Triptorelin (Gonapeptyl, Pamorelin): uses, research, side effects and status in Finland

In short

Triptorelin is a long-acting synthetic analogue of the hormone GnRH with a marketing authorisation in Finland (Gonapeptyl and Pamorelin) [2]regulator. In continued use it shuts down sex hormone production, and its efficacy in prostate cancer and as add-on breast cancer treatment rests on large randomised trials [4]official [12]A.

• In men triptorelin first raises testosterone, but in continued use it pushes it down. In prostate cancer patients testosterone fell to castrate levels within 2-3 weeks [4]official.
• Best evidence: in breast cancer trials of 4,690 women, ovarian function was suppressed mainly with triptorelin [4]official, and exemestane with it reduced recurrences more than tamoxifen with it [12]A.
• Weakness: bone density falls, hot flushes are common, the risk of depression rises, and use carries metabolic and heart risks [4]official.
• In Finland triptorelin is on the medicines list and has two authorised products [1, 2]regulator. WADA bans it in men at all times [25]regulator.

What is triptorelin?

Triptorelin is a ten-amino-acid peptide, a synthetic analogue of gonadotropin-releasing hormone (GnRH). At first it speeds up the pituitary's release of the hormones LH and FSH, but given continuously it suppresses it [4]official. Depot products are injections from which the active substance is released gradually [4]official.

Triptorelin is authorised widely in Europe. The EMA Article 57 data (as of 9 Oct 2026) listed triptorelin products in 28 countries, and two for Finland [2]regulator:

• Gonapeptyl (triptorelin): a product given under the skin, marketing authorisation holder Ferring Lääkkeet Oy [2]regulator.
• Pamorelin (triptorelin): a product given into a muscle and a product given into a muscle or under the skin, marketing authorisation holder Ipsen [2]regulator.

Triptorelin has no central EU marketing authorisation as a human medicine; the only triptorelin product among EMA's centrally authorised medicines is the veterinary medicine OvuGel [3]regulator. The official information on this page comes from UK and US product texts, and the indications of the Finnish products may differ from them. In the UK, Decapeptyl SR (triptorelin) and Gonapeptyl Depot (triptorelin) are prescription-only medicines [4, 5]official. Basics: What are peptides?. All substances: Peptides A-Z.

Evidence at a glance

Each cell gives the kind of study and the source. The letter is the level of evidence, not the result.

"-" = no such study is known. For an approved medicine the evidence comes mainly from human studies; the animal column is from the preclinical part of the Summary of Product Characteristics.

What is triptorelin used for?

Triptorelin is used when sex hormone production needs to be pushed down: in prostate cancer, as add-on treatment of breast cancer, in endometriosis, in uterine fibroids and in early puberty in children [4, 5, 7]official.

• Prostate cancer: locally advanced and metastatic cancer, and treatment given with radiotherapy or surgery in high-risk disease [4]official. In the US, Trelstar (triptorelin) is approved for advanced prostate cancer [6]official.
• Breast cancer: add-on treatment of hormone-receptor-positive early breast cancer together with tamoxifen or an aromatase inhibitor, in women at high risk of recurrence who are still premenopausal after chemotherapy [4]official.
• Endometriosis and uterine fibroids: for fibroids before surgery or when surgery is not suitable [4]official.
• Early puberty: the indication of the UK Gonapeptyl Depot is puberty starting before age 9 in girls and before age 10 in boys [5]official; the US Triptodur (triptorelin) is for children aged 2 and over [7]official.
• Fertility treatment (research evidence): GnRH agonists, the group triptorelin belongs to, have been used for final egg maturation in IVF [17]A.
• Protecting the ovaries (research use): given during chemotherapy to prevent early menopause [14, 16]A.

How does triptorelin work?

Triptorelin is a GnRH analogue that acts on the pituitary. In the first days the release of LH and FSH speeds up, and in men testosterone and dihydrotestosterone rise. When dosing continues for more than a week, gonadotropin release is suppressed and testosterone falls. In prostate cancer patients testosterone fell to castrate levels within 2-3 weeks [4]official.

