Anatomical Therapeutic Chemical Classification System
Aprepitant is a selective high-affinity antagonist at human substance P neurokinin 1 (NK1) receptors.
Fosaprepitant is the prodrug of aprepitant and when administered intravenously is converted rapidly to aprepitant. The contribution of fosaprepitant to the overall antiemetic effect has not fully been characterised, but a transient contribution during the initial phase cannot be ruled out.