Tag: MONOGRAPH

  • Adropin

    Secreted peptide hormone encoded by the Energy Homeostasis Associated (ENHO) gene with endothelial-protective, metabolic-regulatory, and neuroprotective activity

    A 76-amino-acid secreted peptide discovered in 2008 by Kumar et al. through liver transcriptomic profiling of melanocortin-3 receptor-deficient mice, encoded by the Energy Homeostasis Associated (Enho) gene, and subsequently characterized as a hepatokine and neuropeptide with roles in endothelial nitric oxide synthase upregulation, glucose and lipid homeostasis, insulin sensitization, neuroprotection in experimental ischemic stroke, and anti-atherosclerotic signaling through the orphan G protein-coupled receptor GPR19 and vascular endothelial growth factor receptor 2.

    Abstract

    Adropin is a 76-amino-acid secreted peptide encoded by the Energy Homeostasis Associated (Enho) gene, first identified in 2008 by Kumar et al. (Cell Metabolism) through microarray profiling of liver gene expression in melanocortin-3 receptor knockout (Mc3r-/-) mice on a C57BL/6J background [1]. The name derives from the Latin aduro (to set fire to) and pinquis (fat or greasy), reflecting the original observation that hepatic Enho expression is acutely upregulated by short-term high-fat feeding and suppressed in states of diet-induced obesity and prolonged caloric excess. The biologically active secreted domain spans amino acids 34 through 76, with residues 1 through 33 constituting a signal peptide that directs membrane anchoring and extracellular release. Human, mouse, and rat adropin amino acid sequences are 100 percent identical, a degree of conservation unusual among metabolic peptides and suggestive of strong functional constraint across mammalian species. The mature peptide has a molecular weight of approximately 4,499 daltons and functions both as a soluble circulating factor and as a membrane-bound protein facilitating intercellular communication through the Notch signaling pathway in the central nervous system. The biological effects of adropin are mediated principally through two receptor systems: the orphan G protein-coupled receptor 19 (GPR19), which couples to downstream MAPK and Akt signaling cascades in cardiomyocytes and other cell types; and vascular endothelial growth factor receptor 2 (VEGFR2), through which adropin upregulates endothelial nitric oxide synthase (eNOS) expression via the PI3K-Akt and ERK1/2 pathways to promote nitric oxide release, endothelial cell proliferation, migration, and capillary tube formation. Lovren et al. (2010) demonstrated in Circulation that adropin-treated human umbilical vein endothelial cells exhibited enhanced proliferation, migration, and tube formation with reduced permeability and tumor necrosis factor-induced apoptosis [2]. In the original Kumar et al. characterization, transgenic overexpression or systemic adropin treatment in diet-induced obese mice attenuated hepatosteatosis and insulin resistance independently of effects on adiposity or food intake, with adropin regulating expression of hepatic lipogenic genes (fatty acid synthase, stearoyl-CoA desaturase 1) and adipose tissue peroxisome proliferator-activated receptor gamma [1]. Preclinical pharmacology has expanded substantially beyond metabolic endpoints: in experimental ischemic stroke models, synthetic adropin administered intravenously at 900 to 2,700 nmol/kg at the onset of or up to 3 hours after permanent middle cerebral artery occlusion dose-dependently reduced infarct size, blood-brain barrier disruption, tight junction protein degradation, matrix metalloproteinase-9 activity, oxidative stress, and neutrophil infiltration through an eNOS-dependent mechanism, as adropin therapy failed to confer neuroprotection in eNOS-deficient mice [3, 4]. Additional preclinical work has demonstrated anti-atherosclerotic activity through suppression of monocyte-endothelial cell adhesion and smooth muscle cell proliferation [5], preservation of the blood-brain barrier after intracerebral hemorrhage through a Notch1/Hes1 pathway [6], and restoration of cardiac glucose oxidation in pre-diabetic obese mice through modulation of the mitochondrial acetyltransferase GCN5L1 [7]. Clinical studies in humans are predominantly observational: serum adropin levels are consistently and significantly lower in patients with coronary artery disease, acute myocardial infarction, metabolic syndrome, type 2 diabetes mellitus, polycystic ovary syndrome, and obstructive sleep apnea compared to healthy controls, with inverse correlations between adropin concentration and disease severity scores including the SYNTAX score for coronary atherosclerotic burden [8, 9, 10]. A meta-analysis by Zheng et al. (2019) encompassing 7 case-control studies with 525 coronary artery disease patients and 420 controls confirmed the consistent inverse association [8]. No human interventional trials of exogenous adropin administration have been published as of the most recent monograph revision. The compound is available as a synthetic research peptide from multiple suppliers (Phoenix Pharmaceuticals, Bachem, Creative Peptides, GenScript) typically as adropin (34-76), the biologically active fragment, at greater than 95 percent purity by HPLC. This monograph reviews the discovery and gene characterization; the amino acid sequence, structure, and synthesis; the dual-receptor molecular pharmacology through GPR19 and VEGFR2-eNOS; the tissue distribution and nutritional regulation of Enho expression; the preclinical pharmacology across metabolic, cardiovascular, and neurological models; the clinical observational evidence base; sourcing and quality verification; reconstitution and handling; stack interactions; adverse events and safety considerations; and a comparative assessment of five metabolic-regulatory peptide candidates (irisin, FGF21, GDF15, apelin, MOTS-c) against adropin on five competency standards.