In women continued use suppresses the ovaries' oestrogen production. According to the Summary of Product Characteristics the effect is reached 3-4 weeks after administration [4]official. The initial hormone peak explains why prostate cancer symptoms can briefly worsen at the start of treatment [4]official.

Has triptorelin been studied in humans?

Yes, extensively. There are large randomised trials in prostate cancer and breast cancer, and smaller ones for the other indications [4]official [8, 12]A.

Prostate cancer

• Compared with removal of the testes. According to the Summary of Product Characteristics, in three long controlled studies triptorelin lowered testosterone as quickly as surgical removal of the testes and was as effective in the long term. In the six- and eight-year analyses there was no difference in survival [4]official.
• Short or long treatment. In a trial of 970 men, six months of hormone treatment with radiotherapy was inferior to three years: five-year mortality was 19.0% and 15.2%. The treatment was triptorelin or goserelin [4]official.
• Compared with leuprorelin (2003). In a trial of 284 men, triptorelin lowered testosterone more slowly in the first month (91.2% vs 99.3% at castrate level), but from the second month the result was the same, and castration was maintained equally well for nine months [8]A.
• Compared with leuprorelin (1997). In a trial of 67 men, at month two testosterone was below 1.0 nmol/l in 77% on triptorelin and 48% on leuprorelin [9]A.

Breast cancer

• SOFT (2015). In 3,066 women, adding ovarian suppression to tamoxifen did not significantly improve disease-free survival in the whole group (86.6% vs 84.7% at five years). According to the authors, it improved outcomes in women whose risk of recurrence was high enough to receive chemotherapy and who remained premenopausal afterwards [11]A.
• SOFT and TEXT combined (2014). In 4,690 women, exemestane with ovarian suppression reduced recurrences more than tamoxifen with ovarian suppression: disease-free at five years 91.1% and 87.3%. Overall survival did not differ. The ovaries were suppressed with triptorelin, removal of the ovaries or radiotherapy [12]A.
• Eight-year results (2018). With longer follow-up, adding ovarian suppression to tamoxifen in SOFT significantly improved both disease-free survival (83.2% vs 78.9%) and overall survival (93.3% vs 91.5%). With exemestane and ovarian suppression 85.9% were disease-free. Side effects were more common in the groups whose ovaries were suppressed [13]A.

Protecting the ovaries during chemotherapy

In the Italian PROMISE-GIM6 trial, 281 premenopausal breast cancer patients received chemotherapy alone or with triptorelin. After one year, early menopause occurred in 25.9% without triptorelin and 8.9% with triptorelin [14]A. A US trial was stopped after 49 patients because no difference seemed to emerge: periods returned in 90% and 88% [15]A. In a meta-analysis of seven trials, GnRH agonists were linked with more frequent return of periods, but the evidence was not enough to assess fertility [16]A.

Fertility treatment

In a Cochrane review, 17 randomised trials (1,847 women) compared a GnRH agonist with hCG for final egg maturation. In fresh embryo transfer the GnRH agonist reduced ovarian hyperstimulation syndrome, but also the live birth rate: if the chance with hCG was 31%, with the agonist it was 12-24% [17]A. The review covered GnRH agonists as a group, not triptorelin alone.

Early puberty and endometriosis

In a study of 44 children without a comparison group, triptorelin given every six months kept LH at the pre-pubertal level in 93.2% at six months, and no unexpected side effects were reported [18]B. As a diagnostic test, triptorelin raised LH in girls less and more slowly than the standard GnRH test [22]B.

In treatment after endometriosis surgery, a dienogest tablet was as effective as a triptorelin injection in a randomised trial (142 women enrolled, 120 analysed) [19]A. In uterine fibroids 90-100% of women stopped bleeding within two months, and the fibroids shrank [4]official.

Who studies triptorelin?

Triptorelin is studied by cancer and reproductive medicine research groups. Examples are the SOFT and TEXT breast cancer trials [11, 12]A, the Italian PROMISE-GIM6 group at 16 hospitals [14]A, the South African Triptorelin Study Group [8]A and the US Children's Oncology Group, whose trial is under way [23]E, not peer-reviewed. Thailand's National Doping Control Center has developed a method to find triptorelin in urine [21]B.

