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 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 antagonistsCurr. 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 6J. 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: DegarelixJ. Pharmacol. Exp. Ther.301(1)95-102(2002)