fosaprepitant + ondansetron + dexamethasone

A combination antiemetic regimen consisting of fosaprepitant (a neurokinin-1 receptor antagonist), ondansetron (a 5-HT3 receptor antagonist), and dexamethasone (a corticosteroid). This triple therapy is primarily used for the prevention of chemotherapy-induced nausea and vomiting (CINV) in patients receiving highly emetogenic chemotherapy (HEC) or moderately emetogenic chemotherapy (MEC). Fosaprepitant is administered as a single intravenous dose (150 mg), which is rapidly converted to aprepitant in the body. The regimen typically involves: - Fosaprepitant: 150 mg administered as a single intravenous dose on day 1 - Ondansetron: Administered either intravenously or orally - Dexamethasone: Administered with dose adjustments when combined with fosaprepitant due to drug interactions Clinical trials have shown that this triple therapy significantly improves complete response rates (defined as no vomiting and no use of rescue therapy) compared to regimens without fosaprepitant. In one study, the complete response rate in the delayed phase was 78.9% with the fosaprepitant regimen versus 68.5% with ondansetron and dexamethasone alone. When administering this combination, it's important to note that fosaprepitant increases dexamethasone exposure. The oral dexamethasone dose on days 1 and 2 should be reduced by approximately 50% when coadministered with fosaprepitant 150 mg IV to achieve appropriate dexamethasone levels. This combination has been studied primarily in adults but is increasingly being used in pediatric populations as well. For elderly patients (≥65 years), the efficacy and safety are comparable to those seen in younger patients, with no dosage adjustment necessary. However, dosage adjustments may be needed for patients with severe renal insufficiency. As fosaprepitant is rapidly converted to aprepitant, drug interactions following administration of fosaprepitant are likely to occur with drugs that interact with oral aprepitant. Aprepitant is a substrate, a weak to moderate inhibitor, and an inducer of CYP3A4, as well as a moderate inducer of CYP2C9. Caution should be exercised when administering this combination with other medications metabolized by CYP3A4.