AR-A 2 is a selective 5-HT1B receptor antagonist, with a high affinity to guineapig cortex 5HT1B 1D and recombinant guineapig 5-HT1B receptors (Ki: 0.24 and 0.47 nM) and with 10-fold lower affinity to guineapig 5-HT1D receptor (Ki: 5 nM).
Axelopran(TD-1211) is potentially useful for the treatment of opioid-induced constipation, it is a potent, selective, and peripherally-restricted μ-, κ-, and δ-opioid receptor antagonist.
Rolapitant, also known as SCH-619734, is 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, thereby 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.