Ondansetron
Ondansetron. 5-HT3 receptor antagonist — blocks vagal afferent emetic signaling from the GI tract + chemoreceptor trigger zone. First-line for… Oral half-life 3.4 h.
5-HT3 receptor antagonist — blocks vagal afferent emetic signaling from the GI tract + chemoreceptor trigger zone. First-line for chemotherapy-induced + post-operative nausea. CYP3A4/2D6 substrate. QT prolongation at IV doses ≥ 16 mg.
PK: F corrected 0.65 to the stated 71% for the oral solution; the stored value matched neither that nor the 58% rectal figure in the same sentence, though it is close to their average. This record supplies ONE OF THE FEW GENUINE PUBLISHED ABSORPTION RATES in the whole audit: "Mean absorption half-lives were 0.66, 1.1, and 0.75 hr after the oral, colonic, and rectal administrations", giving 1.05 /h orally — the stored 2 /h was about twice that and equals the drug time to peak. V 160 L appears in no abstract; 127 L is 1.81 L/kg measured at steady state after intravenous dosing. THE EFFECT-COMPARTMENT VALUE IS REMOVED BECAUSE IT CONTRADICTS THE PUBLISHED MODEL STRUCTURE, not merely because it is unsourced: the definitive analysis fits "a linear concentration-response model", which is direct and undelayed by construction. The record own note already said no such value exists; that claim now has positive evidence. A PREVIOUS FIX WAS INCOMPLETE — the fabricated palonosetron citation the note says was removed is still in the reference list, and is removed here. The intramuscular route is dropped as declared but unparameterised.
Pharmacokinetics
- Oral — t½ 3.4 h · F 71% · ka 1.05 h⁻¹ · Vd 127 L
- IV — t½ 3.4 h · F 100% · Vd 127 L
Sources: PMID:1531044, PMID:31378962, PMID:7586904