RESEARCH MONOGRAPH · KDC-MN-284

Goserelin

May 9, 2026 Kodiac biolabs Research Revised May 30, 2026 2 min read

Our opinion on this compound

76/100

The cleanest of the GnRH agonist depot peptides on paper, but development concentrated everything in one implant formulation

Goserelin (Zoladex) is interesting because of what AstraZeneca did with the formulation rather than because of any radical departure on the peptide side. It's a 10-residue GnRH agonist, D-Ser(tBu) at position 6 and an azaglycine at position 10 instead of Pro-Gly-NH2. Mechanistically it does what the class does: receptor desensitization after the initial flare, resulting in chemical castration when run continuously.

The interesting thing about goserelin is that almost the entire clinical experience is with the subcutaneous biodegradable implant. The 3.6 mg 1-month and 10.8 mg 3-month formulations dominate, and the pharmacokinetic curves out of them are actually pretty smooth compared to some of the leuprolide depot products. For prostate cancer and breast cancer (estrogen-receptor-positive, premenopausal) the trials supporting it are strong. The ZIPP and TEXT/SOFT data are well-known reference points.

What we like: the implant pharmacokinetics. The cumulative release from PLGA copolymer matrices is reasonably reproducible, and the absorbed-dose-time profile is one of the smoother ones in the GnRH agonist class.

What we dont like is that this creates a research access problem. The implant formulation isnt useful for most research applications, and goserelin acetate as a free peptide is harder to source cleanly than triptorelin or leuprolide because the manufacturing scale outside the implant has historically been smaller. Some peptide suppliers do offer it but the QC variance is wider than the more common decapeptides in the class.

Sourcing aside, goserelin is mechanistically interchangeable with the other GnRH agonists for the receptor pharmacology work people actually do. If you're studying flare kinetics, gonadotropin suppression, or downstream HPG axis effects, it works fine. The peptide is structurally a little different from leuprolide and triptorelin but functionally similar at the receptor.

Honestly, for general GnRH agonist research, we'd usually reach for leuprolide or triptorelin first just because the supply chain is wider and the peptide-level data is easier to compare across studies. Goserelin earns its spot specifically when you care about the implant pharmacokinetics or when the clinical reference matters for a breast or prostate cancer model.

Evidence: 88
Mechanism: 90
Reliability: 82
Safety: 80
Sourcing: 65
Value: 60
Signal: 65
Staying power: 78

Plain-language summary Intrigue 50 / 100

Goserelin (Zoladex) is another GnRH agonist, distinguished from leuprolide and triptorelin not by mechanism (which is identical) but by formulation: a small biodegradable polymer rod implanted under the skin that releases the peptide gradually over 28 days or 12 weeks. Approved in 1989, used for prostate cancer, breast cancer (in premenopausal women), and endometriosis. The implant approach avoids the need for repeated intramuscular injections at the cost of a minor in-clinic procedure to insert the depot. Side effects mirror the broader GnRH agonist class: hot flashes, sexual dysfunction, bone loss, and mood effects from sex-hormone deprivation. Not stocked by Kodiac. This monograph is provided for research and educational reference.

Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.

Synthetic GnRH agonist (decapeptide)

A synthetic GnRH agonist provided as a subcutaneous depot implant; approved for prostate cancer, breast cancer, and endometriosis.

Abstract

Goserelin (5-oxo-L-prolyl-L-histidyl-L-tryptophyl-L-seryl-L-tyrosyl-O-(1,1-dimethylethyl)-D-seryl-L-leucyl-L-arginyl-2-(carbamoylimino)hydrazinyl-L-prolinamide; CAS 65807-02-5; molecular formula C59H84N18O14; molecular weight 1269.41) is a synthetic GnRH agonist decapeptide developed at ICI (now AstraZeneca) and approved by the FDA in 1989 under the trade name Zoladex. Distinguished within the GnRH agonist class by formulation: subcutaneous biodegradable polymer implant rod releasing peptide over 28 days (3.6 mg) or 12 weeks (10.8 mg). Mechanism is identical to leuprolide and triptorelin. Approved for advanced prostate cancer, advanced breast cancer in pre- and perimenopausal women, endometriosis, and uterine leiomyomata. The implant delivery is preferred in some clinical settings for compliance and steady plasma profile. Used as a reference GnRH agonist with depot implant delivery.

Mechanism of action

GnRH agonist decapeptide; identical pharmacology to leuprolide and triptorelin. Subcutaneous biodegradable implant for sustained release.

Reported research dose ranges

Clinical 3.6 mg subcutaneous implant monthly or 10.8 mg every 12 weeks.

References

Furr BJA, Hutchinson FG. A biodegradable delivery system for peptides: preclinical experience with the gonadotropin-releasing hormone agonist Zoladex. J Control Release 1992.
Cockshott ID. Clinical pharmacokinetics of goserelin. Clin Pharmacokinet 2000.
Tunn UW. A 6-month depot formulation of leuprolide acetate is safe and effective in daily clinical practice. World J Urol 2007.

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KDC-MN-284

The full reference document is provided strictly for research use only. It reports research dose ranges from the published literature, not instructions for use in humans or animals.

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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

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Goserelin

Abstract

Mechanism of action

Reported research dose ranges

References

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Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

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