Goserelin
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GnRH agonist decapeptide delivered as a subcutaneous implant; FDA-approved for prostate cancer, breast cancer, and endometriosis.
Quick Facts
| Property | Value |
|---|---|
| Also Known As | Zoladex, Goserelin acetate, ICI-118630 |
| Category | GnRH Agonist / Sexual Health / Reproductive |
| Sequence | pyroGlu-His-Trp-Ser-Tyr-D-Ser(tBu)-Leu-Arg-Pro-AzGly-NH2 |
| Molecular Weight | ~1269 Da |
| Molecular Formula | C59H84N18O14 |
| PubChem CID | 5311128 |
| Administration | SubQ implant (anterior abdominal wall) |
| Typical Dose Range | 3.6 mg monthly / 10.8 mg every 3 months |
| Half-Life | ~4.2 hours (free peptide); implant provides sustained release over 28 days or 12 weeks |
| Storage | Room temperature; do not freeze |
| FDA Status | Approved (1989) — Zoladex for advanced prostate cancer (1989), breast cancer (1995), endometriosis (1990), endometrial thinning (1996) |
| WADA Status | Not prohibited (FDA-approved medication) |
Mechanism of Action
Goserelin is a synthetic GnRH agonist analogue that acts through the same mechanism as other GnRH agonists: initial pituitary stimulation followed by receptor downregulation and sustained gonadotropin suppression. The D-Ser(tBu)6 substitution and azaglycine10 C-terminal modification enhance metabolic stability and receptor affinity compared to native GnRH.
Like leuprolide, goserelin produces an initial "flare" of LH and FSH release, causing a transient rise in testosterone (males) or estradiol (females) during the first 1-2 weeks. Continuous exposure then downregulates pituitary GnRH receptors, reducing LH and FSH to very low levels and achieving castrate testosterone (<50 ng/dL) in men or postmenopausal estradiol levels in women within 2-4 weeks.
Goserelin is uniquely formulated as a biodegradable cylindrical implant (Zoladex) containing the peptide in a D,L-lactic and glycolic acids copolymer matrix. The implant is injected subcutaneously in the anterior abdominal wall using a pre-loaded syringe, providing sustained drug release without the need for reconstitution. This delivery system was the first depot GnRH agonist implant approved (PMID: 9233866; PMID: 7624991).
Key Research Areas
- Prostate cancer with radiotherapy — Landmark EORTC trial demonstrated that goserelin combined with radiotherapy significantly improved 5-year overall survival (79% vs 62%) in locally advanced prostate cancer (PMID: 9233866)
- Prostate cancer vs surgical castration — RCTs confirmed goserelin produces equivalent objective response rates and survival compared to bilateral orchiectomy (PMID: 7624991)
- Premenopausal breast cancer — Twenty-year follow-up demonstrates durable benefit of adjuvant goserelin for ovarian suppression, with genomic high-risk patients showing the greatest benefit (HR 0.24) (PMID: 35862873)
- Endometriosis — Approved for pain management via ovarian suppression; comparable to other GnRH agonists
- Comparative GnRH agonist data — Included in systematic reviews confirming broad equivalence among GnRH agonists for prostate cancer (PMID: 29438592)
Evidence Level Summary
| Evidence Type | Count | Notes |
|---|---|---|
| Systematic reviews | 2 | LHRH meta-analysis; GnRH agonist equivalence review |
| Human RCTs | 3 | RT+goserelin vs RT; goserelin vs orchiectomy; breast cancer 20-year follow-up |
| Human observational | 0 | — |
| Animal in vivo | 0 | — |
| In vitro | 0 | — |
Clinical Applications
- Cancer Adjunct Therapy — Androgen deprivation for prostate cancer (alone or with radiotherapy); ovarian suppression for premenopausal breast cancer
- Sexual Health — Suppression of gonadal hormones
- Endometriosis — Pain management through estrogen suppression
- Fertility — Endometrial thinning before ablation procedures; ovarian suppression in ART protocols
Protocols Using This Peptide
- No current vault protocols use goserelin (FDA-approved prescription medication, not a research peptide)
Ageless Peps Products
- Not sold by Ageless Peps. Goserelin is an FDA-approved prescription medication (Zoladex) available only through licensed pharmacies and administered by healthcare providers.
Dosing Reference
FDA-Approved Dosing
| Indication | Dose | Route | Frequency | Duration | Source |
|---|---|---|---|---|---|
| Prostate cancer | 3.6 mg or 10.8 mg | SubQ implant | Monthly / q3mo | Ongoing | FDA label |
| Breast cancer (premenopausal) | 3.6 mg | SubQ implant | Monthly | 2-5 years (adjuvant) | FDA label |
| Endometriosis | 3.6 mg | SubQ implant | Monthly | 6 months max | FDA label |
| Endometrial thinning | 3.6 mg | SubQ implant | 1-2 doses preoperatively | Pre-ablation | FDA label |
Cycling
Not applicable in the traditional peptide cycling sense. Used continuously for cancer indications. For endometriosis, limited to 6 months due to bone mineral density concerns. In breast cancer, adjuvant ovarian suppression may continue for 2-5 years per current guidelines.
Contraindications & Safety
- Contraindications: Pregnancy (Category X/D depending on indication), hypersensitivity to GnRH or GnRH agonists, undiagnosed vaginal bleeding
- Common side effects: Hot flashes (57-75%), sexual dysfunction, decreased libido, headache, injection site pain/bruising, mood changes, sweating, bone pain (transient flare)
- Serious adverse effects: Bone mineral density loss (with prolonged use), testosterone flare (weeks 1-2), spinal cord compression (rare, from tumor flare), cardiovascular events, allergic reactions
- Drug interactions: Similar to other GnRH agonists; caution with QTc-prolonging drugs
- Pregnancy/nursing: Contraindicated; effective contraception required
- Special populations: Monitor bone density with extended use; subcutaneous implant requires proper injection technique (anterior abdominal wall below umbilicus)
Synergistic Combinations
- Leuprolide — Same drug class; alternative GnRH agonist options for different formulation preferences
- Triptorelin — Another GnRH agonist alternative
- Degarelix — GnRH antagonist; may offer cardiovascular advantages in high-risk patients
Related Research
| PMID | Title | Year | Study Type |
|---|---|---|---|
| 9233866 | Improved survival with radiotherapy and goserelin in locally advanced prostate cancer | 1997 | RCT |
| 7624991 | Goserelin versus orchiectomy in advanced prostate cancer: final results | 1995 | RCT |
| 35862873 | Twenty-year benefit from adjuvant goserelin and tamoxifen in premenopausal breast cancer | 2022 | RCT |
| 10744594 | Single-therapy androgen suppression: systematic review and meta-analysis | 2000 | Systematic Review |
| 29438592 | Are all GnRH agonists equivalent? A systematic review | 2018 | Systematic Review |
References
- PMID: 9233866 — Bolla et al., NEJM 1997
- PMID: 7624991 — Vogelzang et al., Urology 1995
- PMID: 35862873 — Johansson et al., J Clin Oncol 2022
- PMID: 10744594 — Seidenfeld et al., Ann Intern Med 2000
- PMID: 29438592 — Bolton & Lynch, BJU Int 2018
Related
#peptide #sexual-health #reproductive #fda-approved #not-sold #subq