Author of this page: editorial team

This page was written by the Molecular Recovery editorial team. The draft was made with the help of AI, and the claims were checked against the sources (AI policy). The page has not been medically reviewed. How we work: About us.

How long does triptorelin stay in the body?

The substance itself is cleared within hours, but a depot product releases it over weeks. The half-life of a solution given under the skin was about 7.6 hours in healthy volunteers and 11.7 hours on average in prostate cancer patients, but it varied between patients [4]official.

From a depot product injected into a muscle, the substance on the surface is released first and the rest fairly evenly after that. In women with endometriosis or fibroids the peak level was reached in 2-6 hours, and the substance did not accumulate with monthly injections over six months [4]official.

What are the side effects of triptorelin?

Most side effects come from what the medicine does: the lack of sex hormones. According to the Summary of Product Characteristics, most of them are also known after surgical castration [4]official.

Men

• Most common: hot flushes and lower sexual desire [4]official.
• Start of treatment: the brief rise in testosterone can worsen prostate cancer symptoms in up to 5% of patients, usually as urinary symptoms or bone pain. Isolated cases of spinal cord compression and urinary tract obstruction have been reported [4]official.
• Long treatment: bone loss, osteoporosis and fracture risk, anaemia, QT prolongation, and metabolic changes such as impaired glucose tolerance and fatty liver. In epidemiological data the risk of cardiovascular disease is raised, but prospective data have not confirmed a link with cardiovascular death [4]official.

Women

• Most common (at least one in ten): headache, lower sexual desire, sleep problems, mood changes, pain during sex, period pain, genital bleeding, hot flushes, sweating, vaginal dryness and weakness [4]official.
• Bone: bone density falls by about 1% a month on average during a six-month treatment [4]official.
• Breast cancer combinations: osteoporosis was reported in 39% with exemestane and 25% with tamoxifen. High blood pressure was very common (23% and 22%), and depression occurred in about half, severe in under 5% [4]official. In the eight-year SOFT results, grade 3 or higher side effects occurred in 24.6% on tamoxifen, 31.0% on tamoxifen with ovarian suppression and 32.3% on exemestane with ovarian suppression [13]A.

All users

In users of GnRH agonists, depression, which can be severe, and convulsions have been reported. Rarely, treatment can reveal a pituitary tumour, which can bleed suddenly [4]official. More: Side effects and safety.

Animal studies

According to the Summary of Product Characteristics, long-term dosing caused benign pituitary tumours in almost all rats, but no tumours were seen in mice, and they have not been described in humans. Other animal findings, such as shrinking of the testes, were linked to the expected effect of the medicine and were largely reversible [4]official.

Interactions and who lacks data

According to the Summary of Product Characteristics, medicines that raise prolactin should not be used at the same time. Because hormone treatment can prolong the QT interval, use together with medicines that prolong the QT interval, such as certain antiarrhythmics, methadone, moxifloxacin and antipsychotics, must be carefully assessed [4]official.

Triptorelin is not used during pregnancy or breastfeeding, and non-hormonal contraception is needed during treatment. For endometriosis and fibroids it is not recommended under age 18. There are no specific data for people who already have osteoporosis [4]official.

What speaks against it and what is unknown

Triptorelin's efficacy in suppressing hormones is well established, but not every additional use has held up [11, 15, 17]A.

Counter-evidence

• The primary five-year result of SOFT was negative: adding ovarian suppression to tamoxifen did not significantly improve disease-free survival in the whole group [11]A. At eight years of follow-up the difference was significant [13]A.
• In ovarian protection, one randomised trial was stopped because no difference emerged [15]A.
• In fertility treatment, a GnRH agonist lowered live births in fresh embryo transfer compared with hCG [17]A.
• In endometriosis, a tablet (dienogest) was as effective as a triptorelin injection [19]A.
• In prostate cancer, one trial reported better nine-month survival with triptorelin than with leuprorelin [8]A, but according to a systematic review no comparative trial was large enough to assess survival [10].