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  • Cardiogen

    Synthetic cardioprotective tetrapeptide bioregulator with epigenetic gene-regulatory and anti-apoptotic activity targeting cardiomyocytes

    A synthetic tetrapeptide (H-Ala-Glu-Asp-Arg-OH; AEDR) developed at the Saint Petersburg Institute of Bioregulation and Gerontology as an ultrashort peptide bioregulator with cardioprotective, anti-apoptotic, and epigenetic chromatin-regulatory activity targeting cardiomyocytes, cardiac fibroblasts, and myocardial gene expression programs.

    Abstract

    Cardiogen (H-Ala-Glu-Asp-Arg-OH; AEDR tetrapeptide; molecular formula C18H31N7O9; molecular weight 489.48 g/mol) is a synthetic tetrapeptide bioregulator developed by Vladimir Khavinson and colleagues at the Saint Petersburg Institute of Bioregulation and Gerontology as the cardiac-specific member of the Khavinson ultrashort peptide bioregulator family [1, 2]. The compound belongs to a class of synthetic two-to-seven-residue peptide sequences modeled on tissue-specific peptide fragments isolated from mammalian organ extracts, and is designated as the cardiovascular system bioregulator within this peptide family. Cardiogen shares the Ala-Glu-Asp tripeptide core with the cortical bioregulator Cortagen (Ala-Glu-Asp-Pro) and the pineal bioregulator Epithalon (Ala-Glu-Asp-Gly), differing from these compounds by the fourth-position arginine residue, a single amino acid substitution that determines cardiac tissue specificity within the Khavinson classification system [3, 4]. The principal molecular mechanism of Cardiogen, characterized through molecular modeling, cell culture, and organotypic myocardial tissue studies, is epigenetic regulation of gene expression through direct interaction of the tetrapeptide with double-stranded DNA in gene promoter regions and with histone proteins (H1, H2B, H3, H4), producing chromatin decondensation and reactivation of transcriptional programs in cardiac cells [5, 6, 7]. The cardioprotective activity, characterized in organotypic myocardial tissue cultures, embryonic fibroblast cultures, and coronary artery ligation animal models, includes stimulation of cardiomyocyte proliferation with concurrent suppression of cardiomyocyte apoptosis through p53 protein downregulation, upregulation of cytoskeletal proteins (actin, vimentin, tubulin) by up to five-fold and nuclear matrix proteins (lamin A, lamin C) by up to 2.5-fold relative to control, preservation of myocardial glycogen stores and cellular energy production structures under ischemic conditions, and a reported threefold reduction in mortality following experimental coronary artery ligation in treated versus control groups [8, 9, 10, 11]. In a separate line of investigation, Cardiogen demonstrated tumor-modifying activity against transplanted M-1 sarcoma in senescent rats, with dose-dependent inhibition of tumor growth mediated by hemorrhagic necrosis and stimulation of