ONDIROX-P Pantoprazole 40mg + Ondansetron 4mg is a combination of two medicines: Pantoprazole and Ondansetron. Pantoprazole is a proton pump inhibitor (PPI). It works by reducing the amount of acid in the stomach which helps in the relief of acid-related indigestion and heartburn. Ondansetron is an antiemetic (anti-nausea medicine). It inhibits the action of serotonin, a chemical messenger that can trigger nausea and vomiting..