What the evidence does not support

• "Triptorelin restores testosterone after anabolic steroids": the idea rests on a single case report in which one man's testosterone returned to normal within a month of one injection [20]B. No controlled studies have been published (as of October 2026). In continued use triptorelin lowers testosterone instead [4]official.
• "All GnRH agonists are the same": according to a review the fall in testosterone is similar, but there is not enough evidence of equivalence [10].

What is not known

• Whether GnRH agonists differ in survival: trials have not been large enough [10].
• Whether triptorelin protects fertility during chemotherapy: according to the meta-analysis the evidence is not enough [16]A.
• The effects of repeated use in healthy men: they have not been studied.

Triptorelin dosing in studies

Triptorelin is a prescription medicine at least in the UK [4, 5]official, so this site has no dose page or calculator for it. According to the UK Summary of Product Characteristics, the product is used only under the supervision of a specialist [5]official.

The study designs in brief, without doses: in the prostate cancer trial an injection was given into a muscle every four weeks, nine times [8]A. In the PROMISE trial the first injection was given at least one week before chemotherapy and then every four weeks during treatment [14]A. In the puberty study the children received two injections six months apart [18]B.

What the numbers cannot tell you. In the US product text the different strengths are meant for different dosing intervals, and they cannot be added together because they release differently [6]official. The designs are not treatment instructions. Research doses of other substances: Dosing.

Triptorelin vs leuprorelin and gonadorelin: what is the difference?

Leuprorelin is another GnRH agonist. In comparative trials they lowered testosterone and PSA to a similar degree, but the trials were small, and none was large enough to compare survival [10]. In one trial triptorelin lowered testosterone more slowly [8]A, in another more deeply [9]A.

Gonadorelin is a synthetic form of the body's own GnRH, triptorelin a long-acting analogue of it [22]B. In a puberty test in children, the standard GnRH test raised LH more, and in the triptorelin test the peak came later and stayed lower [22]B.

Combinations and blends

In treatment triptorelin is often combined with other medicines: in breast cancer with tamoxifen or an aromatase inhibitor [4]official [12]A, in prostate cancer with radiotherapy, and at the start of treatment an anti-androgen can be considered to blunt the initial rise in testosterone [4]official. In breast cancer triptorelin must be used without interruption alongside an aromatase inhibitor, so that oestrogens do not rise again [4]official. Triptorelin is not in any blend on this site.

Status in the United States

In the US, Trelstar (triptorelin) is approved for advanced prostate cancer and is given into a muscle under the supervision of a physician [6]official. Triptodur (triptorelin) is approved for central precocious puberty in children aged 2 and over, and may only be given by a healthcare provider [7]official.

Is triptorelin legal in Finland?

In Finland triptorelin is a medicine with two authorised products. It is named in annex 1 of Fimea's medicines list, and the substances in annex 1 are controlled as medicines [1]regulator.

• Marketing authorisation. The EMA Article 57 data listed the triptorelin products Gonapeptyl and Pamorelin for Finland (as of 9 Oct 2026) [2]regulator. The data show the authorisation, not whether the products are available in pharmacies.
• Prescription status. The sources of this page give no information on the Finnish prescription status. In the UK, triptorelin products are prescription-only medicines [4, 5]official.
• Doping offence law. Triptorelin is not named among the Criminal Code doping substances listed in Government Decree 705/2002 [27]regulator.
• Import. Ordering medicines from abroad is covered on Peptides and the law in Finland. Bringing them back from travel: Travelling with peptides.

This is not legal advice. Disclaimer.

Is triptorelin doping?

Yes, in men. On the WADA 2026 Prohibited List triptorelin is an example in class S2.2.1, testosterone-stimulating peptides in males (GnRH and its agonist analogues), and the substances in this class are prohibited at all times [25]regulator. The Finnish SUEK list names triptorelin under the same item [26]regulator.

In a study by a Thai doping control centre, a breakdown product of triptorelin was found in the urine and blood of five prostate cancer patients; according to the researchers it can show use even when the substance itself can no longer be found [21]B.

How is the quality of a triptorelin product judged?

The authorised triptorelin products in Finland are Gonapeptyl and Pamorelin [2]regulator. According to the Summary of Product Characteristics the depot product is a suspension of microparticles, which must not be injected into a blood vessel by mistake [4]official.

