| HS Code | 238013 |
| Chemicalname | Gonadotropin-Releasing Hormone (GnRH), also known as Gonadorelin |
| Casnumber | 33515-09-2 |
| Molecularformula | C55H75N17O13 |
| Molecularweight | 1182.29 g/mol |
| Appearance | White to off-white lyophilized powder or crystalline solid |
| Solubility | Soluble in water, saline, and dilute acetic acid; sparingly soluble in ethanol |
| Meltingpoint | Decomposes before melting, typically above 180°C |
| Storageconditions | Store at 2–8°C, protected from light and moisture; solutions stable at 2–8°C for limited periods |
| Shelflife | Typically 24 months when stored unopened under recommended conditions |
| Purityassay | ≥98% (HPLC) for veterinary grade API |
| Mechanismofaction | Stimulates pituitary release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) |
As an accredited Gonadotropin Releasing Hormone (GnRH) Veterinary Grade API for Tablets / Injections / Capsules / Powders / Granules / Premix / Solutions factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged in sealed multilayer laminated foil bags inside HDPE drums, 25 kg net per drum, with tamper-evident seals and labels. |
| Container Loading (20′ FCL) | 20′ FCL container loaded with GnRH veterinary-grade API, packaged in approved drums for tablets, injections, capsules, powders, granules, premix, and solutions. |
| Shipping | Ship under temperature-controlled conditions (2–8°C), protected from light and moisture. Use sealed pharmaceutical-grade containers with desiccants, plus insulated packaging and coolant packs for air/sea freight. Include Certificate of Analysis, Material Safety Data Sheet, and temperature-logger documentation to ensure stability, compliance, and safe delivery. |
| Storage | Store GnRH veterinary grade API in a tightly sealed, light-resistant container, away from moisture and heat. Recommended storage is refrigerated at 2–8°C to maintain peptide stability. Avoid freezing. Ensure cool, dry conditions and protection from direct sunlight for tablets, capsules, powders, granules, premix, solutions, or injections. Use before expiry. |
| Shelf Life | Shelf life typically 24–36 months when stored cool, dry, and protected from light, moisture, and extreme temperatures. |
In lactating Holstein-Friesian herds managed under fixed-time artificial insemination, the dominant downstream use of gonadorelin acetate is synchronisation of follicular recruitment and ovulation within Ovsynch-derived protocols. The active substance is compounded into sterile aqueous injection solution at 50 µg/mL, equivalent to 0.005% w/v, with osmolality controlled at 280–310 mOsm/kg and pH adjusted to 5.5 ± 0.5 using acetate buffer. Production-scale preparation follows EU GMP Annex 1 aseptic processing, in which the bulk solution is passed through a 0.22 µm PVDF capsule filter into depyrogenated Type I borosilicate vials under Grade A unidirectional airflow with Grade B background. Terminal sterilisation is not applied because the decapeptide undergoes hydrolytic degradation above 40 °C; finished product release therefore requires sterility testing per USP <71>, bacterial endotoxin verification per USP <85> with an active substance limit of ≤2.5 EU/mg, and visible particulate inspection per USP <790>. Multi-dose aqueous formats incorporate benzyl alcohol at 0.9% w/v and require preservative effectiveness validation according to USP <51>. Residual-solvent compliance is anchored to VICH GL18(R2), and active substance characterisation follows Ph. Eur. monograph 0828 for gonadorelin acetate. Finished formats include 2 mL single-dose vials, 10 mL multi-dose vials, and lyophilised powder for reconstitution containing 100 µg gonadorelin acetate with mannitol bulking excipient, giving an active content of 1.0% w/w in the dried cake. Tablets, capsules, powders, granules, and oral premixes are not standard downstream formats for this API in food-producing species because first-pass proteolysis and ruminal degradation reduce intact decapeptide bioavailability below analytically quantifiable plasma concentrations.
