Gonadorelin
Gonadorelin diacetate tetrahydrate / Gonadorelin hydrochloride
Also known as: Cystorelin · Fertagyl · Factrel · Fertalin · Ovacyst · follicle stimulating hormone-releasing factor · GnRH · gonadoliberin · gonadorelinum · gonadotrophin-releasing hormone · LH/FSH-RF · LH/FSH-RH · LH-RF · LH-RH · luliberin · luteinising hormone-releasing factor
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Audited v13 dosing evidence
Structured calculator evidenceImprovement in semen quality (extra-label)
Verified clinician required
Alternative schedules — select one
- once
- q7d
NA
Governing clinical context (2)
- Most gonadorelin products (Factrel®, Fertagyl®, and GONABreed®) should be refrigerated at 2°C to 8°C (36°F to 46°F) for long-term storage. One product (Cystorelin®) should be stored at or below 25°C (77°F), with brief excursions to 30°C (86°F) permitted. Discard dates for in-use vials vary by manufacturer:
- ■ GONABreed®: 180 days after first use, and in-use vials may be stored at temperatures up to 25°C (77°F)
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Gonadorelin is a synthetic hypothalamic hormone (GnRH analogue) used primarily in veterinary medicine to treat reproductive disorders such as ovarian follicular cysts, particularly in dairy cattle.
Key highlights:
- Very short duration of action (minutes).
- Used off-label in small animals for diagnostic purposes (e.g., differentiating castrated vs. intact animals, identifying retained testicles) and to induce estrus or ovulation.
- No slaughter or milk withdrawal required when used as labeled in food animals.
- Highly safe with virtually no reported adverse effects.
Mechanism of action
Gonadorelin acts as a synthetic GnRH (Gonadotropin-Releasing Hormone) → binds to receptors on the anterior pituitary gland → stimulates a surge-like release of FSH (Follicle Stimulating Hormone) and LH (Luteinizing Hormone).
- In females (cows, ewes, cats), this LH surge can induce ovulation or luteinization of cystic follicles.
- In males, it stimulates testosterone release, which is useful for diagnostic stimulation testing.
- Note: A constant infusion initially stimulates LH/FSH release, but eventually causes receptor downregulation and levels return to baseline.
Safety & warnings
Contraindications
- None noted on the label
Adverse effects
- None reported
- Hypersensitivity reactions are highly unlikely with synthetic preparations
Precautions
None are noted on the label. In humans, the FDA categorizes this drug as category B for use during pregnancy.
Monitoring
- Clinical efficacy (e.g., resolution of cystic ovaries, induction of estrus)
- Serum progesterone levels (for ovarian remnant or cystic ovary verification)
- Serum testosterone levels (for cryptorchidism/castration testing)
Pharmacokinetics
Distribution
Rapidly distributed to extracellular fluid. Distribution half-life of about 2 minutes in pigs.
Metabolism
Metabolized into inactive peptide fragments. In humans, approximately half the dose is excreted in urine as metabolites within one hour.
Elimination
Eliminated in urine and feces.
Overdose
In doses of up to 120 micrograms/kg, no untoward effects were noted in several species of test animals. Gonadorelin is unlikely to cause significant adverse effects after inadvertent overdosage.
Available products
Formulations
- Injection
Veterinary
- Gonadorelin (diacetate tetrahydrate) for Injection: 50 micrograms/mL, 2 mL single-use or 10 mL multi-dose vials (Cystorelin, Fertagyl, Fertalin, Ovacyst)
- Gonadorelin HCl Solution for Injection: 50 micrograms/mL in 2 mL single-use, and 20 mL multi-dose vials (Factrel)
Human-labeled
- Gonadorelin HCl Powder for Injection (lyophilized): 100 micrograms/vial & 500 micrograms/vial with 2 mL sterile diluent (Factrel)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store in the refrigerator (2-8°C). Because bacterial contamination can inactivate the product, multi-dose vials should be used completely and as rapidly as possible.
Client information
Veterinary Administration Only: This medication is typically administered in the clinic by your veterinarian for diagnostic testing or reproductive management.
- Purpose: Used to diagnose retained testicles, check for ovarian remnants after spaying, or treat specific reproductive conditions.
- Safety: It is a synthetic version of a naturally occurring hormone and is considered very safe with no known side effects in pets.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.