Background: Palonosetron (Aloxi(®), Onicit(®)) is a pharmacologically unique 5-HT3 receptor antagonist (RA) approved as a single IV injection for the prevention of nausea and vomiting induced by chemotherapy (CINV) of either moderate or highly emetogenic potential (MEC and HEC, respectively). An oral palonosetron formulation has been developed and compared to the IV formulation.
Methods: In this multinational, multicenter, double-blind, double-dummy, dose-ranging trial, 651 patients were randomly assigned to receive one of the following as a single dose prior to moderately emetogenic chemotherapy: oral palonosetron 0.25, 0.50, and 0.75 mg or IV palonosetron 0.25 mg. Patients were also randomized (1:1) to receive dexamethasone 8 mg IV or matched placebo on day 1. The primary endpoint was complete response (CR; no emesis, no rescue therapy) during the acute phase (0-24 h).
Results: Acute CR rates were 73.5, 76.3, 74.1, and 70.4 % for all patients receiving the palonosetron 0.25, 0.50, and 0.75 mg oral doses, and for IV palonosetron 0.25 mg, respectively; delayed CR (24-120 h) rates were 59.4, 62.5, 60.1, and 65.4 %, and overall CR (0-120 h) rates were 53.5, 58.8, 53.2, and 59.3 %, respectively. The addition of dexamethasone improved emetic control (acute CR rate) by at least 15 % for all groups except oral palonosetron 0.25 mg, where the acute CR improvement was approximately 7 %. Adverse events were similar in nature, incidence, and intensity for all oral and IV palonosetron groups, and were the expected adverse events for 5-HT3 RAs (primarily headache and constipation).
Conclusion: Oral palonosetron has a similar efficacy and safety profile as IV palonosetron 0.25 mg and may be the preferred formulation in certain clinical situations. Among the tested oral treatments, a palonosetron 0.50-mg oral dose has been favored for the prevention of CINV in patients receiving moderately emetogenic chemotherapy due to a numerical gain in efficacy without a side effect disadvantage.