| Control Point | Reference Standard | Acceptance Boundary in This Application |
|---|---|---|
| Sterility of injectable finished product | USP <71> | No growth after 14 days of incubation |
| Bacterial endotoxins | USP <85> | ≤2.5 EU/mg for parenteral active substance specification |
| Visible particulates | USP <790> | Inspection rejects containers with sub-visible or visible particle counts exceeding compendial thresholds |
| Uniformity of dosage units for lyophilised powders | USP <905> | Acceptance value ≤15.0 |
| Residual solvents | VICH GL18(R2) | Class 1 solvents absent; Class 2 solvents within permitted daily exposure limits |
| Aseptic processing environment | ISO 13408-1:2008 | Grade A at rest ≤3,520 particles/m³ at ≥0.5 µm |
Equine practitioners using gonadorelin acetate in anovulatory or transitional mares rely on the same 50 µg/mL injectable concentration, giving 0.005% w/v active peptide, but the production route differs in packaging validation because equine veterinary clinics frequently prefer low-headspace vials that reduce oxidative degradation of the tryptophan residue at position 3 of the decapeptide sequence. Aseptic filling for equine products uses a 0.22 µm membrane filter, nitrogen overlay to maintain headspace oxygen below 0.5% v/v, and sterile stoppers with low extractable profiles. Batch records from equine filling campaigns have shown higher rejection rates when stopper moisture exceeds 0.5% w/w, because surface adsorption of the peptide to rubber increases sub-visible particle formation. The solution is held at 2–8 °C after filling and protected from light; pH remains 5.5 ± 0.5. Compliance for the equine product includes USP <71>, USP <85>, USP <790>, and VICH GL18(R2) for residual solvents, while active substance release follows Ph. Eur. monograph 0828. Finished product types include 2 mL single-dose vials, 10 mL multi-dose vials, and lyophilised powder with diluent ampoules; the lyophilised format is preferred in ambulatory practice because the dried cake is less sensitive to short-term temperature excursions than the aqueous solution. Tablets, capsules, granules, powders, and premixes are not appropriate for equine oral administration because intestinal proteolysis and negligible peptide permeability exclude therapeutic systemic exposure.
Within high-throughput swine multiplication units, the synchronization of ovulation for fixed-time insemination uses the API as a short-acting trigger injection prepared at 50 µg/mL, corresponding to 0.005% w/v gonadorelin acetate. The liquid formulation is adjusted to pH 5.5 ± 0.5 and includes sodium chloride at 0.9% w/v for isotonicity. Multi-dose vials require preservative effectiveness testing per USP <51>; a typical preservative system contains benzyl alcohol at 0.9% w/v. Downstream filling on automated lines uses a 16-head peristaltic pump with a fill tolerance of ±0.08 mL for 50 mL and 100 mL vials, and stopper insertion is performed under nitrogen flush to maintain headspace oxygen below 1.0% v/v. Freeze-thaw is an operational boundary: exposure of the aqueous solution to a single freeze-thaw cycle can reduce peptide potency by more than 10% due aggregation. Release testing follows USP <71> for sterility, USP <85> for endotoxins, and USP <790> for visible particulates; active substance specification is aligned with Ph. Eur. monograph 0828 and VICH GL18(R2). Terminal formats are confined to ready-to-use sterile vials because dry powders, granules, and premixes do not survive the porcine gastric environment and are not a viable downstream presentation for intact GnRH.
In accelerated lambing and embryo transfer programmes, the API is positioned as a pre-ovulatory trigger after progestagen priming rather than as a standalone therapy. Injectable solution is prepared at 50 µg/mL, giving an API loading of 0.005% w/v, with pH 5.5 ± 0.5 and osmolality 290 mOsm/kg. For breeding centres that require reduced cold-chain dependence, lyophilised powder containing 50 µg or 100 µg gonadorelin acetate per vial is produced using a cGMP freeze-dryer with shelf temperature −45 °C, primary drying at −15 °C for 14 h, and secondary drying at 25 °C for 4 h. Karl Fischer titration of the dried cake must show residual moisture below 1.0% w/w; cake collapse during primary drying is controlled by maintaining chamber pressure below 0.1 mbar. The active content in a typical 50 µg vial with mannitol as bulking excipient is 0.5% w/w when total cake mass is 10 mg, and 1.0% w/w for 100 µg in the same matrix. Compliance standards include USP <905> for uniformity of dosage units with acceptance value ≤15.0, USP <71>, USP <85>, Ph. Eur. monograph 0828, and VICH GL18(R2). Finished product types are single-dose lyophilised vials, 10 mL multi-dose aqueous vials, and diluent ampoules. Oral tablets, capsules, powders, granules, and premixes are not formulated for sheep or goats because rumen microflora rapidly degrade the peptide and published pharmacokinetic data for oral gonadorelin in small ruminants is limited.