A certificate of analysis (COA) does not show that a product is safe. More: How to read a COA and check a test result.

The future: what comes next?

On 15 Oct 2026 the ClinicalTrials.gov registry listed, among others, these ongoing triptorelin trials:

• Protecting the ovaries in young cancer patients. A phase 3 trial by the Children's Oncology Group in the US, an estimated 60 participants, primary results estimated in October 2029 [23]E, not peer-reviewed.
• Breast cancer. A phase 2 trial by the Spanish SOLTI group of elacestrant with or without triptorelin, an estimated 96 participants, primary results estimated in December 2026 [24]E, not peer-reviewed.

FAQ

Read the research yourself: sources

Every source opens the original publication or the regulator's page. The level shows what the source itself reports.

1. Finland. Lääkeluettelo (Fimea medicines list), 230/2025, annex 1: "Triptoreliini". Finlex regulator
2. European Medicines Agency. Article 57 product data (EMA/518502/2018 Rev.90, data as of 9 Oct 2026): triptorelin entries in 28 countries; in Finland Gonapeptyl (triptorelin acetate, subcutaneous, Ferring Lääkkeet Oy) and Pamorelin (triptorelin, intramuscular and intramuscular or subcutaneous, Ipsen). EMA regulator
3. European Medicines Agency. Medicine data (centrally authorised medicines, data set of 14 Oct 2026): no human medicine with triptorelin; one veterinary medicine, OvuGel (triptorelin). EMA regulator
4. Ipsen Ltd. Decapeptyl SR 3 mg powder and solvent for suspension for injection (triptorelin): Summary of Product Characteristics (UK, prescription only medicine, text revised 1 Jun 2026). electronic medicines compendium (emc). emc official
5. Ferring Pharmaceuticals Ltd. Gonapeptyl Depot 3.75 mg powder and solvent for suspension for injection (triptorelin): Summary of Product Characteristics (UK, prescription only medicine, text revised 2 Dec 2024). electronic medicines compendium (emc). emc official
6. U.S. National Library of Medicine, DailyMed. TRELSTAR (triptorelin pamoate) label, Verity Pharmaceuticals (label version of 10 Jul 2026). DailyMed (NIH) official
7. U.S. National Library of Medicine, DailyMed. TRIPTODUR (triptorelin) label, Azurity Pharmaceuticals (label version of 29 Sep 2025). DailyMed (NIH) official
8. Heyns CF, Simonin MP, Grosgurin P, Schall R, Porchet HC; South African Triptorelin Study Group. Comparative efficacy of triptorelin pamoate and leuprolide acetate in men with advanced prostate cancer. BJU Int. 2003;92(3):226-231. PMID 12887472 A
9. Kuhn JM, Abourachid H, Brucher P, et al. A randomized comparison of the clinical and hormonal effects of two GnRH agonists in patients with prostate cancer. Eur Urol. 1997;32(4):397-403. PMID 9412795 A
10. Bolton EM, Lynch T. Are all gonadotrophin-releasing hormone agonists equivalent for the treatment of prostate cancer? A systematic review. BJU Int. 2018;122(3):371-383. PMID 29438592 (review)
11. Francis PA, Regan MM, Fleming GF, et al. Adjuvant ovarian suppression in premenopausal breast cancer. N Engl J Med. 2015;372(5):436-446. PMID 25495490 A
12. Pagani O, Regan MM, Walley BA, et al. Adjuvant exemestane with ovarian suppression in premenopausal breast cancer. N Engl J Med. 2014;371(2):107-118. PMID 24881463 A
13. Francis PA, Pagani O, Fleming GF, et al. Tailoring Adjuvant Endocrine Therapy for Premenopausal Breast Cancer. N Engl J Med. 2018;379(2):122-137. PMID 29863451 A
14. Del Mastro L, Boni L, Michelotti A, et al. Effect of the gonadotropin-releasing hormone analogue triptorelin on the occurrence of chemotherapy-induced early menopause in premenopausal women with breast cancer: a randomized trial. JAMA. 2011;306(3):269-276. PMID 21771987 A
