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Triptorelin

Triptorelin: A Synthetic GnRH Decapeptide Agonist

Research summary. Triptorelin is a synthetic decapeptide analogue of gonadotropin-releasing hormone (GnRH) in which the natural glycine at position 6 is replaced by D-tryptophan, producing a long-acting agonist of the GnRH receptor. Continuous (non-pulsatile) administration produces an initial flare followed by sustained suppression of pituitary luteinizing hormone (LH) and follicle-stimulating hormone (FSH) release, leading to suppression of gonadal sex-steroid production. Triptorelin is approved in many jurisdictions for advanced prostate cancer (as part of androgen-deprivation strategies), endometriosis, central precocious puberty, and as a fertility-preservation adjunct, marketed under brand names including Decapeptyl and Trelstar. It is one of the longest-established peptide therapeutics in clinical use.

Molecular profile

  • Sequence: Pyr-His-Trp-Ser-Tyr-D-Trp-Leu-Arg-Pro-Gly-NH₂
  • Molecular formula: C₆₄H₈₂N₁₈O₁₃
  • Molecular weight: ~1311.5 g/mol
  • PubChem CID: 25074470
  • CAS number: 57773-63-4
  • Class: GnRH receptor agonist (superagonist)
  • Synonyms: D-Trp⁶-LHRH; Decapeptyl; Trelstar

Mechanism of action

Triptorelin acts at the pituitary GnRH receptor (GnRHR), a class A GPCR expressed on gonadotrophs:

  • Initial agonism and flare. A single dose stimulates LH and FSH release, producing a transient surge in testosterone (males) or estradiol (females).
  • Receptor downregulation under continuous exposure. Unlike the natural pulsatile GnRH signal, sustained occupancy of GnRHR produces receptor desensitisation and downregulation, leading to suppression of LH/FSH output and, secondarily, suppression of gonadal sex-steroid production.
  • Pulsatile vs. continuous administration. Pulsatile delivery can preserve gonadotrophin release and has been used in fertility research; depot formulations producing sustained exposure produce the chemical-castration effect that underlies the oncology and endometriosis applications.
  • D-Trp⁶ stabilisation. The D-amino acid substitution at position 6 increases resistance to enzymatic degradation, extending half-life relative to native GnRH.

Clinical research highlights

Advanced prostate cancer. Triptorelin is widely used as a component of androgen-deprivation therapy in advanced and metastatic prostate cancer. Suppression of testicular testosterone production reduces growth signalling for hormone-dependent prostate tumour cells. Initial flare is typically managed with concomitant anti-androgen administration.

Premenopausal hormone-receptor-positive breast cancer. GnRH-agonist ovarian suppression with triptorelin has been studied in combination with tamoxifen or aromatase inhibitors in premenopausal women with hormone-receptor-positive breast cancer.

Endometriosis. Sustained suppression of estradiol with triptorelin reduces ectopic endometrial-tissue activity and has been used to manage endometriosis-associated pain and lesion volume, including in pre-surgical settings.

Central precocious puberty. Triptorelin depot formulations are approved for central precocious puberty in children, suppressing premature pubertal progression.

Fertility preservation in chemotherapy. GnRH-agonist co-administration during gonadotoxic chemotherapy has been studied as a strategy to reduce premature ovarian insufficiency, with a substantial body of clinical-trial evidence on this question.

Provocative testing. Single-dose triptorelin has been used as a provocative test of pituitary–gonadal axis function in research and endocrine-evaluation contexts.

Current research status

Triptorelin is approved in the U.S. (Trelstar) and many other jurisdictions for advanced prostate cancer, with broader approvals for endometriosis and central precocious puberty in Europe and elsewhere. It is one of several GnRH-agonist analogues (alongside leuprolide, goserelin, and buserelin) in established clinical use. Where supplied for research, triptorelin is provided as a research-grade peptide and is not intended for self-administration.

Key takeaways for researchers

  • Triptorelin is a synthetic D-Trp⁶-substituted GnRH decapeptide that acts as a long-acting GnRHR agonist.
  • Continuous administration produces an initial gonadotrophin flare followed by sustained suppression of LH/FSH and gonadal sex steroids — the basis for its oncology and endometriosis applications.
  • It is FDA-approved for advanced prostate cancer (Trelstar) and approved in other jurisdictions for additional indications including endometriosis and central precocious puberty.
  • The D-amino acid substitution at position 6 increases enzymatic stability relative to native GnRH.
  • Outside of approved medical use, triptorelin research material is supplied for laboratory use only.

References

  1. Conn PM, Crowley WF Jr. Gonadotropin-releasing hormone and its analogs. Annu Rev Med. 1994;45:391–405.
  2. Lepor H. Comparison of single-agent androgen suppression for advanced prostate cancer. Rev Urol. 2005;7 Suppl 5:S3–S12.

This article is provided for educational and research purposes only. Triptorelin is a prescription medication where approved; outside of approved medical use, triptorelin research material is supplied for laboratory use only and is not intended for human consumption, diagnosis, treatment, cure, or prevention of any disease or condition. All work involving this peptide should be conducted by qualified personnel within an appropriate research setting and in compliance with applicable institutional and regulatory requirements.

Triptorelin | BonesLabs