Triptorelin

Trelstar, Triptodur (US); Decapeptyl, Diphereline, Gonapeptyl (EU and elsewhere); D-Trp6-GnRH; triptorelin pamoate/acetate/embonate

Sexual health, hormones & signalling

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Note on this profile. Triptorelin is an approved prescription medicine in most countries, not a research-only compound. This page explains the published science. Use outside a prescription, including grey-market vials and the single-shot "restart" protocols discussed online, carries real risks discussed below.

Summary

Class: Synthetic GnRH (LHRH) agonist decapeptide; native GnRH with D-tryptophan at position 6, which resists breakdown and raises receptor affinity
Mechanism: Initially stimulates, then desensitises pituitary GnRH receptors, shutting down LH/FSH and so testosterone or oestrogen to castrate/post-menopausal levels within 2–4 weeks
Routes studied: Intramuscular depot (1-, 3-, 6-monthly); daily subcutaneous (0.1 mg, IVF); single SC bolus as IVF trigger
Dose range reported: Approved (prostate cancer): 3.75 mg IM every 4 weeks, 11.25 mg every 12 weeks, 22.5 mg every 24 weeks. CPP: 22.5 mg every 24 weeks (Triptodur). Endometriosis/fibroids (EU): 3.75 mg monthly, up to 6 months. IVF down-regulation (EU): 0.1 mg SC daily. Agonist trigger (widely used, off-label): 0.2 mg SC once. Community "restart": 0.1 mg once, anecdotal
Half-life: ~3 hours for the peptide itself (IV, healthy men); depot formulations release for 1–6 months
Storage: Depot kits: room temperature, protect from freezing; reconstitute immediately before use with supplied diluent. Daily 0.1 mg solution: refrigerate
Regulatory status: Approved medicine (US, EU, UK, AU, ZA and many others)

Doses are as reported in studies or by the community — never recommendations.

1What it is

Triptorelin is a modified copy of the body's own GnRH, the hypothalamic hormone that tells the pituitary to release LH and FSH. Swapping one amino acid (position 6) for a D-tryptophan makes it far more stable and potent than native GnRH. It has been in clinical use since 1986 (Decapeptyl, Europe) and was approved in the US in 2000 (Trelstar). Its main use is to switch off testosterone in advanced prostate cancer, but it is also used for endometriosis, uterine fibroids, central precocious puberty, IVF protocols, premenopausal breast cancer (ovarian suppression) and, off-label in many places, puberty suppression in gender-affirming care.

2How it's thought to work

Flare. the first days of exposure stimulate the pituitary, so LH and testosterone rise for 1–2 weeks (clinically relevant in prostate cancer, where an anti-androgen is often given to cover it).

Down-regulation. continuous occupancy of GnRH receptors makes the pituitary stop responding. LH and FSH fall, and testosterone or oestradiol drop to castrate or post-menopausal levels, typically by week 3–4.

Reversibility. when the depot wears off the axis recovers over weeks to months, slower in older men and after long treatment.

Trigger use. a single bolus in a GnRH-antagonist IVF cycle produces a short LH surge that matures oocytes with far less ovarian hyperstimulation risk than hCG.

Continuous occupancy of the pituitary GnRH receptor. The natural signal arrives in pulses; a depot does not stop, and the receptor stops answering, which is what lowers testosterone or oestradiol.Schematic — not to scale

3What the research shows

Advanced prostate cancer (androgen deprivation)

Triptorelin pamoate achieves castrate testosterone in >90% of men by day 29 and maintains it; a randomised comparison with leuprolide found similar testosterone suppression and survival over 9 months (Heyns 2003, BJU Int). Long-acting formulations (3- and 6-month) match the 1-month depot. Androgen deprivation improves survival when combined with radiotherapy in high-risk localised disease (class evidence, e.g. Bolla 2010, Lancet Oncol, with goserelin; triptorelin used in later trials). [1]

Premenopausal breast cancer

In SOFT and TEXT (n≈4,690 combined), ovarian function suppression with triptorelin plus an aromatase inhibitor or tamoxifen improved disease-free survival in hormone-receptor-positive disease (Pagani 2014, NEJM; Francis 2015 and 2018, NEJM). Triptorelin during chemotherapy also reduced chemotherapy-induced early menopause in PROMISE-GIM6 (Del Mastro 2011, JAMA; Lambertini 2015, JAMA). [2][3][4]

Endometriosis and uterine fibroids

Reduces pelvic pain and lesion scores comparably to other GnRH ; shrinks fibroid volume by ~30–50% before surgery. Treatment is capped at 6 months because of bone loss, with "add-back" hormone therapy used to extend it (class evidence).

Graded A/B

Central precocious puberty

The 6-month 22.5 mg formulation suppressed LH to prepubertal levels in 93% of children at month 6 in an open-label phase 3 study (Klein 2016, J Pediatr Endocrinol Metab). [5]

IVF

Daily 0.1 mg for pituitary down-regulation ("long protocol") is standard in Europe. As a trigger in antagonist cycles, agonist triggering sharply reduces OHSS compared with hCG but lowers live-birth rate in fresh transfers unless the luteal phase is supported (Youssef 2014, Cochrane). [6]

Puberty suppression in transgender adolescents

Cohort data, mostly from the Netherlands, show effective suppression and acceptable short-term tolerability; long-term bone and neurodevelopmental outcomes remain under study and the practice is contested in several jurisdictions (de Vries 2011, J Sex Med). [7]

Single-dose "HPTA restart" after anabolic steroids

Community protocols describe a single 100 µg SC injection. No published study tests this. Pharmacologically a single small dose produces a brief LH/testosterone pulse; it does not reset anything. The real risk is dosing confusion: 100 mg (a depot-scale quantity) instead of 100 µg would suppress testosterone for months.

