficacy or tolerability. Therefore, levomepromazine is the most appropriate choice.