Abarelix is a potent gonadotrophin-releasing hormone (GnRH) antagonist, used for prostate cancer treatment.

Abarelix (30 and 300 µg/mL) and cetrorelix cause significantly increased histamine release[1]. Abarelix is the firstGnRH antagonist to be developed, and can produce rapid and sustained decreases in testosterone to castrate levels without the need for co-administration of an antiandrogen, and with a very low complication rate in the short term[2]. Abarelix demonstrates to promptly and substantially reduce follicle-stimulating hormone levels to lower than LHRH agonist. Abarelix does not cause a surge in serum testosterone that can precipitate a flare phenomenon or worsening of disease, particularly dangerous for patients with metastatic, symptomatic disease, and produces medical castration more quickly[3].

[1]. Koechling W, et al. 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. 2010 Oct;70(4):580-7. [2]. Kirby RS, et al. Abarelix and other gonadotrophin-releasing hormone antagonists in prostate cancer. BJU Int. 2009 Dec;104(11):1580-4. [3]. Debruyne F, et al. Abarelix for injectable suspension: first-in-class gonadotropin-releasing hormone antagonist for prostate cancer. Future Oncol. 2006 Dec;2(6):677-96.