Gonadorelin
Also called Synthetic GnRH; formerly Factrel
A synthetic version of gonadotropin-releasing hormone (GnRH), the signal that tells the pituitary to release LH and FSH. Its established role is in specialist reproductive medicine, not general hormone optimization.
Overview
What it is
A copy of the natural hypothalamic hormone GnRH. A diagnostic injection, a specialist pulse pump and occasional injections alongside testosterone are very different uses.
How it works
The hypothalamus normally releases GnRH in pulses, prompting LH and FSH, which act on the testes or ovaries. Timing matters: steady exposure and pulsed exposure produce different responses.
What the research shows
It is used to test pituitary function. The Endocrine Society suggests pulsatile GnRH for some women with functional hypothalamic amenorrhea who want to conceive. In 28 men with congenital GnRH deficiency, a gonadorelin pump produced sperm sooner than hCG/HMG (median 6 vs 14 months), though overall success did not differ.
Studied for
- Pituitary function testingdiagnostic
- Fertility in hypothalamic amenorrheapulsatile pump
- Congenital hypogonadotropic hypogonadism in mensmall study
Safety and regulatory status
Safety and side effects
The UK label lists headache, dizziness, flushing, nausea, injection-site changes and allergic reactions, and cautions use with pituitary adenomas, pregnancy and nursing. The AUA/ASRM guideline advises against testosterone alone for men who want fertility; adding gonadorelin should not be assumed to prevent suppression.
Regulatory status
Factrel (gonadorelin) was FDA approved in 1982 and is now discontinued. Compounded gonadorelin is not FDA approved.
Mixing and dosing reference
Reference information only. Read before using this section.
Gonadorelin (2 mg Vial) Dosage Protocol
- Vial
- 2 mg Gonadorelin
- Add diluent
- 2 mL
- Concentration
- 1 mg/mL
- 1 unit (U-100)
- 10 mcg in 0.01 mL
- Route
- Subcutaneous
- How often
- Non‑consecutive days (e.g., Mon/Wed/Fri) to mimic pulsatile GnRH release.
- Typical range
- 50–200 mcg per injection based on goals and response.
- Cycle length
- 4–8 weeks; include off‑periods to maintain pituitary sensitivity.
Standard / Maintenance Approach
| Week/Phase | Dose per Injection (mcg) | Units (mL) |
|---|---|---|
| Weeks 1–2 (Initiation) | 50 mcg | 5 units (0.05 mL) |
| Weeks 3–4 (Titration) | 100 mcg | 10 units (0.10 mL) |
| Weeks 5–8 (Maintenance) | 100–150 mcg | 10–15 units (0.10–0.15 mL) |
Advanced / Post-Cycle Support Approach
| Week/Phase | Dose per Injection (mcg) | Units (mL) |
|---|---|---|
| Days 1–7 (Burst) | 200 mcg | 20 units (0.20 mL) |
| Days 8–14 (Taper) | 100 mcg | 10 units (0.10 mL) |
| Week 3+ (Optional Maintenance) | 100 mcg 2–3×/wk | 10 units (0.10 mL) |
How to mix
- Draw 2.0 mL bacteriostatic water with a sterile syringe.
- Inject slowly down the vial wall; avoid foaming.
- Gently swirl/roll until dissolved (do not shake).
- Label concentration (1 mg/mL) and date; refrigerate at 2–8 °C (35.6–46.4 °F), protected from light.
Dosing details
- Start: 50–100 mcg per injection; assess tolerance before increasing.
- Target: 100–150 mcg per injection, 2–3 times weekly.
- Frequency: Non‑consecutive days (e.g., Mon/Wed/Fri) to mimic pulsatile GnRH release.
- Cycle Length: 4–8 weeks; include off‑periods to maintain pituitary sensitivity.
- Timing: Morning injections preferred; rotate injection sites.
Storage
- Lyophilized: Store at −20 °C (−4 °F) in dry, dark conditions; minimize moisture exposure.
- Reconstituted: Refrigerate at 2–8 °C (35.6–46.4 °F); follow product-specific use-by instructions and avoid freeze–thaw.
- Allow vials to reach room temperature before opening to reduce condensation uptake.
Administration technique
- Clean the vial stopper and skin with alcohol; allow to dry.
- Pinch a skinfold; insert the needle at 45–90° into subcutaneous tissue.
- Do not aspirate for subcutaneous injections; inject slowly and steadily.
- Rotate sites systematically (abdomen, thighs, upper arms) to avoid lipohypertrophy.
Important notes
- Use new sterile insulin syringes; dispose in a sharps container.
- Rotate injection sites (abdomen, thighs, upper arms) to reduce local irritation.
- Inject slowly; wait a few seconds before withdrawing the needle.
- Document each dose, date, and site rotation to maintain consistency.
- Limit continuous daily dosing to ≤14 days to prevent receptor desensitization.
Protocol source: PeptideDosages.com
Common questions
Does gonadorelin preserve fertility on TRT?
That has not been established. Fertility needs semen testing, not just a testosterone level.
Is it the same as hCG?
No. Gonadorelin acts on the pituitary; hCG acts directly on the testes or ovaries.
Is it FDA approved?
The original product was, but it is discontinued; current compounded products are not.
Related in Hormones and Reproductive Health
Sources and further reading (6)
- Marques P, et al. Physiology of GnRH and gonadotrophin secretion. Endotext, 2024.
- Endocrine Society. Functional hypothalamic amenorrhea guideline, 2017.
- Zhang L, et al. Pulsatile gonadorelin pump vs cyclical gonadotropin therapy in CHH men. Am J Mens Health, 2019.
- AUA/ASRM. Diagnosis and treatment of infertility in men, Part II.
- FDA. Factrel NDA 018123 record.
- Source summary: PeptideDosages.com research overview (rewritten for NVO).