4Reported side effects and interactions

Literature-reported

Common (literature). hot flushes (50–70%), loss of libido, erectile dysfunction, fatigue, mood changes and depression, headache, injection-site pain, weight gain, gynaecomastia (men), vaginal dryness (women), bone mineral density loss with treatment beyond 6 months, loss of muscle mass.

Serious / warnings. tumour flare in the first weeks (bone pain, urinary obstruction, spinal cord compression in men with vertebral metastases); hyperglycaemia and new-onset diabetes; increased cardiovascular risk (class warning for GnRH ); QT prolongation; rare pituitary apoplexy in people with pituitary adenomas; hypersensitivity including anaphylaxis (rare); in children, early transient vaginal bleeding and reports of pseudotumour cerebri/idiopathic intracranial hypertension (class signal, added to US GnRH agonist labels in 2022).

Community-reported

prolonged low testosterone and libido after "restart" attempts; mood crashes; confusion between µg and mg products.

Interactions. hyperprolactinaemic drugs reduce GnRH receptor numbers; caution with QT-prolonging medicines (class IA/III antiarrhythmics, some antipsychotics); diagnostic pituitary-gonadal tests are invalid during and shortly after treatment.

Markers researchers commonly monitor

These follow label and oncology/gynaecology practice:

Marker	Why it's watched
Testosterone (men)	confirms castrate level (<50 ng/dL, ideally <20) and later recovery; the primary efficacy marker.
LH and FSH	fall after the flare; a stimulated LH <4 IU/L is the CPP target.
Oestradiol (women)	confirms suppression; also tracks add-back adequacy.
PSA	in prostate cancer, the disease marker.
Bone mineral density (DEXA)	before and after prolonged use; the main long-term cost of the class.
Fasting glucose, HbA1c, lipid panel	hyperglycaemia and metabolic shifts are class effects.
ECG (QTc)	in anyone on QT-prolonging drugs or with cardiac history.
Blood pressure and weight	cardiovascular class warning.

Free for everyone. Safety information is never behind a paywall.

5Reconstitution and handling

Depot kits come with their own and specific mixing steps; the suspension must be injected promptly. The 0.1 mg daily product is a ready solution. There is no community-style ; the calculator is not applicable to depot kits and is relevant only for converting mg/µg on the 0.1 mg product.

Open in calculator, pre-loaded →

6Commonly studied alongside

Leuprolide and nafarelin (same class, this batch), cetrorelix and ganirelix (the antagonist alternative in IVF), HCG (comparator trigger), gonadorelin (native GnRH), bicalutamide/flutamide (flare cover, not peptides), add-back norethisterone or tibolone (bone protection).

Informational cross-links. Not stack recommendations.

7Regulatory status by region

Region	Status (checked —)
United States	FDA-approved: Trelstar (prostate cancer), Triptodur (CPP). Not approved for endometriosis, fibroids, IVF or breast cancer in the US (off-label)
European Union	Authorised nationally (Decapeptyl, Diphereline, Gonapeptyl) for prostate cancer, endometriosis, fibroids, CPP, IVF and in some countries breast cancer
United Kingdom	MHRA-licensed (Decapeptyl SR, Gonapeptyl Depot); prescription-only
Australia	TGA-approved (Diphereline); prescription-only (S4)
South Africa	SAHPRA-registered (Decapeptyl); prescription-only
Sport	WADA S2: GnRH and its analogues, including triptorelin, are prohibited in males

8Open questions

Optimal duration and intermittent versus continuous androgen deprivation.
Long-term bone and cognitive outcomes of puberty suppression.
Whether triggering plus modified luteal support can match hCG for fresh-transfer live births.
There is no evidence base for any single-dose "restart" use.

9References

1Heyns CF et al. (2003). Comparative efficacy of triptorelin pamoate and leuprolide acetate in men with advanced prostate cancer. BJU Int. PubMed · DOI
2Pagani O et al. (2014). Adjuvant exemestane with ovarian suppression in premenopausal breast cancer (TEXT and SOFT). N Engl J Med. PubMed · DOI
3Francis PA et al. (2015). Adjuvant ovarian suppression in premenopausal breast cancer (SOFT). N Engl J Med. PubMed · DOI
4Del Mastro L et al. (2011). Effect of the gonadotropin-releasing hormone analogue triptorelin on the occurrence of chemotherapy-induced early menopause in premenopausal women with breast cancer (PROMISE-GIM6). JAMA. DOI
5Klein K et al. (2016). Efficacy and safety of triptorelin 6-month formulation in patients with central precocious puberty. J Pediatr Endocrinol Metab. PubMed · DOI
6Youssef MA et al. (2014). Gonadotropin-releasing hormone agonist versus HCG for oocyte triggering in antagonist-assisted reproductive technology. Cochrane Database Syst Rev. PubMed · DOI
7de Vries ALC et al. (2011). Puberty suppression in adolescents with gender identity disorder: a prospective follow-up study. J Sex Med. DOI
8Trelstar / Triptodur / Decapeptyl prescribing information (current labels). PubMed

References are being resolved to PubMed/DOI identifiers; links search PubMed for the citation until then.

10Community

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Self-reported side effects Phase 2

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11Page history

26 Oct 2026Profile published — awaiting medical review

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