Degarelix

FDA-approved GnRH receptor antagonistEstablished

Degarelix is an FDA-approved GnRH receptor antagonist. Degarelix binds GnRH receptors on pituitary gonadotrophs competitively and reversibly, immediately blocking the receptor rather than first overstimulating it. Luteinising hormone and follicle-stimulating hormone fall within hours and testosterone follows, avoiding the testosterone flare and the tumour-symptom worsening that can accompany initiation of a GnRH agonist.

Calculate Dose

For research use only.

Key Facts

CAS: 214766-78-6
Molecular Weight (MW): 1632.3 g/mol
Half-life: —
FDA status: Approved
Evidence level: FDA Approved
Human dose established: Yes
Administration Route: Subcutaneous
Frequency: Starting dose once, then every 28 days
Last updated: Nov 7, 2026
Reviewed: Nov 7, 2026

Research summary

Gonadotropin-releasing hormone receptor antagonist approved for advanced hormone-sensitive prostate cancer. Unlike GnRH agonists it lowers testosterone without an initial surge.

Research evidence

Regulatory review (FDA label)1 reviewed source
Controlled human trials1 reviewed source
Early or uncontrolled human studiesNone in reviewed sources
Lab & animal studiesNone in reviewed sources

How it works

Each step shows whether the sources Peptide Library has reviewed include that kind of research. Counts are reviewed sources, not every study ever published. Reviews and programme summaries that describe human use are shown as "reported", not as trials, and registered trials without published results are listed but not counted. A higher step means research has progressed further; it does not mean a compound works better or is safer. Compounds whose evidence has not been reviewed yet show "Not reviewed" instead of a guess.

Peptide Library's Degarelix profile summarises 5 cited studies listed in the Science section, the compound's regulatory status, and research-protocol parameters reported for it. It is a research reference, not medical advice.

Degarelix dosage evidence

Degarelix has an FDA-approved human dosage for advanced prostate cancer. The FIRMAGON label gives a 240 mg starting dose as two 120 mg injections under the skin of the abdomen, then 80 mg as one injection every 28 days, starting 28 days after the first dose.

FDA Approved

Dosage evidence summary for Degarelix
Human dosing established	Yes
Route	Subcutaneous
Frequency	Starting dose once, then every 28 days
Duration studied	Long-term
Evidence level	FDA Approved
Last reviewed	2026-11-07

Research-reported dosing

Doses as studied, one row per regimen. Different trials used different regimens; they are listed separately rather than averaged.

Research-reported dosing for Degarelix, one row per studied regimen
Study / context	Population	Dose	Route	Frequency	Duration	Outcome studied	Source
FDA label — FIRMAGON, advanced prostate cancerFDA-approved label · FDA prescribing information	Patients with advanced prostate cancer	Starting dose 240 mg as two 120 mg injections (40 mg/mL); maintenance 80 mg as one injection (20 mg/mL)	Subcutaneous, abdomen only	Maintenance every 28 days, the first 28 days after the starting dose	Long-term	Treatment of advanced prostate cancer	FIRMAGON (degarelix for injection) — FDA prescribing information (Ferring), DailyMed
CS21 — phase 3 trial against leuprolide (Klotz et al., 2008)Clinical trial · Phase 3 randomised open-label trial	Men with prostate adenocarcinoma needing androgen deprivation (n=610)	240 mg start, then 80 mg or 160 mg monthly; comparator leuprolide 7.5 mg intramuscularly monthly	Subcutaneous	Monthly	12 months	Testosterone at or below 0.5 ng/mL from day 28 to day 364 in 97.2% (240/80 mg), 98.3% (240/160 mg) and 96.4% (leuprolide); injection-site reactions 40% with degarelix against under 1% with leuprolide	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.

Where sources disagree

The starting and maintenance doses use different concentrations (40 mg/mL and 20 mg/mL). The label says FIRMAGON is given by a healthcare professional only.
The label warns of hypersensitivity reactions including anaphylaxis, QT interval prolongation with androgen deprivation therapy, and embryo-fetal toxicity.
In the CS21 trial testosterone was at or below 0.5 ng/mL 3 days after the first dose in about 96% of men on degarelix and in none on leuprolide. FIRMAGON is labelled as a GnRH receptor antagonist; leuprolide, the comparator, is a GnRH agonist.

Degarelix dosage in published studies and labels →

Sequence & molecular data

Sequence and molecular data for Degarelix
Molecular formula	C82H103ClN18O16
Molecular weight	1632.3 g/mol
CAS number	214766-78-6
PubChem CID	16136245
FDA UNII	SX0XJI3A11
ChEMBL	CHEMBL415606
DrugBank	DB06699

Identifiers link to the public PubChem, FDA Substance Registration (UNII), ChEMBL and DrugBank records for the same entity.

Science

Mechanism of Action

Degarelix binds GnRH receptors on pituitary gonadotrophs competitively and reversibly, immediately blocking the receptor rather than first overstimulating it. Luteinising hormone and follicle-stimulating hormone fall within hours and testosterone follows, avoiding the testosterone flare and the tumour-symptom worsening that can accompany initiation of a GnRH agonist.

Studies

Research statistics

308 PubMed publications · 50.3% human clinical research · 144 registered trials

Counts of published research through 2026-11-01, not evidence that it works. Publications by year, study types and trials · How publications are counted

Regulatory & research status

Degarelix is an FDA-approved product for specific labelled indications. Approval does not extend to the research contexts described on this page, and approved products are prescription medicines.

Regulatory and research status for Degarelix
FDA status	Approved
Research status	Approved product (see FDA status)
Availability	Prescription-Only
WADA (sport)	Unknown / Not Listed
Library classification	FDA-Approved

How FDA approval, compounding and research-only status differ

Benefits

—

Degarelix side effects

No side effects listed yet for this entry.

Storage & stability

This compound is not supplied as a powder to be mixed, so the freeze-dried powder and reconstitution handling described for research peptides does not apply. Storage conditions are product-specific: follow the label or packaging of the product itself.

Degarelix: frequently asked questions

What is Degarelix?

Gonadotropin-releasing hormone receptor antagonist approved for advanced hormone-sensitive prostate cancer. Unlike GnRH agonists it lowers testosterone without an initial surge.

How does Degarelix work?

Is Degarelix FDA approved?

Yes. Degarelix is approved by the FDA, and approved products are prescription medicines. Approval is always for specific indications studied in clinical trials, so an approved status does not mean the compound is approved for every use it is discussed for. Research-chemical material sold under the same name is not the approved product.

What peptides are similar to Degarelix?

Compounds most often compared with Degarelix include Cetrorelix, Ganirelix, Leuprolide and Gonadorelin. They are grouped by shared mechanism or research area rather than by equivalence, and their regulatory status and evidence base differ.

References

Related research, comparisons & guides

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Compiled by Peptide Library Editorial · Reviewed Aug 30, 2026 · Updated Nov 7, 2026 · Version 2

This Degarelix profile is compiled from published literature (5 cited studies linked above), public regulatory records and chemical registries. It describes what research reports; it is not medical advice, and nothing here is a dosing recommendation for humans. Peptide Library does not sell peptides. Editorial policy · How profiles are compiled · Report an error

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