Teleost hatcheries that replace carp pituitary homogenate with defined GnRH preparations use the aqueous injectable format at reported concentrations of 20–50 µg/mL, corresponding to 0.002–0.005% w/v gonadorelin acetate in buffered saline. Sustained-release cholesterol pellets loaded at 0.05–0.20% w/w have been described in experimental broodstock studies, although published data for commercial matrix loadings across all teleost species is limited. Injectable production follows the same aseptic route as mammalian products: 0.22 µm filtration, Grade A filling, and cold storage at 2–8 °C. Hatchery field reports identify pH drift below 4.5 or above 7.0 as a cause of reduced spawning response, because acetate buffer exhaustion accelerates peptide degradation. Environmental compliance is more demanding in aquaculture: the manufacturer must provide Phase I and Phase II environmental impact data under VICH GL6 and VICH GL38 for waterborne release, alongside VICH GL18(R2) residual solvent limits and EU Regulation 2019/6 authorisation. Terminal product types include 10 mL amber sterile vials, lyophilised powder for reconstitution, and compressed pellets for broodstock implantation. Oral premixes and granules are not appropriate in aquaculture because waterborne peptide leaching is uncontrolled and gastrointestinal absorption of the intact decapeptide in teleosts is insufficiently documented.
For non-domestic felids, canids, and camelids, captive breeding programmes use the API as a parenteral trigger where chorionic gonadotropin supply is unreliable or where reduced antigenicity is desired. The lyophilised powder is reconstituted to 50 µg/mL (0.005% w/v) before intramuscular injection, while dried cake formats contain 50 µg or 100 µg gonadorelin acetate with mannitol, yielding active contents of 0.5–1.0% w/w. Aseptic compounding follows USP <797> for extemporaneous preparation, and in the United States use from bulk API in non-food animals is governed by 21 CFR 530. Production-scale lyophilisation for zoo stock is identical to ovine/caprine formats: shelf temperature −45 °C, primary drying −15 °C for 14 h, secondary drying 25 °C for 4 h, and residual moisture <1.0% w/w. Finished product types include sterile vials, chilled diluent packs, and lyophilised single-dose kits. Oral tablets, capsules, powders, granules, and premixes are excluded from zoo practice because the intact decapeptide does not survive gastrointestinal proteolysis and because voluntary oral intake in restrained non-domestic species is operationally unreliable.
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As the synthetic decapeptide corresponding to endogenous mammalian gonadotropin-releasing hormone (GnRH), gonadorelin acetate is supplied as a veterinary-grade active pharmaceutical ingredient for the manufacture of tablets, injectable solutions, capsules, powders, granules, premixes, and oral solutions. The peptide sequence pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH₂ has a free-base molar mass of 1182.3 g/mol; the acetate salt is the predominant commercial form because of improved aqueous solubility and lyophilisate stability. The veterinary designation requires compliance with the current Ph. Eur. monograph for gonadorelin acetate, relevant VICH guidance including VICH GL18 for residual solvents, and manufacture under GMP Part II for APIs. No single model designation applies; the material is identified by peptide sequence, acetate content, and pharmacopeial monograph rather than a proprietary model number. The API is used in cattle reproduction protocols for ovulation induction and treatment of ovarian follicular cysts, and in species-specific reproductive management; its short plasma half-life requires precise formulation and route-specific delivery.
