Evidence review: Open Peptide Project (verified against primary PubMed, ClinicalTrials.gov & FDA records) · Last checked 2026-10-27. ← Back to Evidence Library

Degarelix (Firmagon): what the evidence says

Name: Degarelix (Firmagon)
Published: 2026-10-27

At a glance

What it is: a lab-made GnRH antagonist peptide (10 amino acids) that blocks the pituitary's GnRH receptor, quickly cutting testosterone without the initial surge seen with agonists like leuprolide. Monthly injection by a clinician. FDA-approved Dec 2008 as Firmagon (Ferring). ^{R1, R2}

What the evidence says: in a 610-man phase 3 trial, testosterone was at castration level by day 3 in 96% on degarelix vs 0% on leuprolide, with no surge. ^R3 A head-to-head heart-safety trial (PRONOUNCE) was stopped early and found no significant difference. ^R4

Biggest risks: injection-site reactions (about 40%), hypersensitivity, and QT prolongation from androgen deprivation. ^{R3, R2}

Rating


Human Human evidence	Strong for testosterone suppression in prostate cancer ^{R3, R5} · Inconclusive cardiovascular comparison ^R4 · No human data for non-cancer uses
Animal Animal / lab evidence	Not reviewed for this page
Regulatory	FDA-approved (NDA 022201) · not on the 503A/503B lists or FDA's safety-risk page · WADA 2026 S2.2.1 names GnRH agonists (males); degarelix, an antagonist, is not named ^{R1, R6, R7, R8, R9}
Established human dose	Label dose given by a clinician (see Study details and the FDA label)

Evidence verdict: Lowering testosterone in advanced prostate cancer: Strong (FDA-approved; phase 3 vs leuprolide) · Heart-safety advantage over leuprolide: not shown (trial stopped early) · Anything else: No human data

This page reports what studies used. It is not dosing advice.

Legend: HUMAN data · ANIMAL / LAB data · UNKNOWN · UNVERIFIED: not yet confirmed against a primary source

About the evidence: the pivotal trial and PRONOUNCE were sponsored by Ferring. PRONOUNCE was stopped early, so it could not settle the heart question. ^{R3, R4}

What is it?

GnRH from the brain tells the pituitary to drive testosterone. Agonists overstimulate then shut this down (with an early surge); degarelix blocks it at once. Related pages: Leuprolide, Gonadorelin.

Does it work?

Human Klotz 2008 (CS21): 610 men; testosterone suppressed by day 3 in 96% vs 0% on leuprolide; suppression maintained over 1 year comparably. ^R3
Human 5-year extension: long-term control maintained. ^R5
Human PRONOUNCE: 545 men with prostate cancer and heart disease; major cardiovascular events 5.5% vs 4.1% (HR 1.28, p = 0.53). ^{R4, R10}

Is it safe?

Human Injection-site reactions about 40% in CS21. ^R3
Human Label warnings: hypersensitivity including anaphylaxis; QT prolongation with androgen deprivation therapy. ^R2
Human Expected effects of low testosterone (hot flashes, bone loss, metabolic changes). ^R2

Gray-market "degarelix": extra risks

A gray-market vial has no quality control and no guarantee of identity, strength or sterility. We test retail vials blind under the Open Peptide Standard; see /tests/. A passing test covers one batch on one date and does not mean the compound is safe. Shutting down testosterone outside cancer care has no studied benefit.

Is it legal?

US (FDA): prescription only, given by a healthcare professional. ^{R2, R1}
Athletes: not named on WADA's 2026 list; S2.2.1 covers GnRH agonists in males. UNVERIFIED how WADA treats antagonists. ^R9

Study details

These are amounts researchers used, not recommendations.

Study	People / model	Route	Amount used	Follow-up	Reported	Citation
FDA label (Firmagon)	Men with advanced prostate cancer	SC by a clinician	240 mg start, then 80 mg every 28 days	Ongoing	Approved use	FDA label
Klotz 2008 (CS21)	610 men	SC monthly	240 mg then 80 or 160 mg	1 year	96% suppressed by day 3	PMID 19035858
PRONOUNCE 2021	545 men with ASCVD	SC monthly vs leuprolide	Label regimen	~1 year (stopped early)	MACE 5.5% vs 4.1%	PMID 34459214

Full reference list (PubMed, CT.gov, FDA and WADA checked Oct 26, 2026)

^R1 Drugs@FDA, Firmagon, Ferring, approved Dec 24, 2008, application 022201 (openFDA drugsfda record checked Oct 26, 2026). https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=022201
^R2 Firmagon (degarelix) for injection prescribing information, label published Feb 1, 2024 (DailyMed, checked Oct 26, 2026). https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=ab11dd8a-0fd9-4013-89ab-e114557c7e4b
^R3 Klotz L, et al. BJU Int. 2008. PMID 19035858
^R4 Lopes RD, et al. Circulation. 2021. PMID 34459214
^R5 Crawford ED, et al. Urology. 2014. PMID 24661333
^R6 FDA, 503A bulk drug substances categories list (updated May 14, 2026). https://www.fda.gov/media/94155/download
^R7 FDA, 503B bulk drug substances categories list (updated Mar 21, 2025). https://www.fda.gov/media/94164/download
^R8 FDA, Certain bulk drug substances for use in compounding that may present significant safety risks (content current Apr 22, 2026). https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks
^R9 WADA. The 2026 Prohibited List, S2.2.1. https://www.wada-ama.org/sites/default/files/2025-09/2026list_en_final_clean_september_2025.pdf
^R10 ClinicalTrials.gov NCT02663908, Ferring, PRONOUNCE, degarelix vs leuprolide cardiovascular safety, phase 3, terminated early (CT.gov API v2, checked Oct 26, 2026). https://clinicaltrials.gov/study/NCT02663908

Disclaimer

This page is for education and harm reduction, not medical advice or a recommendation to use Degarelix (Firmagon). It is a prescription injection given by a healthcare professional for prostate cancer. Talk to your oncologist, especially if you have heart disease or a heart rhythm problem. Report problems to FDA MedWatch (https://www.fda.gov/safety/medwatch).