Anaes · Anaesthetic adjuncts

Antiemetics for PONV — 5-HT3 antagonists, dexamethasone, droperidol, NK1 antagonists

Also known as Ondansetron · Dexamethasone · Droperidol · Aprepitant · Postoperative nausea and vomiting prophylaxis · Apfel risk score

Postoperative nausea and vomiting remains the most common cause of patient dissatisfaction after anaesthesia and the anaesthetist controls most of its determinants, so a working command of the four antiemetic drug classes and of the risk-stratified strategy that deploys them is a high-yield applied pharmacology block. The framework rests on five exam-critical ideas: the four classes act at four distinct receptor targets (the 5-HT3 antagonists such as ondansetron block serotonin at the chemoreceptor trigger zone and the gut, the corticosteroid dexamethasone suppresses central inflammatory and prostaglandin pathways, the butyrophenone droperidol blocks dopamine D2 receptors, and the NK1 antagonists such as aprepitant block substance P), and each class has a signature adverse effect the anaesthetist must know (ondansetron prolongs the QT interval, droperidol carries a Food and Drug Administration black-box warning for QT prolongation, dexamethasone is remarkably safe and inexpensive, and the NK1 antagonists are long-acting but expensive); the Apfel score stratifies risk from four simple factors (female sex, non-smoker, history of PONV or motion sickness, and postoperative opioids) and predicts an incidence from about 10 per cent with no factors up to about 80 per cent with all four; prophylaxis is reserved for moderate-to-high-risk patients and is given as combination therapy using two or three agents from different classes, because no single agent is effective enough to use alone in a high-risk patient; and rescue treatment of breakthrough PONV uses a drug from a different class than the prophylaxis, because intraoperative prophylaxis has already occupied the first receptor. Built on the dexamethasone-versus-ondansetron PONV trial (Loomba 2026), the dexamethasone perioperative analgesia review (Pantke 2026), the opioid-sparing anaesthesia and PONV after breast surgery study (Sung 2026), the aprepitant neuroprotection review (Akbarpournikghalb 2026), the immediate versus delayed dexamethasone implantation study (Chen 2026), and the oliceridine versus sufentanil PONV trial (Liu 2026).