Fosnetupitant

The fosnetupitant in this drug combination is a selective P/neurokinin-1 (NK-1) receptor antagonist.

Netupitant, the active moiety of fosnetupitant, is a selective neurokinin 1 (NK1) receptor antagonist with antiemetic activity. Netupitant competitively binds to and blocks the activity of the human substance P/NK1 receptors in the central nervous system (CNS), inhibiting NK1-receptor binding of the endogenous tachykinin neuropeptide substance P (SP), which results in the prevention of chemotherapy-induced nausea and vomiting (CINV). Substance P is found in neurons of vagal afferent fibers innervating the brain-stem nucleus tractus solitarii and the area postrema, which contains the chemoreceptor trigger zone (CTZ), and may be present at high levels in response to chemotherapy. The NK-receptor is a G-protein receptor coupled to the inositol phosphate signal-transduction pathway and is found in both the nucleus tractus solitarii and the area postrema.

Netupitant demonstrated 92.5% NK1 receptor occupancy at 6 hours, with 76% occupancy at 96 hours.