Teverelix
A long-acting GnRH-blocking decapeptide, first called Antarelix, now in late trials for prostate cancer and an enlarged prostate
Teverelix is a synthetic ten-amino-acid peptide that blocks the pituitary's receptor for gonadotropin-releasing hormone (GnRH), so testosterone falls within a day or two, without the initial surge that GnRH agonists cause. Developed in the early 1990s under the name Antarelix and used for years as a research tool in farm animals, it has since been tested in about 20 years of human studies. Phase 2 trials in advanced prostate cancer reached castration levels quickly but did not always hold them, and a placebo-controlled trial in benign prostatic hyperplasia improved urinary symptoms. It is not approved in any country.
Used in human trials: 180 mg SC + 180 mg IM, then 180 mg SC, Loading dose at one visit, then every 6 weeks, Subcutaneous and intramuscular (Phase 2 (2024): advanced prostate cancer, higher arm) Details ↓
Recommended Dosing
Used in human trials
No manufacturer dose exists for this use: these are amounts given in published trials, not recommendations.
Work out syringe units → · New to syringes? · All dosing data ↓
What is it?
Teverelix belongs to the GnRH antagonists, the same family as degarelix, cetrorelix and abarelix. GnRH is the hypothalamic signal that tells the pituitary to release luteinising hormone (LH) and follicle-stimulating hormone (FSH), which in turn drive testosterone in men and oestradiol in women. An antagonist sits on the pituitary receptor and blocks it, so LH and testosterone fall at once. Agonists such as leuprolide reach the same low testosterone only after a first surge, which matters in advanced prostate cancer, where a surge can briefly worsen symptoms.
The peptide was described in 1993 as Antarelix (code EP 24332), a water-soluble antagonist picked for its potency, its fairly low tendency to release histamine and its solubility. Under that name it became a common laboratory tool in animal reproduction: researchers used it to switch off LH in rams, stallions, mares, goats and pigs in order to study the reproductive axis or to time ovulation. Those studies show what the molecule does to the hormone cascade in mammals but are not evidence about treating people.
The first study in people, published in 2000, gave single small injections of 0.5 to 5 mg to healthy men. LH and testosterone dropped sharply within hours and recovered within days, longer at higher doses, and the terminal half-life was 24 to 75 hours. A 2003 study in nine healthy women found that a single 2.5 mg dose suppressed LH, FSH and oestradiol for about two days, with LH then rising above its starting level by day four. To make a drug that lasts weeks rather than days, developers moved to much larger doses of the trifluoroacetate salt, which forms a depot under the skin or in muscle and is released slowly. A 2026 biophysical study showed that the peptide assembles into amyloid-like fibrils, which is thought to explain that slow release.
The prostate cancer programme has run through several phase 2 designs. Five small loading-dose studies published in 2023 found that injections of 90 or 180 mg under the skin on three consecutive days brought more than 90% of men below the castration threshold by day 28. A 2024 open-label trial of 50 men tried a single-visit loading dose split between skin and muscle, then a maintenance dose every six weeks: the higher dose reached the target at day 28 but castration rates slipped by day 42, and the authors concluded the regimen did not hold castration well enough. A modelling study then picked a larger regimen for a planned phase 3 trial that will also compare heart safety with a GnRH agonist.
In men with benign prostatic hyperplasia, a 2025 placebo-controlled phase 2 trial in 81 men found that two 60 mg injections lowered urinary symptom scores by about a third by week 16 against about 5% with placebo, shrank the prostate by about 11% and improved urine flow. The commonest side effects across the trials were injection-site reactions and, as with any drug that lowers testosterone, hot flushes. Teverelix has no approval from the FDA, the EMA or any other regulator, and anything sold under its name outside a trial is not the clinical product.
Mechanism of Action
Teverelix competes with natural GnRH at the pituitary receptor and blocks it, so the hormones further down the chain fall without the surge that agonists produce.
Blocks the pituitary GnRH receptor
Binding competitively and reversibly, it stops GnRH from triggering LH and FSH release (PMID 34448368).
Testosterone or oestradiol falls
With LH gone, the testes make little testosterone and the ovaries little oestradiol, within hours in healthy volunteers (PMIDs 10872648, 14510918).
A depot sets the duration
Large doses of the salt gel and fibrillate at the injection site and leak out slowly, so each dose lasts weeks (PMIDs 34448368, 41411501).
