Palonosetron:: a unique 5-HT3-receptor antagonist for the prevention of chemotherapy-induced emesis

Palonosetron (Aloxi(TM)) is a 5-HT3-receptor antagonist antiemetic indicated for the prevention of acute and delayed nausea and vomiting following moderately emetogenic chemotherapy and for acute nausea and vomiting following highly emetogenic chemotherapy. Although it is the fourth member of this class to enter the US market, palonosetron is distinguished by distinct pharmacological characteristics. It has a higher binding affinity for the 5-HT3 receptor and a terminal serum half-life at least four times greater than any other available agent of this class (similar to 40 h). The high affinity and long half-life may explain the persistence of antiemetic effect throughout the delayed emesis risk period. The indications for palonosetron are supported by one dose-ranging study and three large, randomised, Phase III studies that all demonstrated at least equivalent activity (and in some cases, superior activity) compared to other 5-HT3-receptor antagonists. In spite of the pharmacological differences, the side effect profile of palonosetron is comparable to that of other 5-HT3-receptor antagonists. Palonosetron may prove valuable in combination therapy for delayed emesis and may be an appropriate agent for clinical settings, such as multiple-day chemotherapy, where acute emesis is repeatedly induced. Palonosetron provides a convenience advantage if multiple-day 5-HT3-receptor antagonist therapy is anticipated and is a unique addition to the antiemetic armamentarium.