Triptorelin

Triptorelin is a synthetic decapeptide analog of gonadotropin-releasing hormone (GnRH), differing from the native hormone (built on this site as Gonadorelin) by a single amino acid substitution: D-tryptophan replaces glycine at position 6. This single substitution is proposed to confer roughly 100-fold greater GnRH receptor binding affinity and substantially greater resistance to enzymatic degradation compared to native GnRH, extending its effective duration of action from native GnRH's few-minute half-life to weeks or months, depending on formulation.

At Verified Peptides, we want to note a genuine historical continuity worth highlighting directly: Triptorelin was developed in the laboratory of Andrew Schally at Tulane University, the same researcher whose earlier work (alongside Roger Guillemin) elucidating native GnRH's structure contributed to their shared 1977 Nobel Prize in Physiology or Medicine. Triptorelin was patented in 1975 and approved for medical use in several countries starting in 1986, with FDA approval following in 2000 (as Trelstar Depot, for advanced prostate cancer). It is now marketed under numerous brand names across different markets and formulations, including Decapeptyl, Diphereline, Gonapeptyl, Trelstar, Triptodur (a 6-month extended-release formulation), and Salvacyl, and appears on the World Health Organization's Model List of Essential Medicines.

Chemically, Triptorelin has molecular formula C64H82N18O13, molecular weight approximately 1311.47 g/mol, CAS number 57773-63-4, PubChem CID 25074470.

Triptorelin is formulated and sold as either the pamoate (embonate) salt or the acetate salt, depending on the specific product and depot delivery system — the pamoate salt's low aqueous solubility is specifically exploited in depot formulations to achieve slow, sustained release from an intramuscular injection site over weeks to months, while the acetate salt is more commonly used in shorter-acting or daily-injection formulations. Both salt forms deliver the identical active triptorelin peptide.

At Verified Peptides, we think Triptorelin has one of the most extensive and rigorous evidence bases in this catalog, consistent with its status as a long-approved, WHO Essential Medicine with decades of clinical use. A real Phase III, open-label, multicenter study (Perachino et al., 2009, cited under PMID 19888782, published as 'Triptorelin 6-month formulation in the management of patients with locally advanced and metastatic prostate cancer') tested a 6-month depot formulation (two consecutive 22.5 mg intramuscular injections 24 weeks apart) in 120 patients with advanced prostate cancer, reporting castrate serum testosterone levels in 97.5% of patients by day 29, with 93.0% maintaining castration through months 2-12, and 98.3% showing absent LH stimulation response after the second injection. The most common adverse event was hot flushes (71.7% of patients), with no patients withdrawing due to adverse events.

We want to note that this level of evidence — multicenter Phase III trials with clearly defined, objective biochemical endpoints (serum testosterone level relative to a defined castration threshold), long-term follow-up, and formal regulatory review across multiple countries and decades — represents a genuinely different evidentiary tier from the cosmetic peptides profiled earlier in this phase, where evidence often consisted of a single small study or, in some cases, no independently verifiable study at all. Triptorelin's approved indications now extend well beyond prostate cancer to include endometriosis, uterine fibroids, central precocious puberty, and, in some jurisdictions, hormone suppression in the context of gender-affirming care, each of which has its own separate body of supporting clinical trial literature we have not exhaustively catalogued in this profile.

At Verified Peptides, we sell research-grade Triptorelin exclusively for laboratory research, and we think this compound is a useful contrast point against thinner-evidence compounds profiled elsewhere in this catalog, illustrating what a mature, multiply-regulatory-approved peptide drug's evidence base actually looks like.

We also want to note a specific long-term monitoring finding relevant to research on this drug class generally: sustained testosterone suppression, whether from Triptorelin or related GnRH agonists, is independently associated with reduced bone mineral density over extended treatment durations, an established and clinically monitored side effect of androgen deprivation therapy broadly (not unique to Triptorelin specifically among GnRH agonists), since testosterone (and its aromatization to estrogen) plays a role in bone maintenance in men as well as women. This is a genuine, independently documented long-term safety consideration for the entire GnRH agonist drug class, distinct from the acute flare-related concerns discussed in the mechanism section above.

Triptorelin is one of several GnRH agonist analogs developed independently by different pharmaceutical research programs following the elucidation of native GnRH's structure in 1971 — other well-known analogs in this same broader drug class (some also built elsewhere in this catalog) include Leuprolide, Goserelin, Buserelin, and Histrelin, each carrying different specific amino acid substitutions and different specific approved formulations, but all sharing the same fundamental continuous-receptor-stimulation mechanism.

The development of long-acting depot formulations (1-month, 3-month, and 6-month injectable microsphere or gel formulations) represents a significant pharmaceutical engineering achievement layered on top of Triptorelin's core peptide chemistry, using biodegradable polymer microsphere technology to achieve slow, sustained peptide release over months from a single injection — a substantially more complex formulation challenge than the simple lyophilized-peptide-plus-reconstitution approach used for most research peptides in this catalog. The GnRH agonist drug class as a whole (Triptorelin, Leuprolide, Goserelin, Buserelin, Histrelin, and others) emerged from a period of intense, largely independent competitive pharmaceutical development in the late 1970s and 1980s following the structural elucidation of native GnRH, with multiple research groups converging on broadly similar substitution strategies (a D-amino acid at position 6, sometimes combined with a modified C-terminal group) to achieve enhanced receptor affinity and metabolic stability, despite being developed by separate teams.

Triptorelin's WHO Essential Medicines List status reflects its role as a globally important, cost-relevant treatment for hormone-sensitive prostate cancer in health systems worldwide, a distinction shared by comparatively few of the compounds profiled across this entire research-peptide catalog, most of which are either cosmetic ingredients or specialty pharmaceuticals with narrower usage.

At Verified Peptides, we require independent third-party HPLC purity testing and mass spectrometry identity confirmation for every batch of research-grade Triptorelin we offer, with a Certificate of Analysis (COA) available for each lot. As a 10-residue peptide with a D-amino acid substitution, pyroglutamate N-terminus, and C-terminal amidation, all of these features should be confirmed as part of identity testing, since the D-tryptophan-6 substitution specifically is what distinguishes Triptorelin from native GnRH and from other closely related GnRH agonist analogs with different substitution patterns.

We source exclusively from manufacturers operating under Good Manufacturing Practice (GMP)-aligned quality systems, and every lot is independently verified rather than accepted solely on a supplier's internal documentation. Researchers should always request and review the specific COA for the lot they receive, confirming purity percentage and molecular identity before use in any experimental protocol, and confirming which specific salt form (pamoate or acetate) a given lot represents, since the two forms are used in different formulation contexts despite delivering the same active peptide.

Lyophilized Triptorelin is stable when stored at -20°C, protected from light and moisture. At Verified Peptides, we ship lyophilized peptide with appropriate cold-chain packaging to preserve stability in transit.

Once reconstituted, solution should be stored refrigerated at 2–8°C and used within the timeframe indicated on the product's documentation, avoiding repeated freeze-thaw cycles. Researchers should note that the approved clinical depot formulations (biodegradable microsphere or gel-based sustained-release products) involve specialized pharmaceutical manufacturing processes not replicated in standard research-grade lyophilized peptide, which is intended for direct research use rather than sustained-release formulation development, and should not be assumed to have the same release kinetics as a commercial depot product even when made from the same underlying peptide.