Published Research
These are the studies of teverelix read from their PubMed abstracts on October 29, 2026: seven in people (healthy volunteers, prostate cancer, benign prostatic hyperplasia and a population model), eight in animals under its older name Antarelix or its current one, and four laboratory studies. Animal papers that describe only 'a GnRH antagonist' without naming the compound are not carded.
First doses in healthy men
Single injections under the skin of 0.5 to 5 mg, against placebo, in healthy men. LH fell by up to 93% and testosterone by up to 93%, FSH less; after 5 mg, testosterone stayed under 1 ng/mL for a median of 33 hours. Peak levels came 1 to 4 hours after dosing, terminal half-lives ran 24 to 75 hours, and the main side effects were brief, mild injection-site reactions.
One dose in nine healthy women
A single 2.5 mg injection in the early follicular phase cut LH from 6 hours, lowest at 8 hours, with recovery by 72 hours; FSH and oestradiol fell for a day or two. Detailed sampling showed it reduced the size of LH pulses, not their frequency. By 96 hours LH was above its starting level.
Phase 1 in older healthy men
An open-label single-dose study. Drug entered the blood in two phases, a quick release followed by a slow one from a depot, and the pattern differed between skin and muscle. Exposure rose roughly in proportion to dose from 60 to 120 mg under the skin, and 90 mg into muscle suppressed LH, FSH and testosterone for longer than 90 mg under the skin.
Five loading-dose studies in prostate cancer
Five single-arm phase 2 studies treated 82 men with advanced hormone-sensitive prostate cancer. Daily injections under the skin of 90 mg or 180 mg on three days in a row kept testosterone at castration level for a mean of about 55 and 69 days, with over 90% castrated at day 28. Onset took 1 to 2 days under the skin and longer by muscle; injection-site reactions were the commonest side effect.
Phase 2: castration reached, not held
Fifty men received a loading dose split between skin and muscle at one visit, then a dose under the skin every six weeks. At the higher dose 97.5% reached castration by day 28, against 62.5% at the lower dose, but by day 42 the rates were 82.5% and 50%. Injection-site hardening (80%), redness (70%) and hot flushes (42%) were the commonest events, and the authors judged castration inadequately maintained.
Benign prostatic hyperplasia, placebo-controlled
Eighty-one men over 50 with moderate to severe urinary symptoms were randomised to two injections of 60 mg (days 1 and 3) or placebo. At week 16 the symptom score fell by 6.3 points against 1.1, prostate volume fell by 11% within four weeks, and urine flow and quality of life improved. The authors see a possible role in preventing repeat urinary retention, still to be tested.
Modelling the phase 3 dose
Pooling data from nine phase 2 studies in 229 patients, a population model described absorption by both routes and the testosterone response. Simulations chose a larger loading dose by both routes and a six-weekly maintenance dose for phase 3, predicted to keep at least 95% of men castrated to 52 weeks; that trial will compare heart safety with a GnRH agonist.
Introduced as Antarelix (EP 24332)
The developers describe a new water-soluble GnRH antagonist with the sequence Ac-D-Nal, D-Cpa, D-Pal, Ser, Tyr, D-Hci, Leu, Lys(iPr), Pro, D-Ala-NH2, report its activity in cells and several animal models, and select it for development for its potency, modest histamine release and solubility.
Measuring it in blood; dogs
A radioimmunoassay was built to measure Antarelix (teverelix) in plasma at femtomole levels, with little cross-reaction with natural GnRH or other analogues except one, and was used to describe its pharmacokinetics in dogs given 10 micrograms per kg into a vein or under the skin.
A switch for the reproductive axis in rams
A single 500 microgram intravenous dose abolished LH pulses within about 20 minutes and testosterone pulses within about 80 minutes in mature rams, a reversible chemical castration; GnRH pulses in the cerebrospinal fluid then became more frequent as the brain sensed the loss of testosterone.
Stallions: hormones, libido and testes
In four pony stallions, LH, FSH, testosterone and oestradiol fell within 48 hours and stayed low for four weeks. Sperm counts and motility held, but recovery time between erections lengthened, and testes removed eight weeks later showed degeneration; reversibility was not established.
Delaying ovulation in mares
Given twice daily for eight days, Antarelix postponed ovulation in all five treated mares to about 19 days, against 6 days in controls, and suppressed LH more strongly than the same dose of cetrorelix, which delayed ovulation in two of five. FSH was unchanged with either drug.
