Description
PrymaLab · Research use only
Triptorelin GnRH 2mg
[D-Trp6]-GnRH, a ten-residue GnRH agonist, 2 mg as a freeze-dried powder
Triptorelin is a synthetic analogue of gonadotropin-releasing hormone (GnRH) in which D-tryptophan replaces the glycine at position 6 of the native decapeptide. This vial holds 2 mg of it as a white freeze-dried powder. Research on triptorelin and its relatives covers why a D-amino acid at position 6 raises potency, how GnRH analogues act at the pituitary receptor, how triptorelin is cleared in people, and how it degrades in aqueous solution.
Specifications
| Property | Value |
|---|---|
| Compound | Triptorelin [D-Trp6]-GnRH |
| CAS number | 57773-63-4 |
| Molecular formula | C64H82N18O13 |
| Theoretical mass | 1311.5 Da |
| Sequence / structure | pGlu-HWSY-[D-Trp]-LRPG-NH₂ (10 residues; N-terminal pyroglutamate; C-terminal amide) |
| Label claim | 2 mg/vial |
| Form | Lyophilized (freeze-dried) powder or cake in a sealed glass vial with a rubber stopper and aluminium crimp cap |
| Storage, sealed | −20 °C, desiccated, dark |
| Purity specification | 99.0% or higher by RP-HPLC |
| Lot certificate | Results for the lot now shipping are in the certificate panel on this page |
| Safety data sheet | PL-SDS-174 |
One residue changed
The certificate gives the sequence as pGlu-HWSY-[D-Trp]-LRPG-NH2: the ten residues of native GnRH with the glycine at position 6 replaced by D-tryptophan, the mirror-image form of the amino acid. The formula is C64H82N18O13 and the theoretical mass 1311.5 Da, the figure to read the LC-MS identity result against. The chain now carries two tryptophans, at positions 3 and 6, which matters for its chemistry in solution.
Mass alone cannot tell D-tryptophan from L-tryptophan, because mirror-image residues weigh the same; the triptorelin guide discusses how the configuration at position 6 is confirmed. In molar terms, 2 mg of a 1311.5 Da peptide is about 1.5 µmol, slightly less once the certificate’s water content is allowed for. Triptorelin is also sold in solution, as a triptorelin preloaded pen and a triptorelin nasal spray.
What the research covers
Why position 6
Triptorelin grew out of structure-activity work on LH-RH in the 1970s. Coy and colleagues reported in 1976 that putting simple D-amino acids in place of the glycine at position 6 produced analogues with far greater gonadotropin-releasing activity than the natural hormone, both in vivo and in vitro1. Activity rose with the lipophilic character, and perhaps the size and aromaticity, of the new side chain: measured as LH release in immature male rats over six hours, [D-Ala6]-LH-RH was 7 times as active as LH-RH, [D-Phe6] 10 times and [D-Trp6] 13 times1. Replacing the C-terminal glycinamide with an ethylamide, which had raised the potency of the D-Ala6 and D-Leu6 analogues, made the D-Phe6 and D-Trp6 analogues less potent instead1.
Receptor binding and clearance
Müller and colleagues summarized triptorelin as binding GnRH receptors with higher affinity than the native hormone and as having a prolonged half-life because it resists enzymatic degradation2. Its target, the pituitary type I GnRH receptor, signals mainly through the G protein Gq, and Millar’s review of GnRH receptors noted that differences in ligand structure may direct which intracellular pathway the receptor engages3. Müller’s group measured triptorelin pharmacokinetics in an open study of 24 men: healthy volunteers, two groups with renal insufficiency of differing severity and one group with hepatic insufficiency2. Peak concentrations were similar in all four groups, total clearance fell as renal impairment worsened and was lowest with hepatic insufficiency, and serum levels fitted a three-compartment model2. Elimination half-lives in the three impaired groups were between 6.6 and 7.7 hours2.