From a production-scale perspective, the API is manufactured by solid-phase peptide synthesis using Fmoc chemistry; the C-terminal glycine is anchored to a resin, and amino acids are coupled sequentially. Cleavage from the resin with trifluoroacetic acid yields crude peptide; purification is by preparative reversed-phase high-performance liquid chromatography with acetonitrile/water gradients. The final product is converted to acetate salt by ion-exchange or lyophilization from dilute acetic acid. Residual trifluoroacetic acid is controlled because it influences pH and cell-based bioactivity. Peptide content is determined by Ph. Eur. 2.2.29 with UV detection at 220 nm; related substances are quantified by area normalisation against the main peak. The synthesis route creates specific impurities such as deletion peptides and oxidised tryptophan derivatives, which are resolved under the pharmacopeial gradient method. Batch-to-batch variability in residual water and acetate content affects the reconstitution time of lyophilized injection powders; control of lyophilization chamber pressure between 0.2 mbar and 0.6 mbar and shelf temperature ramps below 30 °C is necessary to preserve cake structure.
In aqueous formulations, solubility of gonadorelin acetate is pH-dependent; clarity of reconstituted injection solutions is typically maintained at pH 4.5–6.0. Outside this range, aggregation of the hydrophobic residues 5-oxoproline, tryptophan, and tyrosine becomes detectable by dynamic light scattering. Lyophilized injection-grade powder should have a residual moisture content not exceeding 8.0% by Ph. Eur. 2.2.32, and the headspace oxygen content in vials is controlled because the sequence contains no methionine but is susceptible to tryptophan oxidation and histidine deamidation under alkaline conditions. Sterile filtration of bulk solution before lyophilization is performed through 0.22 µm membranes; endotoxin acceptance limits for parenteral veterinary products are established by Ph. Eur. 2.6.14, with limits aligned to target species and maximum dose. Non-sterile API intended for terminal sterilisation must demonstrate bioburden below the sterilising filter capacity and absence of Escherichia coli under Ph. Eur. 2.6.13. Phosphate-buffered solutions above pH 7.0 show elevated related substances in accelerated stability studies; therefore, acetate or citrate buffers are preferred for reconstitution.
Particle size distribution of the API is determined by laser diffraction according to ISO 13320:2020. Milled batches intended for capsules and tablets typically have d10 10 µm, d50 40 µm, and d90 150 µm. The solid state of gonadorelin acetate is predominantly amorphous after lyophilisation; X-ray powder diffraction shows a diffuse halo rather than sharp reflections. Amorphous material has higher water uptake than crystalline salts, which affects flowability and chemical stability. Conditioning at 25 °C and 40% RH for 24 h before weighing is used to reduce electrostatic charging during dry processing. For injection-grade powder, particle size is less critical because it is dissolved before sterilisation, but residual moisture and cake integrity are release-critical.
Due to rapid proteolytic cleavage in the gastrointestinal tract and first-pass hepatic extraction, solid oral presentations of native GnRH—tablets, capsules, granules, and powder premixes—are not equivalent to injectable solutions. Published data for this specific configuration is limited; oral bioavailability of unmodified gonadorelin acetate is generally reported as low and variable, with degradation initiated by gastric pepsin and intestinal brush-border peptidases. Tableting of the acetate salt without prior granulation results in poor compressibility and sticking due to its hygroscopic nature; wet granulation requires a non-aqueous binder system such as polyvinylpyrrolidone dissolved in isopropanol because water exposure above RH 60% at 25 °C produces agglomeration and peptide hydrolysis. Capsule filling requires particle size distribution with d90 below 150 µm and flowability characterized by Carr index below 25 if high-speed encapsulation is used. Premix production for medicated feed requires the API be adsorbed onto a carrier or microencapsulated with lipid or enteric polymers to protect the peptide from moisture and enzymatic attack. Potency retention in finished feed at 25 °C and 60% relative humidity is frequently below 90% after 30 days unless stabilisers and moisture-barrier packaging are used. Tablets, capsules, powders, granules, and premixes of this API are therefore development-sensitive and are not directly interchangeable with injection-grade material without formulation-specific stability verification.
