For the prevention of acute and delayed nausea and vomiting associated with initial and repeat courses of moderately emetogenic cancer chemotherapy, as well as prevention of acute nausea and vomiting associated with highly emetogenic cancer chemotherapy. Also used for the prevention of postoperative nausea and vomiting for up to 24 hours post operation.
Palonosetron is a selective serotonin 5-HT<sub>3</sub> receptor antagonist. The antiemetic activity of the drug is brought about through the inhibition of 5-HT<sub>3</sub> receptors present both centrally (medullary chemoreceptor zone) and peripherally (GI tract). This inhibition of 5-HT<sub>3</sub> receptors in turn inhibits the visceral afferent stimulation of the vomiting center, likely indirectly at the level of the area postrema, as well as through direct inhibition of serotonin activity within the area postrema and the chemoreceptor trigger zone. Alternative mechanisms appear to be primarily responsible for delayed nausea and vomiting induced by emetogenic chemotherapy, since similar temporal relationships between between serotonin and emesis beyond the first day after a dose have not been established, and 5-HT<sub>3</sub> receptor antagonists generally have not appeared to be effective alone in preventing or ameliorating delayed effects. It has been hypothesized that palonosetron's potency and long plasma half-life may contribute to its observed efficacy in preventing delayed nausea and vomiting caused by moderately emetogenic cancer chemotherapy.
A single intravenous dose of palonosetron at 30 mg/kg (947 and 474 times the human dose for rats and mice, respectively, based on body surface area) was lethal to rats and mice. The major signs of toxicity were convulsions, gasping, pallor, cyanosis and collapse.
Low oral bioavailability.
Approximately 40 hours
After a single intravenous dose of 10 mcg/kg [14C]-palonosetron, approximately 80% of the dose was recovered within 144 hours in the urine
* 8.3 ± 2.5 L/kg
* 160 +/- 35 mL/h/kg