Comparison of agents
Clinicians should note that studies suggest that there are no major differences in efficacy or toxicity of the three first-generation 5-HT3 receptor antagonists (dolasetron, granisetron, and ondansetron) in the treatment of acute CINV. These three agents are equivalent in efficacy and toxicity when used in appropriate doses.;[46,47,48][Level of evidence: I] Although these agents have been shown to be effective in the first 24 hours postchemotherapy (acute phase), they have not been demonstrated to be effective in days 2 to 5 postchemotherapy (delayed phase).[29,49,50]
Palonosetron, the second-generation 5-HT3 receptor antagonist, has been approved for the control of delayed emesis for patients receiving moderately emetogenic chemotherapy.;[Level of evidence: I]
Despite the use of both first-generation and second-generation 5-HT3 receptor antagonists, the control of acute CINV, and especially delayed N&V, is suboptimal, and there is considerable opportunity for improvement with either the addition or substitution of new agents in current regimens.[Level of evidence: II];[Level of evidence: I][49,50]
Substance P Antagonists (NK-1 Receptor Antagonists)
The initial clinical studies using the NK-1 receptor antagonists [52,53,54][Level of evidence: I] demonstrated that the addition of an NK-1 receptor antagonist (CP-122,721, CJ-11,794, MK-0869 [aprepitant]) to a 5-HT3 receptor antagonist plus dexamethasone prior to cisplatin chemotherapy improved the control of acute emesis compared with a 5-HT3 receptor antagonist plus dexamethasone and improved the control of delayed emesis compared with placebo. In addition, as a single agent, aprepitant (MK-0869) had an effect similar to that of ondansetron on cisplatin-induced acute emesis but was superior in the control of delayed emesis. Subsequent studies [56,57][Level of evidence: I] showed that the combination of aprepitant and dexamethasone was similar to a 5-HT3 receptor antagonist plus dexamethasone in controlling acute emesis but was inferior in controlling acute emesis compared with triple therapy (aprepitant, 5-HT3 receptor antagonist, and dexamethasone). These studies also confirmed the improvement of delayed emesis with the use of aprepitant compared with placebo. Two studies [31,58][Level of evidence: I] have also shown an improvement in cisplatin-induced delayed emesis with the combination of aprepitant and dexamethasone compared with dexamethasone alone, with the improvement maintained over repeat cycles of cisplatin chemotherapy.