Overview

Ondansetron is well absorbed and undergoes some first-pass metabolism in the gastrointestinal tract. The average bioavailability of healthy subjects was around 56%, and it increased slightly with the presence of food and higher doses, but not with antacids. Ondansetron has a volume of distribution of 1.92.6 L/kg, indicating that the majority of the drug is absorbed by human tissues. Red blood cel… ... See More Ondansetron is well absorbed and undergoes some first-pass metabolism in the gastrointestinal tract. The average bioavailability of healthy subjects was around 56%, and it increased slightly with the presence of food and higher doses, but not with antacids. Ondansetron has a volume of distribution of 1.92.6 L/kg, indicating that the majority of the drug is absorbed by human tissues. Red blood cells also transport circulating drugs. Plasma protein binding is 70%, and it can easily cross the membrane. The biotransformation pathway denotes that hydroxylation on the indole ring is the primary metabolic pathway, followed by glucuronide or sulfate conjugation. The liver extensively metabolizes ondansetron, which is excreted in urine (about 65%) and feces (35%). The half-life of plasma is 3.5 hours. See Less