tumor cell apoptosis through a vascular mechanism rather than direct cytostatic effect [12]. The compound has been characterized in the context of the senescence-associated secretory phenotype of cardiovascular system cells and inflammaging, with evidence that the AEDR tetrapeptide regulates molecules involved in the inflammatory pathways contributing to age-related cardiovascular decline [13]. No formal pharmacokinetic studies have been published for Cardiogen as the isolated synthetic AEDR tetrapeptide. As a linear tetrapeptide with unprotected termini, the compound is expected to undergo rapid proteolytic degradation by aminopeptidases and carboxypeptidases in plasma and gastrointestinal fluid; however, molecular modeling studies have demonstrated that ultrashort peptides are substrates of the proton-coupled oligopeptide transporter (PEPT1/PEPT2) family carriers, supporting intestinal absorption and cellular uptake through active transport mechanisms [14, 15]. No human clinical trials have been published. The compound is not approved by the United States Food and Drug Administration, the European Medicines Agency, or any major Western regulatory authority. Cardiogen is registered in the Russian Federation as a biologically active additive and is commercially available there in capsule and sublingual formulations. It is supplied internationally as a research-grade lyophilized peptide by multiple peptide synthesis vendors at greater than 95 percent purity by high-performance liquid chromatography. This monograph reviews the chemistry, synthesis, and structural characterization of Cardiogen; the discovery and development history within the Khavinson bioregulatory peptide program; the molecular pharmacology including peptide-DNA binding, histone interaction, and cardiac gene expression modulation; the pharmacokinetic considerations for ultrashort peptides; the preclinical pharmacology across cardiac, inflammatory, and aging cell models; the clinical evidence base (absent); sourcing and quality verification; reconstitution and handling; stack interactions and combinations; adverse events and safety signal; and a comparative assessment of five cardioprotective or cardiac-repair peptide candidates (Vesugen, Thymosin beta-4, BPC-157, Cortagen, GHK-Cu) against Cardiogen on five competency standards.

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  • Crystagen

    Synthetic immunomodulatory tripeptide bioregulator of thymic origin with epigenetic gene-regulatory and cytoprotective activity

    A synthetic tripeptide (L-Glu-L-Asp-L-Pro; EDP) derived from structural analysis of the thymic polypeptide complex Thymalin, developed at the Saint Petersburg Institute of Bioregulation and Gerontology as an ultrashort peptide bioregulator with immunomodulatory, cytoprotective, and epigenetic chromatin-regulatory activity targeting thymic epithelial cells, T-lymphocyte subpopulations, and heat-shock protein gene expression.

