Josie is a 5-year old patient who presents to the clinic with a 48-hour history of nausea, vomiting, and some diarrhea. She is unable to keep fluids down and her weight is 4 pounds less than her recorded weight. Besides IV fluids, her exam warrants the use of an anti-nausea medication. Which of the following would be the most appropriate drug to order for Josie?

A. Prochlorperazine (Compazine): Prochlorperazine is a dopamine antagonist used for nausea and vomiting in older children and adults, but it is not preferred in young children due to increased risk of extrapyramidal side effects, sedation, and potential respiratory depression. Safety concerns limit its use in a 5-year-old patient. B. Meclizine (Antivert): Meclizine is an antihistamine primarily used for motion sickness and vertigo-related nausea. Its efficacy in acute gastroenteritis or viral-induced vomiting in young children is limited, and sedation is a common adverse effect, making it less appropriate for Josie’s presentation. C. Promethazine (Phenergan): Promethazine is effective as an antiemetic but carries a black box warning for use in children under 2 years due to risk of severe respiratory depression. In children aged 2–5 years, it still poses significant risks including sedation, respiratory depression, and extrapyramidal effects, so safer alternatives are preferred. D. Ondansetron (Zofran): Ondansetron is a serotonin 5-HT3 receptor antagonist that is effective and safe for treating nausea and vomiting in children. It can be administered orally or intravenously, has minimal sedation risk, and is commonly used in pediatric patients with gastroenteritis or chemotherapy-induced vomiting. It helps prevent further dehydration when combined with IV fluids, making it the most appropriate choice for Josie.