Is degarelix FDA-approved, and what does the research show?

What is degarelix?

Degarelix is a prescription cancer medicine, not a wellness, weight or performance peptide ¹. It is a GnRH receptor antagonist, a drug that blocks the receptor for gonadotropin-releasing hormone ¹. GnRH acts on receptors in the pituitary gland; blocking them lowers LH, FSH and then testosterone ¹. Lowering testosterone to castrate levels, the level left after removal of the testes, by surgery or by drugs, is called androgen deprivation therapy ⁴.

The molecule is a synthetic linear decapeptide, a chain of ten amino acids, and seven of them are unnatural forms not found in human proteins ¹. It is supplied as the acetate salt, a powder mixed with sterile water before injection ¹. Ferring Pharmaceuticals sells it in the United States as Firmagon ¹, ². Under the skin it forms a depot, a reservoir in the tissue that releases the drug slowly ¹. The label gives a median half-life of about 53 days, the time for half the drug to leave the blood ¹.

Is degarelix FDA-approved?

Yes. Degarelix is approved by FDA as the prescription medicine Firmagon, with initial U.S. approval in 2008 ¹. FDA's Drugs@FDA record shows Ferring's new drug application, NDA 022201, approved on December 24, 2008 as a new molecular entity, FDA's term for an active ingredient not approved before ². The record gives marketing status "Prescription" for both vial strengths ². The label's text was last revised in February 2020; the current DailyMed version is dated January 30, 2024 ¹.

The approved use is one. The label says Firmagon "is indicated for treatment of patients with advanced prostate cancer" ¹. The label's trial enrolled men at every stage: disease that had spread, disease grown beyond the gland, localized disease, and relapse shown by a rising PSA ¹. PSA, prostate-specific antigen, is the blood marker used to follow prostate cancer ¹. The label names no other use: not weight, muscle, longevity, wellness, fertility or athletic performance ¹.

The label says safety and effectiveness "have not been established in women" and "have not been established" in children ¹. Every form is prescription-only. The cartons are marked "Rx only," and the Patient Information calls it "a prescription medicine used in the treatment of advanced prostate cancer" ¹. The label says it "is to be administered by a healthcare professional only" ¹. The route to it is a licensed clinician's prescription ¹.

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How does degarelix work?

Degarelix blocks the GnRH receptor at once, and that is what separates it from the older prostate cancer hormone drugs ¹, ³. The label says it "binds reversibly to the pituitary GnRH receptors, thereby reducing the release of gonadotropins and consequently testosterone" ¹. Gonadotropins are the pituitary's two messenger hormones, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which tell the testes to make testosterone ¹. A single starting dose lowers LH and FSH first, then testosterone ¹.

The goal is medical castration: testosterone held "below the castration level of 50 ng/dL," nanograms per deciliter of blood ¹. In the label's trial, most men on the approved regimen reached that level within days, and none on leuprolide did by day 3, 1 percent by day 7 ¹.

Leuprolide, a different molecule with its own page, is a GnRH agonist ⁴. The two reach the same end by different routes ⁴.

The paper on the pivotal trial says degarelix has "a different mechanism of action from traditional GnRH agonists" ³. Its "immediate onset of action" suppresses testosterone faster than leuprolide, and no anti-androgen, a drug that blocks testosterone's action, is needed "to prevent the possibility of clinical 'flare'" ³. The Lupron Depot label says leuprolide initially "causes increases in serum levels of testosterone to approximately 50% above baseline" ⁵. The Firmagon label and the trial paper describe no other action of the drug, and the trial measured it in men with prostate cancer ¹, ³.

What does the research show?

The evidence sits at the top tier: FDA approval on a 620-man randomized trial, published in 2008, plus a 545-man randomized trial of heart safety published in 2021 ¹, ³, ⁴. Both trials were open-label, meaning patients and doctors knew which drug was given, and both compared degarelix with leuprolide ¹, ⁴.

Studied in men with prostate cancer: the pivotal trial, registered as NCT00295750, randomized 620 men to one of two degarelix regimens or to leuprolide for one year ¹. The 610 men treated had a median age of about 73, a range of 50 to 98, and a median starting testosterone of about 400 ng/dL ¹. By stage, 20 percent had metastatic disease, 29 percent locally advanced, 31 percent localized and 20 percent other, including PSA relapse after earlier curative treatment ¹. The primary objective was to show that degarelix achieves and maintains testosterone at or below 50 ng/dL from day 28 to day 364 ¹.