Daily doses in goats
Five goats received 0.5 mg of teverelix daily for 11 days. FSH and LH fell, large and medium follicles disappeared and inhibin A dropped, while small follicles increased, a way of pooling follicles before stimulation.
Goats after stopping
After six days of Antarelix, LH in goats returned to control levels within three days of the last injection, but small follicles kept accumulating and follicle function was still altered, which may explain the poor embryo quality seen when stimulation followed soon after.
Gilts: LH down, FSH unchanged
Twice-daily intravenous injections for four days cut the LH released by cycling gilts about fourfold without changing FSH or the pre-ovulatory oestradiol rise; with LH suppressed, the progesterone normally made after ovulation failed to appear.
Compared with cetrorelix and ganirelix in cells
In human cell lines carrying the GnRH receptor and in mouse pituitary cells, teverelix blocked GnRH-triggered calcium signalling at 100 nM to 1 µM, less potently than cetrorelix. All three antagonists inhibited downstream kinase signalling and LH-beta gene activation at similar doses.
Why the depot lasts: amyloid-like fibrils
At injection concentrations the trifluoroacetate salt is a microcrystalline suspension, and at low concentrations it forms amyloid-like fibrils, confirmed by X-ray diffraction and electron microscopy. Fibril formation was fast and depended on pH and on the trifluoroacetate content.
Slow-release microspheres
Teverelix was encapsulated in microspheres made from polymers of lactic-glycolic acid with polyethylene glycol, with encapsulation yields above 80%; the PEG-containing polymers released the peptide faster in the laboratory than plain lactic-glycolic acid spheres.
Measuring its tendency to aggregate
A fluorescence method was developed to find the concentration at which cetrorelix, teverelix and ozarelix, three antagonists containing naphthylalanine, begin to aggregate, compared with a GnRH analogue that does not aggregate.
Dosing Data
Teverelix has no approved label anywhere. The rows below are the regimens given in published human trials, from the trial abstracts; none is a recommendation, and the prostate cancer regimen is still being revised.
Educational information, not medical advice. Each dose above is tagged with its source: an approved label, a published human study, animal data, or amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.
What a Buyer Needs to Know
What is sold, how it is mixed, stored and taken, and what is known about its safety, quality and legal status. Each part names its source. Where we have none, it says unknown.
What is sold
Unknown: we hold no label and no published test that says what forms or vial sizes Teverelix is sold in. A vial's own label is a seller's claim, not a source.
Mixing a vial: a worked example
An arithmetic example, not a recommendation: a 10 mg vial mixed with 3 mL of bacteriostatic water holds 3,333.3 mcg per mL, so 180 mg, the first amount in the “Phase 2 (2024): advanced prostate cancer, higher arm” row (180 mg SC + 180 mg IM, then 180 mg SC) would be 5400.0 units, more than a 1 mL U-100 syringe holds. Put your own vial's numbers into the reconstitution calculator.
Source: dose: Used in human trials, PMID 38311868 (Dosing Data below); vial and water: the calculator's default example, not a vial size we have a source for.
Storage before and after mixing
Unknown: no label or published stability study on file says how to store Teverelix, before or after mixing. The mixing guide sets out the general rules, with their sources: keep a mixed vial in the fridge, and use it promptly, as the bacteriostatic water label says of any drug dissolved in it. The 28 days often quoted is the limit for an opened multiple-dose vial from a manufacturer, an outer limit set for sterility, not a time a mixed solution has been shown to keep. Nobody has published how long Teverelix stays intact once mixed.
How it is taken
As it was given in human studies: Subcutaneous and intramuscular (Loading dose at one visit, then every 6 weeks; Phase 2 (2024): advanced prostate cancer, higher arm); Subcutaneous (Once daily on 3 consecutive days; Phase 2 loading studies (2023): prostate cancer).
For injection technique, sites and needle disposal, see the mixing guide.
Source: Used in human trials: the route and frequency of each row in Dosing Data below.
What to expect, and when
How long it stays in the body: a half-life of 24-75 hours after single 0.5-5 mg doses; depot release from large doses. After about five half-lives almost none is left.
How long the doses were given: Phase 2 (2024): advanced prostate cancer, higher arm: To day 168; Phase 2 loading studies (2023): prostate cancer: Single loading course; Phase 2 (2025): benign prostatic hyperplasia: Two injections; followed to week 16.