    Abstract

    Crystagen (L-glutamyl-L-aspartyl-L-proline; EDP tripeptide; molecular formula C14H21N3O8; molecular weight 359.33 g/mol) is a synthetic tripeptide bioregulator developed by Vladimir Khavinson and colleagues at the Saint Petersburg Institute of Bioregulation and Gerontology as one of the principal short-peptide bioactive components of Thymalin, a bovine thymus polypeptide extract approved in the Soviet Union and Russian Federation since 1982 for clinical immunocorrection [1, 2]. The compound belongs to the Khavinson class of ultrashort (two to seven residue) peptide bioregulators, a family of synthetic sequences modeled on tissue-specific peptide fragments isolated from organ extracts by acid-pepsin hydrolysis and ultrafiltration, and is designated as the thymic immune system bioregulator within this peptide family. Crystagen shares the Glu-Asp dipeptide core with the bronchial bioregulator Chonluten (Glu-Asp-Gly) and the cortical bioregulator Cortagen (Ala-Glu-Asp-Pro), differing from these compounds by the third-position proline residue and the absence of the N-terminal alanine extension, respectively; the single amino acid substitution at the third position determines tissue specificity within the Khavinson classification [3, 4]. In the Khavinson laboratory internal code system, the compound is designated T-36 [5]. The principal molecular mechanism of Crystagen, characterized through molecular modeling, cell culture, and organotypic tissue studies, is epigenetic regulation of gene expression through direct interaction of the tripeptide with double-stranded DNA in gene promoter regions and with histone proteins (H1, H2B, H3, H4), producing chromatin decondensation and reactivation of age-repressed transcriptional programs in immune cells [6, 7, 8]. The immunomodulatory activity, characterized in thymic cell cultures, splenic organotypic cultures, and in the THP-1 monocyte/macrophage cell line, includes stimulation of T-lymphocyte differentiation with increased CD3+ and CD4+ cell populations, normalization of the CD4+/CD8+ ratio, activation of B-cell immunity in the spleen, suppression of thymocyte apoptosis through p53 downregulation and Ki-67 upregulation, enhancement of normal lymphocyte proliferation with concurrent inhibition of K-562 tumor cell proliferation, and modulation of cytokine expression including interleukin-6 normalization [9, 10, 11, 12]. The cytoprotective profile includes a pronounced upregulation of heat-shock protein gene HSPA1A (encoding HSP-70), with expression increasing approximately 2.2-fold relative to baseline in a study of highly trained female artistic gymnasts receiving Crystagen in combination with other peptide bioregulators, an effect accompanied by reduced incidence of acute respiratory infections during epidemic conditions [13, 14]. In a clinical observational study of elderly patients, oral Crystagen administration normalized immunogram parameters in 82 percent of treated individuals compared to 56 percent in the control group [15]. The geroprotective context for Crystagen derives from the parent compound Thymalin, which in a 266-patient, 6-to-8-year prospective clinical study conducted at the Saint Petersburg Institute of Bioregulation and Gerontology and the Institute of Gerontology of the Ukrainian Academy of Medical Sciences produced a 2.0-to-2.1-fold reduction in mortality rate relative to control, and a 4.1-fold mortality reduction when combined with the pineal peptide Epithalamin [16]. No formal pharmacokinetic studies have been published for Crystagen as the isolated synthetic EDP tripeptide. As a linear tripeptide with unprotected termini, the compound is expected to undergo rapid proteolytic degradation by aminopeptidases and carboxypeptidases in plasma and gastrointestinal fluid; however, molecular modeling studies have demonstrated that ultrashort peptides including EDP are substrates of the proton-coupled oligopeptide transporter (POT) family carriers PEPT1 and PEPT2, supporting intestinal absorption and cellular uptake through active transport mechanisms [17, 18]. The compound is not approved by the United States Food and Drug Administration, the European Medicines Agency, or any major Western regulatory authority. It is not registered as a pharmaceutical product outside the Russian Federation. Crystagen is commercially available in Russia as a dietary supplement in capsule and sublingual formulations and is supplied internationally as a research-grade lyophilized peptide by multiple peptide synthesis vendors at greater than 95 percent purity by high-performance liquid chromatography. This monograph reviews the chemistry, synthesis, and structural characterization of Crystagen; the discovery and development history within the Khavinson bioregulatory peptide program; the molecular pharmacology including peptide-DNA binding, histone interaction, and gene expression modulation; the pharmacokinetic considerations for ultrashort peptides; the preclinical pharmacology across immune, inflammatory, and aging cell models; the clinical evidence base (observational); sourcing and quality verification; reconstitution and handling; stack interactions and combinations; adverse events and safety signal; and a comparative assessment of five immunomodulatory peptide candidates (Thymogen, Vilon, Thymosin alpha-1, Thymulin, Epithalon) against Crystagen on five competency standards.