15. Munster PN, Moore AP, Ismail-Khan R, et al. Randomized trial using gonadotropin-releasing hormone agonist triptorelin for the preservation of ovarian function during (neo)adjuvant chemotherapy for breast cancer. J Clin Oncol. 2012;30(5):533-538. PMID 22231041 A
16. Munhoz RR, Pereira AA, Sasse AD, et al. Gonadotropin-Releasing Hormone Agonists for Ovarian Function Preservation in Premenopausal Women Undergoing Chemotherapy for Early-Stage Breast Cancer: A Systematic Review and Meta-analysis. JAMA Oncol. 2016;2(1):65-73. PMID 26426573 A
17. Youssef MA, Van der Veen F, Al-Inany HG, et al. Gonadotropin-releasing hormone agonist versus HCG for oocyte triggering in antagonist-assisted reproductive technology. Cochrane Database Syst Rev. 2014;2014(10):CD008046. PMID 25358904 A
18. Klein K, Yang J, Aisenberg J, et al. Efficacy and safety of triptorelin 6-month formulation in patients with central precocious puberty. J Pediatr Endocrinol Metab. 2016;29(11):1241-1248. PMID 26887034 B
19. Cosson M, Querleu D, Donnez J, et al. Dienogest is as effective as triptorelin in the treatment of endometriosis after laparoscopic surgery: results of a prospective, multicenter, randomized study. Fertil Steril. 2002;77(4):684-692. PMID 11937116 A
20. Pirola I, Cappelli C, Delbarba A, et al. Anabolic steroids purchased on the Internet as a cause of prolonged hypogonadotropic hypogonadism. Fertil Steril. 2010;94(6):2331.e1-3. PMID 20416868 B
21. Saardpun N, Asawesna C, Kaewklam S, et al. The Impact of Triptorelin on Hormone Levels in Human and Its Metabolite Confirmation Using Liquid Chromatography-Ion Trap/Time-of-Flight Mass Spectrometry (LC/MS-IT-TOF) and Liquid Chromatography-Orbitrap (LC-Orbitrap) for Doping Control Analysis. Drug Test Anal. 2025;17(8):1443-1456. PMID 39757119 B
22. Sodero G. The Diagnostic Utility of the Triptorelin Stimulation Test Compared to the Standard Gonadotropin-Releasing Hormone Stimulation Test in Children with Idiopathic Central Precocious Puberty. Diseases. 2025;13(11):370. PMID 41294910 B
23. ClinicalTrials.gov. NCT06513962: Triptorelin for the Prevention of Ovarian Damage in Adolescents and Young Adults With Cancer (phase 3, sponsor Children's Oncology Group, recruiting, estimated 60 participants, primary completion estimated Oct 2029). Registry record, not peer-reviewed. ClinicalTrials.gov E, not peer-reviewed
24. ClinicalTrials.gov. NCT05982093: Elacestrant With/Without Triptorelin in Premenopausal Women With Luminal Breast Cancer (phase 2, sponsor SOLTI Breast Cancer Research Group, recruiting in Spain, estimated 96 participants, primary completion estimated Dec 2026). Registry record, not peer-reviewed. ClinicalTrials.gov E, not peer-reviewed
25. World Anti-Doping Agency. 2026 Prohibited List (in force 1 Jan 2026), class S2.2.1. WADA regulator
26. Finnish Center for Integrity in Sports (SUEK). Dopingaineryhmät ja -aineet 2026 (Finnish version of the WADA list), S2.2.1. SUEK regulator
27. Finland. Government Decree 705/2002 on the doping substances referred to in Chapter 44, section 16(1) of the Criminal Code. Finlex regulator

Research sources (PubMed) and regulatory, product-text and registry sources read on 15 Oct 2026.

Evidence levels: A = randomised human trial or meta-analysis · B = observational human study or case series · C = animal study · D = cell or laboratory study · E = not peer-reviewed · regulator = a regulator's assessment or decision, not research evidence. The marker official means official product information (summary of product characteristics or label); it is not research evidence. For a review, the level shows what kind of research the statement rests on. No level: statements that something has not been studied, reviews' interpretations, named hypotheses and the general rules in our certificate-of-analysis guide.

Content is general information about research, not medical advice. If you have symptoms, contact a healthcare professional.