Degarelix Acetate

Degarelix is a selective gonadotrophin releasing-hormone (GnRH) antagonist. It binds to the GnRH receptors in the pituitary gland, competitively and reversibly, and this quickly lowers the release of the gonadotrophins luteinizing hormone (LH) and follicle stimulating hormone (FSH). With less LH and FSH, the testes secrete less testosterone (T). Prostatic carcinoma is known to be androgen sensitive, so it responds to treatment that removes the source of androgen.

GnRH agonists can cause an LH surge after treatment starts, followed by a testosterone surge, tumour stimulation and a possible symptomatic flare. GnRH antagonists like degarelix don't do this.

A single dose of 240 mg degarelix, followed by a monthly maintenance dose of 80 mg, quickly lowers the concentrations of LH, FSH and then testosterone. The serum concentration of dihydrotestosterone (DHT) falls in a similar way to testosterone. Degarelix achieves and maintains testosterone suppression well below the medical castration level of 0.5 ng/ml. With monthly maintenance dosing of 80 mg, testosterone stayed suppressed for at least one year in 97% of patients. No testosterone microsurges were seen after re-injection during degarelix treatment. After one year of treatment the median testosterone level was 0.087 ng/ml (interquartile range 0.06 to 0.15), N=167.