When effects appear: unknown; no source on this page gives a time to effect for Teverelix. Results reported in the studies are under Published Research.
Source: half-life: PMID 10872648; Used in human trials, the duration of each row in Dosing Data below.
Side effects, and when to stop or get help
From the Side Effects section: Injection-site reactions were the most common event in every trial: hardening in 80% and redness in 70% in the 2024 phase 2 trial, mostly grade 1; Hot flushes in 42% of men in the 2024 prostate cancer trial, an expected effect of low testosterone; No adverse events of severe intensity in the five loading-dose studies (2023); Small single doses in healthy men caused only brief, mild injection-site reactions (2000); In stallions, testes showed degeneration eight weeks after treatment; whether that reverses was not shown. Full list and cautions ↓
When to stop or get help: unknown; no label or trial on file sets rules for stopping Teverelix. Treat a severe or unexpected reaction as a reason to stop and see a doctor.
Source: the Side Effects section below (“From the human trials read”).
Interactions
Unknown: a PubMed search for human interaction studies of Teverelix (reviewed 2026-10-28) found none. Unknown is not the same as safe to combine.
Every peptide's record, with its source: the interaction matrix.
Checking what you bought
Unknown: no published independent test of Teverelix products is in our lab-results database yet, so how products sold under this name measure up is not known.
To read a certificate of analysis, paste it into the COA decoder; it checks the measured mass against Teverelix's expected mass, 1,459.1 Da, from this entry's molecular data. Trust & Verification explains what independent testing can and cannot show.
Legal status
US: In Clinical Trials (Not approved anywhere). Sport: Prohibited (S0 catch-all).
Country by country ↓ · Regulatory tracker
Source: this entry's approval status and the WADA Prohibited List, as in Legal Status below.
Side Effects & Contraindications
Reported Side Effects
From the human trials read.
Contraindications & Cautions
No product label exists. These cautions follow from how the drug works and from the trials.
Legal Status
Teverelix is an investigational drug with no marketing approval anywhere.
Frequently Asked Questions
?What is teverelix?
A synthetic ten-amino-acid GnRH antagonist. It blocks the pituitary receptor that drives LH and FSH, so testosterone in men and oestradiol in women fall within hours, without the initial surge that GnRH agonists cause.
?Is teverelix the same as Antarelix?
Yes. Antarelix, code EP 24332, was its name in the 1990s, when it was introduced and used widely in animal reproduction research; PubChem lists EP 24332 among teverelix's synonyms and a 1996 paper writes 'Antarelix (teverelix)'.
?Is it approved for prostate cancer?
No. Phase 2 trials reached castration levels quickly, but the 2024 trial found its regimen did not hold them well enough, and a larger regimen was chosen for phase 3. Approved GnRH antagonists include degarelix and, as a tablet, relugolix.
?What did the BPH trial find?
In 81 men with an enlarged prostate, two 60 mg injections lowered urinary symptom scores by about a third by week 16, against about 5% with placebo, and shrank the prostate by about 11% (2025).
?What are the side effects?
Mostly injection-site hardening and redness, and hot flushes from low testosterone. Longer suppression would bring the effects common to all androgen deprivation, which the trials so far were too short to measure.
References
- [clinical-trial] Erb K, et al. "Pituitary and gonadal endocrine effects and pharmacokinetics of the novel luteinizing hormone-releasing hormone antagonist teverelix in healthy men--a first-dose-in-humans study." Clin Pharmacol Ther, 2000;67(6):660-9. PMID: 10872648.
- [clinical-trial] Gianotti L, et al. "Suppression and recovery of LH secretion by a potent and selective GnRH-receptor antagonist peptide in healthy early follicular-phase women are mediated via selective control of LH secretory burst mass." Clin Endocrinol (Oxf), 2003;59(4):526-32. PMID: 14510918.
- [clinical-trial] MacLean CM, et al. "Pharmacokinetic, Safety, and Pharmacodynamic Properties of Teverelix Trifluoroacetate, a Novel Gonadotropin-Releasing Hormone Antagonist, in Healthy Adult Subjects." Clin Pharmacol Drug Dev, 2022;11(2):257-269. PMID: 34448368.
- [clinical-trial] MacLean CM, et al. "Safety, Pharmacokinetic and Pharmacodynamic Evaluation of Teverelix for the Treatment of Hormone-Sensitive Advanced Prostate Cancer: Phase 2 Loading-Dose-Finding Studies." Medicina (Kaunas), 2023;59(4). PMID: 37109639.