It did: on the approved regimen, 202 of 207 men held castrate testosterone for the year ¹. That is a Kaplan-Meier estimate of 97.2 percent, an estimate that allows for men who left the trial early ¹. Its 95 percent confidence interval, the range the true figure is likely to lie in, was 93.5 to 98.8 ¹. On leuprolide, 194 of 201 did, an estimate of 96.4 percent with an interval of 92.5 to 98.2 ¹.

The paper reports 98.3 percent in the third arm, a higher maintenance dose that FDA did not approve ³, ¹. It concludes that degarelix "was not inferior to leuprolide at maintaining low testosterone levels over a 1-year treatment period" ³.

The difference was speed: on day 3, 96 percent of the men on the approved regimen were at or below 50 ng/dL, against none on leuprolide ¹. On day 7 the figures were 99 percent against 1 percent, on day 14, 99 against 18, and by day 28, 100 percent of both ¹. PSA fell by 64 percent two weeks after the first dose, 85 percent after one month and 95 percent after three months, and stayed suppressed through the year ¹. The paper found the median PSA at days 14 and 28 significantly lower on degarelix than on leuprolide ³. P, the chance of a difference this large arising by luck, was below 0.001 ³.

The label adds two cautions ¹. The PSA results "should be interpreted with caution because of the heterogeneity of the patient population studied," and "no evidence has shown that the rapidity of PSA decline is related to a clinical benefit" ¹. The trial's endpoints were testosterone and PSA. The label reports no survival or tumor outcome from it ¹.

Studied for heart safety: PRONOUNCE, registered as NCT02663908, enrolled 545 men with prostate cancer and established atherosclerotic cardiovascular disease ⁴. That meant a past heart attack, an artery procedure, a documented narrowing above 50 percent or peripheral artery disease ⁴. From May 2016 to April 2020, at 113 sites in 12 countries, they were randomized one to one to degarelix or leuprolide for 12 months ⁴. The primary outcome was the time to a first major adverse cardiovascular event: death from any cause, heart attack or stroke ⁴. An independent committee that did not know the treatment judged each event ⁴.

Enrollment was stopped at 545 of the 900 planned because recruitment was slow and events were fewer than projected ⁴. The result did not settle the question. A major adverse cardiovascular event occurred in 15 men on degarelix, 5.5 percent, and 11 on leuprolide, 4.1 percent ⁴. The hazard ratio, the relative rate of events on degarelix against leuprolide, was 1.28, with a 95 percent confidence interval of 0.59 to 2.79 and P = 0.53 ⁴. An interval that wide, reaching from a lower rate to a higher one, means the trial could not tell the two drugs apart ⁴.

A sensitivity analysis counted investigator-reported cardiac events instead, by the broader definition used in the HERO trial of another GnRH antagonist ⁴. It found 14 on degarelix and 20 on leuprolide, a hazard ratio of 0.67 with an interval of 0.34 to 1.32, also not significant ⁴. The authors observed "no difference in MACE," major cardiovascular events, "at 1 year" and wrote that "the relative cardiovascular safety of GnRH antagonists and agonists remains unresolved" ⁴. The trial was sponsored and funded by Ferring Pharmaceuticals, the maker of Firmagon ⁴.

On the cancer side, PRONOUNCE found the two drugs alike. Castrate testosterone at day 28 was reached by 96.6 percent on degarelix and 96.5 percent on leuprolide, and sustained to day 336 in 93.6 and 94.8 percent ⁴. Testosterone below 20 ng/dL through day 336 was more common on degarelix, 80 percent against 67.8 ⁴. Disease progression occurred in 24 men on degarelix and 27 on leuprolide, a hazard ratio of 0.89 with an interval of 0.51 to 1.54 ⁴.

The label reports one single-dose study of drug levels in liver impairment, in 16 patients without prostate cancer ¹. Otherwise the label and the two trials report no trial of degarelix in healthy men, in women, or for any use outside prostate cancer, as of November 10, 2026 ³, ¹, ⁴.

What are the side effects?

Injection site reactions and hot flashes lead, and the label lists them beside leuprolide's figures ¹. In the pivotal trial, 79 percent of 207 men on degarelix and 78 percent of 201 on leuprolide reported an adverse reaction ¹. Most were grade 1 or 2, the label's lower severity grades, with grade 3 or 4 reactions in 1 percent or less ¹. Injection site reactions were reported by 35 percent on degarelix against under 1 percent on leuprolide, which is injected into a muscle ¹.