Degradation in solution
Helm and Müller studied gonadorelin and triptorelin in aqueous solution across pH, temperature, buffer species, buffer concentration and ionic strength, using stability-indicating HPLC4. The two peptides degraded in similar ways and were most stable at about pH 5; acetate buffer was the most favorable, phosphate caused more degradation, and ionic strength had no significant effect4. For triptorelin in acetate buffer at pH 5 with mannitol, they predicted a t90 of 7.7 years at 20 °C4. Hoitink and colleagues later traced the degradation of triptorelin, buserelin and goserelin to a small number of residues, with the L-serine (position 4 in triptorelin) involved in both backbone hydrolysis and epimerization5. The two tryptophans add an oxidation route. In a hydrogen peroxide model, Simat and Steinhart found that free tryptophan degraded fastest, short tryptophan peptides more slowly and the protein lysozyme slowest, with the pyrrole part of the indole ring the most susceptible and oxindolylalanine and N-formylkynurenine the main products identified6.
What is not established
The stability figures come from buffered solutions designed for the purpose, not from the bacteriostatic water used in PrymaLab’s pen and spray, and none of the studies used PrymaLab material. The human data cited here are pharmacokinetic only. The clinical pharmacology, regulatory status and safety record of triptorelin are covered in the triptorelin guide.
How each lot is tested
Every lot is tested in PrymaLab’s own laboratory in Ashland, Kentucky before release: RP-HPLC for purity, LC-MS for identity, Karl Fischer titration for water, LAL for endotoxin and USP <71> for sterility. The results for the lot now shipping are in the certificate panel on this page, and the certificate number, key and QR code can be checked on the verify page. These are in-house results from PrymaLab Analytical, not an independent test, and the lab is not accredited to ISO 17025. The third-party testing guarantee on this page still applies: if any independent laboratory finds the wrong compound, or less than the stated purity or amount, the order is refunded and the cost of the test is reimbursed.
Frequently asked questions
How does triptorelin differ from gonadorelin?
Gonadorelin is native GnRH. Triptorelin has the same ten residues except position 6, where glycine is replaced by D-tryptophan. In rat studies that substitution made the peptide 13 times as active at releasing LH, and it slows enzymatic breakdown.
Can the LC-MS result tell D-tryptophan from L-tryptophan?
No. Mirror-image amino acids have identical masses, so the LC-MS result confirms the 1311.5 Da mass but not the configuration at position 6. The triptorelin guide explains which other methods are used to confirm it.
How do the vial, pen and spray compare?
All three contain the same peptide. The vial holds 2 mg of dry powder kept at −20 °C. The pen holds 6 mg in 3 mL of bacteriostatic water, 2 mg/mL, and the spray holds 2 mg in a metered bottle; both solutions are kept at 2 to 8 °C and never frozen.
How should the vial be stored?
Sealed at −20 °C, dry and protected from light. Allow it to reach room temperature before opening to avoid condensation on the powder. Once reconstituted, keep the solution at 2 to 8 °C and away from light, and use it within a period your laboratory has established.
Is triptorelin for human use?
Not this product. It is a research chemical, not approved by the FDA or any other authority for human or veterinary use, and it must not be given to people or animals.
References
- Coy DH, Vilchez-Martinez JA, Coy EJ, et al. Analogs of luteinizing hormone-releasing hormone with increased biological activity produced by D-amino acid substitutions in position 6. J Med Chem. 1976;19(3):423-5. DOI · PubMed
- Müller FO, Terblanchè J, Schall R, et al. Pharmacokinetics of triptorelin after intravenous bolus administration in healthy males and in males with renal or hepatic insufficiency. Br J Clin Pharmacol. 1997;44(4):335-41. DOI · PubMed
- Millar RP, Lu ZL, Pawson AJ, et al. Gonadotropin-releasing hormone receptors. Endocr Rev. 2004;25(2):235-75. DOI · PubMed
- Helm VJ, Müller BW. Stability of gonadorelin and triptorelin in aqueous solution. Pharm Res. 1990;7(12):1253-6. DOI · PubMed
- Hoitink MA, Beijnen JH, Boschma MU, et al. Degradation kinetics of three gonadorelin analogues: developing a method for calculating epimerization parameters. Pharm Res. 1998;15(9):1449-55. DOI · PubMed
- Simat TJ, Steinhart H. Oxidation of Free Tryptophan and Tryptophan Residues in Peptides and Proteins. J Agric Food Chem. 1998;46(2):490-498. DOI · PubMed
Research use only
For laboratory research use only. Triptorelin GnRH 2mg is not a drug, food, cosmetic or dietary supplement, is not approved by the FDA or any comparable authority for human or veterinary use, and must not be given to people or animals. It is sold to qualified researchers and institutions, and the buyer is responsible for lawful handling and disposal.
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