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    FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

  • Histrelin

    Synthetic gonadotropin-releasing hormone superagonist nonapeptide with sustained pituitary-gonadal axis suppression through GnRH receptor desensitization and downregulation

    A synthetic nonapeptide analog of endogenous gonadotropin-releasing hormone bearing a D-histidine(N-benzyl) substitution at position 6 and an ethylamide C-terminal modification, conferring approximately 100- to 200-fold greater potency than native GnRH and marked resistance to enzymatic degradation, developed at Ortho Pharmaceutical in the early 1980s and now FDA-approved as a once-yearly subcutaneous hydrogel implant for advanced prostate cancer (Vantas, approved 2004, discontinued 2020) and central precocious puberty (Supprelin LA, approved 2007), distinguished from other GnRH agonists by the highest binding affinity in the clinical class and the longest approved dosing interval achieved through a diffusion-controlled hydrogel polymer reservoir delivery system.

    Abstract

    Histrelin (pGlu-His-Trp-Ser-Tyr-D-His(Bzl)-Leu-Arg-Pro-NHEt; CAS 76712-82-8, free base; molecular formula C66H86N18O12; molecular weight 1323.53) is a synthetic nonapeptide analog of the hypothalamic decapeptide gonadotropin-releasing hormone (GnRH, also designated luteinizing hormone-releasing hormone, LHRH) distinguished from other members of the clinical GnRH agonist class by exceptionally high receptor binding affinity and by a unique formulation as a once-yearly subcutaneous hydrogel polymer implant [1, 2]. The compound incorporates two structural modifications to native GnRH that collectively confer superagonist potency and metabolic stability: replacement of glycine at position 6 with D-histidine bearing an N-benzyl substituent on the imidazole ring, which eliminates the principal endopeptidase cleavage site and introduces a bulky aromatic moiety favorable to hydrophobic interaction with the GnRH receptor transmembrane domain; and replacement of the C-terminal glycinamide (position 10) with an ethylamide, which further resists carboxypeptidase degradation [3, 4]. The resulting peptide binds the type I GnRH receptor with affinity approximately 100- to 200-fold greater than native GnRH and produces the characteristic biphasic pharmacological response common to all GnRH superagonists [5, 6]. Acute administration stimulates pituitary gonadotroph secretion of luteinizing hormone and follicle-stimulating hormone, producing transient elevations in gonadal steroid output (the “flare” phase, lasting 7 to 14 days). Chronic continuous administration produces homologous desensitization of the GnRH receptor through receptor internalization, uncoupling from Gq/11-phospholipase C signaling, and transcriptional downregulation of GnRH receptor expression, resulting in profound and sustained suppression of gonadotropin secretion and a hypogonadal state equivalent to surgical castration in both sexes [5, 6, 7]. Histrelin was initially developed at Ortho Pharmaceutical Corporation (a Johnson and Johnson subsidiary) in the early 1980s and studied in daily subcutaneous injection formulations for central precocious puberty, prostate cancer, and endometriosis [8, 9]. The compound was subsequently reformulated by Roberts Laboratories (later acquired by Shire Pharmaceuticals, then Endo Pharmaceuticals) into a diffusion-controlled hydrogel polymer reservoir subcutaneous implant delivering approximately 65 micrograms of histrelin acetate per day over 12 months [10, 11]. This implant technology produced two FDA-approved products: Vantas (50 mg histrelin acetate implant for palliative treatment of advanced prostate cancer, approved October 2004) and Supprelin LA (50 mg histrelin acetate implant for central precocious puberty, approved May 2007) [12, 13]. Vantas was discontinued in 2020 owing to manufacturing quality issues at the production facility; Supprelin LA remains commercially available. Pharmacokinetics of the implant formulation are characterized by sustained zero-order drug release producing median steady-state serum histrelin concentrations of approximately 0.2 to 0.4 ng/mL, with a terminal elimination half-life of the released peptide of approximately 4 hours, 92 percent subcutaneous bioavailability, and approximately 70 percent plasma protein binding [10, 14]. Metabolism is hepatic through peptidase-mediated degradation. The adverse-event profile is dominated by the pharmacological consequences of gonadal steroid suppression: hot flashes, reduced libido, erectile dysfunction or amenorrhea, and long-term bone mineral density reduction. Implant site reactions (bruising, pain, erythema) occur in approximately 50 percent of recipients. The initial flare phase carries specific risk in metastatic prostate cancer, which is mitigated by co-administration of an antiandrogen during the first 2 to 4 weeks of therapy. Postmarketing surveillance has identified rare but serious adverse events including pseudotumor cerebri, seizures, psychiatric symptoms (emotional lability, depression, suicidal ideation), and severe cutaneous adverse reactions. This monograph reviews the chemistry and synthesis, the biphasic GnRH receptor pharmacology, the comprehensive human pharmacokinetic record, the clinical evidence base across prostate cancer, central precocious puberty, endometriosis, and gender-affirming therapy indications, sourcing and quality verification, reconstitution and handling, stack interactions, adverse-event signal, and a comparative assessment of five GnRH agonist candidates against histrelin on five competency standards.

