<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>The hydrochloride salt form of rolapitant, an orally bioavailable, centrally-acting, selective, neurokinin 1 receptor (NK1-receptor) antagonist with potential antiemetic activity. Upon oral administration, rolapitant competitively binds to and blocks the activity of the NK1-receptor in the central nervous system, by inhibiting the binding of the endogenous ligand, substance P (SP). This may prevent both SP-induced emesis and chemotherapy-induced nausea and vomiting (CINV). The interaction of SP with the NK1-receptor plays a key role in the induction of nausea and vomiting caused by emetogenic cancer chemotherapy. Compared to other NK1-receptor antagonists, rolapitant has both a more rapid onset of action and a much longer half-life.</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>