Lecirelin

At Verified Peptides, we want to note an important distinction upfront: Lecirelin is not part of Khavinson's bioregulator peptide family and shares no research lineage with the several Khavinson-associated compounds built elsewhere in this Phase 4 batch (Glandokort, Vilon, Livagen, Cardiogen, Chonluten, Thymogen, Crystagen). It is a synthetic gonadotropin-releasing hormone (GnRH) agonist — a modified analog of the naturally occurring 10-residue hypothalamic hormone GnRH, engineered with amino acid substitutions and a modified C-terminus for enhanced potency and resistance to enzymatic degradation compared to native GnRH.

Lecirelin's full structure is pGlu-His-Trp-Ser-Tyr-D-Gly(tBu)-Leu-Arg-Pro-NHEt: molecular formula C59H84N16O12, molecular weight approximately 1,209.42 g/mol, CAS number 61012-19-9, PubChem CID 66577115. It is formulated and marketed as the acetate salt.

What distinguishes Lecirelin most clearly from the majority of compounds in this catalog is its regulatory status: it is an actually approved veterinary pharmaceutical, marketed under the brand names Dalmarelin, Ovucron, and Reproreline, used in veterinary medicine across Europe and Israel since approximately 2000, primarily in cattle. This gives Lecirelin a genuine, real-world regulatory and clinical-use history that is considerably more substantial than most other compounds built in this phase, though it is important to note this approval is specifically veterinary, not for human use, in any jurisdiction.

Natural GnRH itself, discovered and characterized in the early 1970s (work that contributed to a Nobel Prize in Physiology or Medicine in 1977 for Andrew Schally and Roger Guillemin), is a decapeptide released in pulsatile fashion from the hypothalamus, governing the entire reproductive endocrine axis in essentially all vertebrate species. Because native GnRH has a very short plasma half-life (on the order of minutes) due to rapid enzymatic degradation, a large family of chemically modified GnRH analogs has been developed since the 1970s and 1980s to extend duration of action and increase receptor binding potency — Lecirelin is one member of this broader analog family, engineered specifically for veterinary reproductive applications.

At Verified Peptides, we think Lecirelin's evidence base is a genuine outlier in this catalog, in a positive sense: unlike the majority of compounds built in this phase, Lecirelin has real, adequately powered veterinary clinical trial data. A randomized study (Rizzo et al., Animal Reproduction Science, 2011, PMID 21571459) enrolled 220 Friesian dairy cows with follicular cysts across four groups — epidural lecirelin (50 μg), intramuscular lecirelin (50 μg), and two untreated control groups — finding that epidural administration produced significantly higher estrus induction and pregnancy rates than intramuscular administration, positioning epidural delivery as a potentially superior route for treatment-resistant cases.

The comparative Theriogenology study described above (PMID 25890780) adds further, genuinely useful pharmacodynamic detail, directly comparing Lecirelin's LH/progesterone response profile against two other approved GnRH agonists (gonadorelin and buserelin) in the same species. This kind of direct, same-study, multi-compound comparison is something we were able to establish for very few other peptides in this entire Phase 4 batch.

We want to be equally clear about the boundaries of this evidence: all of Lecirelin's substantial clinical trial data is in cattle (and to a lesser extent other veterinary species), supporting its actual veterinary drug approval — it has not been studied in, or approved for, humans, and no human clinical trial exists or would be expected given its exclusively veterinary regulatory pathway. Researchers should not extrapolate cattle reproductive endocrinology findings directly to human GnRH-axis research without independently establishing relevance, even though the underlying GnRH-receptor biology is broadly conserved across mammalian species.

At Verified Peptides, we sell research-grade Lecirelin exclusively for laboratory research. Its veterinary approval and genuine clinical trial base make it one of the more concretely evidenced compounds in this catalog, within the specific, bounded context of veterinary reproductive endocrinology.

Lecirelin is structurally and functionally part of a well-established family of GnRH agonist drugs that includes gonadorelin (unmodified native-sequence GnRH), buserelin, leuprolide, nafarelin, and goserelin — some of which are approved human pharmaceuticals used for conditions such as prostate cancer, endometriosis, and fertility treatment, while Lecirelin itself has been developed and approved exclusively for veterinary use. This makes Lecirelin an interesting case of a drug class with substantial human pharmaceutical precedent, where this specific analog's own development and approval pathway went in a veterinary rather than human direction.

Lecirelin's route-of-administration research is genuinely more developed than for most compounds in this catalog: the epidural-versus-intramuscular comparison study found a meaningful difference in outcomes based on delivery route alone, using the identical dose (50 μg) — a finding relevant to researchers interested in how administration route can influence a peptide hormone's local versus systemic pharmacodynamic effects, independent of the compound's inherent potency.

Because Lecirelin is dosed and studied in food-producing animals (dairy and beef cattle), its use is also subject to veterinary drug residue and withdrawal-period regulations in jurisdictions where it is approved — a regulatory consideration that is largely irrelevant to research-only compounds elsewhere in this catalog but reflects Lecirelin's status as a genuine agricultural/veterinary pharmaceutical product, not merely a research chemical. Regulatory bodies overseeing veterinary drug residues, such as the European Medicines Agency's Committee for Veterinary Medicinal Products, have specifically evaluated Lecirelin's maximum residue limits in food-producing species — a level of formal regulatory scrutiny that essentially no other compound in this entire Phase 4 batch has undergone, since none of the others are approved food-animal pharmaceuticals.

Cystic ovarian disease, the primary condition Lecirelin is used to treat in dairy cattle, is a genuinely significant cause of reproductive-performance loss in commercial dairy operations, contributing to extended calving intervals and reduced milk-production efficiency when left untreated — providing real economic context for why a dedicated GnRH-agonist veterinary drug market exists for this specific indication, distinct from the human-health-driven development pathway behind most other GnRH agonists.

At Verified Peptides, we require independent third-party HPLC purity testing and mass spectrometry identity confirmation for every batch of research-grade Lecirelin we offer, with a Certificate of Analysis (COA) available for each lot. As a synthetic peptide with defined, well-characterized chemistry and an established veterinary pharmaceutical manufacturing history, Lecirelin can be synthesized and verified to high purity using standard peptide-synthesis and analytical methods.

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.

Lyophilized Lecirelin is stable when stored at -20°C, protected from light and moisture, and researchers can generally expect the unreconstituted peptide to maintain integrity over an extended period under these conditions. At Verified Peptides, we ship lyophilized peptide with appropriate cold-chain packaging to preserve stability in transit.

Once reconstituted with bacteriostatic water or another appropriate sterile diluent, Lecirelin solution should be stored refrigerated at 2–8°C and used within the timeframe indicated on the product's documentation. As with other peptides in this catalog, reconstituted solutions are generally less stable than the lyophilized form and are more susceptible to degradation and microbial contamination with repeated freeze-thaw cycling.

Researchers should avoid repeated freeze-thaw cycles of reconstituted material and should follow the specific storage guidance provided with each lot's documentation to preserve sample validity for research use.