APD421 + ondansetron

APD421 + ondansetron is a combination drug consisting of **APD421** (the developmental code name for amisulpride when used as an antiemetic) and **ondansetron**. This combination is investigated for the **prevention and treatment of postoperative nausea and vomiting (PONV)**. APD421 (amisulpride, at low, selective doses) acts as a dopamine D2/D3 receptor antagonist, while ondansetron is a selective serotonin 5-HT3 receptor antagonist. The two drugs work via independent and additive mechanisms: amisulpride blocks dopaminergic signaling in the chemoreceptor trigger zone responsible for emesis, while ondansetron inhibits serotonin-mediated signaling involved in the vomiting reflex. This approach is designed to provide greater antiemetic efficacy than either agent alone, with both oral and intravenous formulations in clinical trial evaluation.