Abarelix is a synthetic third generation gonadotropin-releasing hormone receptor (GnRHR) antagonist (IC50 = 3.5 nM in HEK293 cells expressing the human receptor).1,2 It increases histamine release from rat peritoneal mast cells in vitro and from a human skin model ex vivo.3,4 In vivo, abarelix (200 μg/kg) decreases plasma luteinizing hormone (LH) levels six hours post-treatment in castrated rats, with levels returning to baseline within 24 hours.3 Abarelix (2 mg/kg) also transiently decreases plasma testosterone levels in intact rats, with levels returning to baseline within seven days post-treatment. Formulations containing abarelix have previously been used in the treatment of advanced prostate cancer.
|1. Tan, O., and Bukulmez, O. Biochemistry, molecular biology and cell biology of gonadotropin-releasing hormone antagonists. Curr. Opin. Obstet. Gynecol. 23(4), 238-244 (2011).|2. Jiang, G., Stalewski, J., Galyean, R., et al. GnRH antagonists: A new generation of long acting analogues incorporating p-ureido-phenylalanines at positions 5 and 6. J. Med. Chem. 44(3), 453-467 (2001).|3. Broqua, P., Riviere, P.J.-M., Conn, P.M., et al. Pharmacological profile of a new, potent, and long-acting gonadotropin-releasing hormone antagonist: Degarelix. J. Pharmacol. Exp. Ther. 301(1), 95-102 (2002).|4. Koechling, W., Hjortkjaer, R., and TankÓ, L.B. Degarelix, a novel GnRH antagonist, causes minimal histamine release compared with cetrorelix, abarelix and ganirelix in an ex vivo model of human skin samples. Br. J. Clin. Pharmacol. 70(4), 580-587 (2010).