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  • Spexin

    Endogenous neuropeptide agonist of galanin receptor type 2 (GALR2) and galanin receptor type 3 (GALR3)

    A 14-amino-acid C-terminally amidated neuropeptide of the galanin/kisspeptin/spexin superfamily, identified by bioinformatic hidden Markov model screening of the human proteome in 2007 and subsequently characterized as a satiety factor, metabolic regulator, anxiolytic peptide, and antinociceptive agent operating through selective activation of galanin receptor subtypes 2 and 3.

    Abstract

    Spexin (SPX), also designated neuropeptide Q (NPQ), is a 14-amino-acid peptide hormone encoded by the C12orf39 gene on human chromosome 12 and processed from a 116-amino-acid prepropeptide by dibasic cleavage and C-terminal alpha-amidation [1, 2]. The mature human sequence (NWTPQAMLYLKGAQ-NH2) is perfectly conserved across all mammalian species examined and differs by only one to two residues from teleost orthologs, placing spexin among the most evolutionarily conserved vertebrate peptide hormones [3]. First identified in 2007 by Mirabeau and colleagues through a hidden Markov model algorithm designed to detect novel secreted peptide hormones in the human genome, and first confirmed biochemically in murine esophageal and gastric tissue [1], spexin was subsequently shown to activate galanin receptor type 2 (GALR2) and galanin receptor type 3 (GALR3) with nanomolar potency (EC50 values of approximately 45.7 and 112.2 nM respectively) while showing no measurable activity at galanin receptor type 1 (GALR1) [4, 5]. This receptor selectivity profile distinguishes spexin from galanin itself, which activates all three galanin receptor subtypes, and establishes spexin as a naturally occurring GALR2/GALR3-selective agonist. The peptide is expressed broadly across central and peripheral tissues including the hypothalamus, hippocampus, amygdala, adipose tissue, liver, gastrointestinal tract, pancreas, kidney, heart, ovary, and testis [6, 7]. Functionally, spexin has been characterized as a satiety factor that suppresses food intake in goldfish, zebrafish, and mice through hypothalamic regulation of orexigenic (neuropeptide Y, agouti-related protein) and anorexigenic (proopiomelanocortin, cocaine- and amphetamine-regulated transcript) neuropeptides [8, 9, 10]. In adipose tissue, spexin inhibits long-chain fatty acid uptake into adipocytes and promotes weight loss in diet-induced obese rodents [11]. Circulating spexin concentrations are significantly reduced in human obesity, type 1 diabetes, type 2 diabetes, metabolic syndrome, and polycystic ovary syndrome, establishing the peptide as a candidate biomarker for metabolic dysregulation [12, 13, 14]. Beyond metabolic regulation, spexin-based GALR2-selective agonists produce anxiolytic effects in murine behavioral models [5], and the metabolically stabilized analog LIT-01-144 produces potent non-opioid peripheral antinociception in persistent inflammatory pain through GALR2 activation [15]. In reproductive physiology, spexin inhibits gonadotropin (LH and FSH) synthesis and secretion in multiple vertebrate species and negatively regulates ovarian steroidogenesis [16, 17]. No human clinical trials of exogenous spexin administration have been reported; the compound remains in the preclinical and biomarker research phase. This monograph reviews the chemistry, gene structure, and peptide processing of spexin; the receptor pharmacology and signal transduction through GALR2 and GALR3; the preclinical pharmacology across metabolic, appetite, nociceptive, anxiolytic, reproductive, and cardiovascular domains; the human biomarker and associative clinical evidence; sourcing and handling considerations for research-grade material; analog development for metabolic stability; and a comparative assessment against five related peptide or receptor-targeted candidates on five competency standards.