Hot flashes were reported by 26 percent against 21, and weight increase by 9 percent against 12 ¹. Rises in liver enzymes, the transaminases and GGT, were reported by 10 percent against 5 ¹. Hypertension was reported by 6 percent against 4, and chills by 5 percent against none ¹. Back pain was reported by 6 percent against 8, and joint pain (arthralgia) and urinary tract infection by 5 percent each against 9 ¹.

At the injection site the most frequent reactions were pain in 28 percent, redness in 17, swelling in 6, hardening (induration) in 4 and a nodule in 3 ¹. The label calls them "mostly transient, of mild to moderate intensity," occurring "primarily with the starting dose," and says they led to discontinuation in under 1 percent ¹. Erectile dysfunction, shrinking of the testes, breast enlargement, sweating and diarrhea were each reported by 1 percent or more in any study ¹. The paper on the same trial reported no systemic allergic reactions ³.

The longer record comes from an extension study of 385 men who finished the pivotal trial ¹. They were treated for a median of about 43 months, with a range of 1 to 58 ¹. The most common reactions were injection site reactions, fever, hot flashes, weight loss or gain, fatigue and raised liver enzymes ¹. One percent had injection site infections, including abscess ¹. Grade 1 or 2 rises in liver transaminases occurred in 47 percent and grade 3 rises in 1 percent ¹.

After one year of treatment, 10 percent of men had formed antibodies against degarelix ¹. The label says there is "no indication" that these affect its efficacy or safety ¹. In PRONOUNCE, injection site reactions were reported by 60.4 percent on degarelix against 26.8 on leuprolide ⁴. Fatigue was reported by 18.2 percent against 12.6, and hot flashes by 38.9 percent against 44.6 ⁴. Severe adverse events, 21.5 percent against 20.4, and discontinuations for adverse events, 4.7 percent against 4.1, were similar ⁴.

The warnings are the label's. It warns of hypersensitivity, allergic reactions: "anaphylaxis, urticaria and angioedema," hives and deep swelling, "have been reported" after marketing ¹. The drug "is contraindicated in patients with history of severe hypersensitivity to degarelix or to any of the product components" ¹. It warns that "androgen deprivation therapy may prolong the QT interval," a change in the heart's electrical timing ¹. It asks prescribers to weigh that risk in congenital long QT syndrome, congestive heart failure, frequent electrolyte abnormalities and with other QT-prolonging drugs ¹.

In the pivotal trial, three men in the two degarelix arms together, under 1 percent, had a corrected QT measure (QTcF) of 500 milliseconds or more ¹. Four men on leuprolide, 2 percent, did ¹. The label carries no warning on heart attack or stroke ¹. The PRONOUNCE authors note that FDA in 2010 required makers of GnRH agonists to add "the potential increased risk" of atherosclerotic cardiovascular disease to their safety information ⁴.

The label warns that Firmagon "can cause fetal harm and loss of pregnancy when administered to a pregnant woman," on animal findings ¹. It also warns that the drug "may impair fertility in males and females of reproductive potential" ¹. It says diagnostic tests of pituitary and testicular function "may be affected" during and after treatment ¹. It advises caution in men with a creatinine clearance under 50 mL/min, a measure of kidney function, and in severe liver disease ¹. Data are limited in the first group and the second was not studied ¹.

The label adds, from reports after marketing, that decreased bone density "can be anticipated" after long periods of medical castration ¹. That loss has been reported in men after surgical castration or GnRH agonist treatment ¹. Its counseling section lists hot flashes, flushing of the skin, increased weight, decreased sex drive and difficulties with erectile function as effects of androgen deprivation ¹. Of the men in its clinical studies, 82 percent were 65 or older and 42 percent were 75 or older ¹. The label saw no overall difference in safety or effectiveness from younger men ¹.

In sport

Degarelix is not named on WADA's 2026 Prohibited List ⁶. WADA, the World Anti-Doping Agency, names GnRH itself and "its agonist analogues (e.g. buserelin, deslorelin, goserelin, histrelin, leuprorelin, nafarelin and triptorelin)" in section S2.2.1 ⁶. That section, "Testosterone-stimulating peptides in males," is prohibited at all times ⁶.

Degarelix is an antagonist, and its label describes testosterone suppression, not stimulation ¹. Section S2 opens: "the following substances, and other substances with similar chemical structure or similar biological effect(s), are prohibited" ⁶.

What JumpstartMD offers

JumpstartMD does not prescribe degarelix. Our peptide library covers it so you have the facts on its FDA status and the evidence, current as of November 10, 2026.

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Compounded medications are not FDA-approved, and FDA does not review their safety, effectiveness, or quality before they are marketed. A licensed clinician decides after an evaluation whether a peptide is appropriate for you, and not every patient will qualify.