- [clinical-trial] Ulys A, et al. "Efficacy, tolerability, and safety of teverelix DP in patients with advanced prostate cancer: A multicenter, open-label, phase 2 trial." Prostate, 2024;84(6):584-598. PMID: 38311868.
- [clinical-trial] Ulys A, et al. "Teverelix is a potential treatment option for the prevention of acute urinary retention recurrence in men suffering from benign prostatic hyperplasia." Int Urol Nephrol, 2025;57(2):427-433. PMID: 39428443.
- [pubmed] Sannala CKR, et al. "A Model-Informed Drug Development Approach to Design a Phase 3 Trial of Teverelix Drug Product in Advanced Prostate Cancer Patients with Increased Cardiovascular Risk." Clin Pharmacol Drug Dev, 2024;13(8):915-929. PMID: 38757461.
- [pubmed] Deghenghi R, et al. "Antarelix (EP 24332) a novel water soluble LHRH antagonist." Biomed Pharmacother, 1993;47(2-3):107-10. PMID: 7693007.
- [pubmed] Sorensen S, et al. "Radioimmunoassay of Antarelix, a luteinizing hormone releasing-hormone antagonist, in plasma and its application for pharmacokinetic study in dogs." J Immunoassay, 1996;17(3):205-26. PMID: 8842981.
- [pubmed] Blache D, et al. "GnRH secretion into CSF in rams treated with a GnRH antagonist." J Neuroendocrinol, 1997;9(12):887-92. PMID: 9468013.
- [pubmed] Hinojosa AM, et al. "The effect of a GnRH antagonist on endocrine and seminal parameters in stallions." Theriogenology, 2001;56(5):903-12. PMID: 11665891.
- [pubmed] Guillaume D, et al. "Comparison of the effects of two GnRH antagonists on LH and FSH secretion, follicular growth and ovulation in the mare." Reprod Nutr Dev, 2002;42(3):251-64. PMID: 12405453.
- [pubmed] Gonzalez-Bulnes A, et al. "Effect of GnRH antagonists treatment on gonadotrophin secretion, follicular development and inhibin A secretion in goats." Theriogenology, 2004;61(5):977-85. PMID: 14757481.
- [pubmed] Gonzalez-Bulnes A, et al. "Restoration of endocrine and ovarian function after stopping GnRH antagonist treatment in goats." Theriogenology, 2005;63(1):83-91. PMID: 15589275.
- [pubmed] Brüssow KP, et al. "Alteration of gonadotrophin and steroid hormone release, and of ovarian function by a GnRH antagonist in gilts." Anim Reprod Sci, 2001;66(1-2):117-28. PMID: 11343847.
- [pubmed] Sperduti S, et al. "GnRH Antagonists Produce Differential Modulation of the Signaling Pathways Mediated by GnRH Receptors." Int J Mol Sci, 2019;20(22). PMID: 31703269.
- [pubmed] Li X, et al. "Mechanism of Self-Assembly of the Gonadropin Releasing Hormone Antagonist Teverelix into Amyloid Fibrils." Mol Pharm, 2026;23(1):164-176. PMID: 41411501.
- [pubmed] Mallardé D, et al. "PLGA-PEG microspheres of teverelix: influence of polymer type on microsphere characteristics and on teverelix in vitro release." Int J Pharm, 2003;261(1-2):69-80. PMID: 12878396.
- [pubmed] Schneider A, et al. "Fluorescence spectroscopic determination of the critical aggregation concentration of the GnRH antagonists Cetrorelix, Teverelix and Ozarelix." J Fluoresc, 2010;20(6):1233-40. PMID: 20514551.
- [other] PubChem CID 16135076, Teverelix: formula C74H100ClN15O14, molecular weight 1459.1. Read October 28, 2026. https://pubchem.ncbi.nlm.nih.gov/compound/16135076
Sources & Citations
Studies were read from their PubMed records on October 29, 2026. The sequence and synonyms come from PubChem CID 16135076; status from Drugs@FDA (openFDA) and the EMA medicines list, read October 28, 2026. Grey Peptides sells nothing and links to no vendor.
Medical Disclaimer: This content is for educational and informational purposes only. It is not medical advice, and nothing here is an instruction to obtain or use any compound. Talk to a licensed clinician about your own situation.