When the route shifts from sterile injectable solution to oral feed premix, the critical quality attributes change from endotoxin and sub-visible particle control to homogeneity, particle size distribution, and moisture resistance. The same API lot may be accepted for oral premix with wider moisture and bioburden limits than the injection-grade lot, but additional controls for blend uniformity are required. Mixing studies in double-cone blenders with fill volumes of 50–70% have shown that demixing of uncoated GnRH acetate from lactose monohydrate carriers occurs when the particle size ratio exceeds 1:10; high-shear granulation reduces segregation but exposes the peptide to local temperatures of 35–45 °C, which is acceptable only for short residence times below 20 min. Direct compression of tablets containing native GnRH acetate is limited by the low weight fraction of API, typically below 0.1% w/w, requiring multi-step geometric dilution. In premix applications for aquaculture, the API may be dissolved in a coating solution and sprayed onto extruded feed pellets under vacuum, with recovered potency verified by Ph. Eur. 2.2.29. Reducing sugars are avoided in aqueous coating because they accelerate degradation and discolouration; lactose-free carriers such as microcrystalline cellulose and calcium hydrogen phosphate dihydrate are preferred.
Native gonadorelin differs from veterinary GnRH analogues at positions 6 and 9/10, which modifies receptor affinity and proteolytic stability. The table summarises structural distinctions that affect formulation and dosing.
| Substance | Structural distinction | Formulation consequence |
|---|---|---|
| Gonadorelin (native GnRH) | Gly at position 6; Gly-NH₂ at position 10 | Short plasma elimination half-life, approximately 2–8 min; requires rapid-release injectable or stabilised solid dosage form |
| Buserelin | D-Ser(OtBu) at position 6; Pro-NHEt at position 9 | Increased resistance to peptidase cleavage; suitable for repeated injection or implant |
| Deslorelin | D-Trp at position 6; Pro-NHEt at position 9 | Sustained-release implants used in equine and small animal reproduction |
Unlike buserelin and deslorelin, native gonadorelin has no D-amino acid at position 6, so it is rapidly degraded by neutral endopeptidase and carboxypeptidases. This short half-life makes it appropriate for acute ovulation induction rather than long-term suppression. The acetate salt differs from pamoate or embonate salts used in depot formulations of other GnRH analogues; gonadorelin acetate has no inherent depot effect unless formulated in an implant or in situ gel matrix.
For cattle, the injectable dose of gonadorelin acetate is commonly 100–150 µg per animal for ovulation induction, depending on national registration. For aquaculture species, feed-based administration requires higher doses because of dilution and variable ingestion; published data for this specific configuration is limited. The oral route in monogastric animals is not recommended for native GnRH without an absorption-enhancing formulation, because gastric acidity at pH 1.5–3.0 unfolds the peptide and accelerates cleavage. In ruminants, rumen microbial proteases degrade the unprotected peptide before intestinal absorption; thus, rumen-protected granules or intra-ruminal devices are required if oral cavity delivery is bypassed.
For veterinary parenteral products, the release boundary is set by residual solvent, endotoxin, and related substances rather than by a single assay value. Residual solvents are controlled under VICH GL18 and Ph. Eur. 5.4, with Class 1 solvents absent and Class 2 solvents such as acetonitrile and methanol limited to the corresponding permitted daily exposure values; trifluoroacetic acid from solid-phase synthesis is not a residual solvent but is controlled as a related substance or counterion impurity. Elemental impurities are controlled according to ICH Q3D, with particular attention to arsenic, cadmium, mercury, and lead because of the multi-step peptide synthesis and lyophilisation process. The API is hygroscopic; storage conditions are typically −20 °C to 5 °C in sealed, light-protective containers under nitrogen or argon. Repeated warming to room temperature for sampling without desiccant leads to moisture uptake and peptide aggregation; containers should be equilibrated before opening. The acetate counterion is volatile under lyophilization; incomplete acetate removal leads to pH shift in reconstituted solutions. Avoid combination with strongly alkaline buffers, metal ions such as copper and iron that catalyse tryptophan oxidation, and oxidising disinfectants. Sterile injectable solutions should not be autoclaved after compounding because terminal heat sterilisation at 121 °C for 15 min produces hydrolysis of amide bonds and significant potency loss. For solid dosage forms, keep RH below 40% during processing and avoid milling after final drying because mechanical stress reduces crystallinity and increases amorphous content, accelerating degradation. The veterinary API is not for human use; distribution is controlled by veterinary prescription regulations in the target jurisdiction.
