In vitro
This study investigated the metabolic fate of alexamorelin — a synthetic peptide growth hormone secretagogue (GHS) with potential performance-enhancing properties — to identify biomarkers useful for doping control. Researchers used in silico metabolite prediction software (GLORYx) alongside in vitro incubations with pooled human hepatocytes from 10 donors, analyzing samples via liquid chromatography–high-resolution tandem mass spectrometry (LC-HRMS/MS). GLORYx predicted 21 possible single-reaction metabolites, with N-acetylation ranked highest in probability (98%), and other transformations such as hydroxylation, N-oxidation, and glucuronidation predicted at lower probabilities. However, after 3 hours of hepatocyte incubation, only one metabolite was experimentally detected: examorelin (hexarelin), produced by carboxypeptidase-mediated cleavage of the C-terminal alanine residue. The parent compound decreased approximately 150-fold over the incubation period, indicating rapid and extensive hepatic metabolism. A key limitation is that examorelin is itself a commercially available GHS compound, meaning it cannot serve as a specific biomarker for alexamorelin use. The authors conclude that direct detection of alexamorelin itself remains the most reliable strategy for confirming its consumption in anti-doping contexts. This study was conducted entirely in vitro and does not involve human subjects or animal models.
Journal of analytical toxicology · Jul 2025DOI ↗ In vitro
This study used all-atom molecular dynamics (MD) simulations, complemented by Fourier transform infrared (FTIR) spectroscopy, to investigate how two permeability enhancers (PEs) — sodium caprate and SNAC (sodium N-[8-(2-hydroxybenzoyl)amino]caprylate) — interact with four peptide drugs (octreotide, hexarelin, degarelix, and insulin) in the presence of taurocholate, an intestinal bile salt. The simulations revealed that the two PEs had distinct, peptide-dependent effects: they tended to promote release of more hydrophobic peptides while inhibiting release of more water-soluble ones. At lower peptide concentrations, peptide–peptide interactions decreased while interactions with PEs and taurocholate increased. Introducing all components together produced dynamic mixed aggregates with reduced peptide–peptide hydrogen bonding compared to peptide-only systems. FTIR analysis of insulin showed that SNAC increased β-sheet formation, while sodium caprate favored α-helical and random-coil structures. The authors suggest these molecular-level insights could guide the rational design of PE-based oral peptide formulations. Key limitations include the exclusive use of computational and in vitro/spectroscopic methods, with no cell-based, animal, or human data reported.
Nanoscale · Dec 2023DOI ↗ In vitro
This study investigated whether two growth hormone secretagogues (GHSs) — hexarelin and JMV2894 — could protect neural cells from oxidative stress in the context of amyotrophic lateral sclerosis (ALS). The researchers used human neuroblastoma cells (SH-SY5Y) engineered to express the SOD1-G93A mutant protein, a model relevant to familial ALS. Cells were exposed to hydrogen peroxide (H₂O₂) to simulate oxidative stress, with or without GHS co-treatment. The study found that both hexarelin and JMV2894 appeared to protect cells from H₂O₂-induced cytotoxicity by activating molecular pathways associated with the regulation of apoptosis and cell survival. The authors suggest these compounds may have antioxidant and neuroprotective properties worth exploring for ALS therapy. Key limitations include that this is a cell-based (in vitro) study only, using a cancer-derived cell line rather than primary motor neurons, and no animal or human data were generated. The authors themselves acknowledge the need for further work to clarify mechanisms and develop improved GHS candidates before any translational conclusions can be drawn.
International journal of molecular sciences · Jan 2023DOI ↗