FDA Approved Sexual & Reproductive Health

Degarelix

also known as: Firmagon

Ferring's Firmagon — a GnRH antagonist for advanced prostate cancer that achieves castrate testosterone within 3 days, eliminating the clinical flare risk of GnRH-agonist therapy in patients with symptomatic bone metastases or impending spinal cord compression.

A synthetic GnRH-receptor antagonist with multiple non-natural amino acid substitutions designed for sustained-release SC depot delivery. FDA-approved as Firmagon in 2008 for advanced prostate cancer. Key clinical advantage over GnRH agonists: testosterone suppression is immediate (castrate levels by day 3 versus 2–4 weeks with leuprolide) with no initial flare, making it preferred in patients with symptomatic skeletal metastases or spinal cord compression risk where a GnRH-agonist flare could cause acute deterioration.

Mechanism of action

Competitive GnRHR antagonism produces immediate blockade of LH and FSH release; testosterone falls to castrate levels (<50 ng/dL) in approximately 3 days in >96% of patients versus 2–4 weeks with leuprolide. No agonist flare means no transient testosterone surge and no tumor-flare-associated worsening of bone pain, obstructive uropathy, or cord-compression symptoms.

Primary uses

  • Advanced prostate cancer — first-line ADT
  • Preferred ADT in patients with symptomatic bone metastases or impending cord compression
  • Alternative to GnRH agonists in patients at risk of tumor flare

Typical dosing

240 (loading), 80 (maintenance) mg monthly maintenance after initial loading dose (subcutaneous (abdomen))

Loading dose: 240 mg total, administered as two separate 120 mg SC injections (each 40 mg/mL). Maintenance: 80 mg SC monthly (20 mg/mL). Injection-site reactions are common (~35%) and typically self-limiting.

Regulatory status

FDA-approved as Firmagon (degarelix, Ferring Pharmaceuticals, approved December 2008) for treatment of advanced prostate cancer. Loading dose of 240 mg SC (two 120 mg injections) at cycle initiation, followed by monthly 80 mg SC maintenance doses.

References

  1. [fda-pi] Firmagon (degarelix) Prescribing Information. Ferring Pharmaceuticals.
  2. [pubmed] Klotz L, et al. "The efficacy and safety of degarelix: a 12-month, comparative, randomized, open-label, parallel-group phase III study in patients with prostate cancer." BJU Int, 2008;102:1531-1538 (pivotal CS21 trial).

Related peptides

Leuprolide

The prototypical long-acting GnRH agonist, FDA-approved across multiple formulations (Lupron Depot, Eligard, Fensolvi, Camcevi) for advanced prostate cancer, endometriosis, central precocious puberty, uterine fibroids, and IVF protocols.

Triptorelin

A widely used long-acting GnRH agonist — FDA-approved as Trelstar for advanced prostate cancer and as Triptodur for pediatric central precocious puberty; approved internationally (Decapeptyl, Gonapeptyl) for endometriosis, uterine fibroids, and female infertility protocols.

Goserelin

AstraZeneca's Zoladex — a long-acting GnRH agonist delivered as a subcutaneous biodegradable implant. FDA-approved for advanced prostate cancer, advanced breast cancer in premenopausal women, endometriosis, and endometrial thinning prior to ablation.

Cetrorelix

Merck Serono's Cetrotide — a GnRH antagonist used during IVF controlled ovarian stimulation to block premature LH surges. Unlike GnRH agonists, produces immediate gonadotropin suppression without a flare, shortening IVF cycles.

Ganirelix

Organon/Merck's Ganirelix Acetate (formerly Antagon; Orgalutran internationally) — a GnRH antagonist functionally equivalent to cetrorelix for IVF LH-surge prevention, dosed as a daily fixed 250 mcg SC injection.
Disclaimer

This entry is for educational purposes only and does not constitute medical advice. Dosing information reflects published regulatory or research data and is not a recommendation. Many compounds described here are not approved for human use in the United States. Consult a licensed medical professional before considering any peptide therapy.