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  • Methoxyflurane

    Plain-language summaryIntrigue 65 / 100

    Methoxyflurane is an early halogenated ether that had a remarkable second life. As a general anesthetic (Penthrane, 1962) it was withdrawn in 1974 after dose-dependent nephrotoxicity was traced to intrarenal defluorination producing high plasma fluoride that blocks ascending-limb chloride transport. Forty years later it returned in a low-dose hand-held inhaler format (Penthrox, the green whistle) for procedural analgesia, approved in Australia and re-approved in the EU and UK in 2018. The 3 mL inhaler dose for fracture reduction or dressing changes delivers fluoride exposures orders of magnitude below the historical nephrotoxic threshold. Mechanism includes the standard volatile anesthetic profile plus pronounced TRPA1 modulation that contributes to the analgesia. A genuinely novel sub-anesthetic application of an old molecule. Not stocked by Kodiac. This monograph is provided for research and educational reference.

    Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.

    Halogenated ether volatile general anesthetic and analgesic

    An early halogenated ether withdrawn for nephrotoxicity but reintroduced in low-dose hand-held inhaler format (Penthrox) for procedural analgesia.

    Abstract

    Methoxyflurane (2,2-dichloro-1,1-difluoroethyl methyl ether; CAS 76-38-0; molecular formula C3H4Cl2F2O; molecular weight 164.97) is a halogenated methyl ethyl ether developed by Ross Terrell in the 1950s and introduced clinically by Abbott in 1962 (Penthrane). The agent was widely used as a general anesthetic through the early 1970s before reports of dose-dependent nephrotoxicity led to withdrawal as a primary anesthetic in 1974 in the United States. The mechanism of methoxyflurane nephrotoxicity is intrarenal defluorination by CYP2E1 producing inorganic fluoride at concentrations sufficient to inhibit ascending limb chloride transport (high-output renal failure with vasopressin-resistant polyuria, the classical methoxyflurane nephropathy). The threshold for clinically apparent renal injury is approximately 50 micromolar plasma fluoride and is exceeded by general anesthetic doses (MAC 0.16 percent for many hours) but not by the brief, low-dose inhaler format reintroduced as Penthrox in Australia and re-approved in the EU and UK in 2018 for procedural analgesia. The Penthrox formulation delivers approximately 3 mL methoxyflurane through a hand-held disposable inhaler (the green whistle), producing analgesia for procedural pain (extremity injuries, dressing changes, fracture reduction) at exposure levels orders of magnitude below the historical nephrotoxic threshold. The blood-gas partition coefficient is 13, the highest in the class, corresponding to slow induction and prolonged emergence; the clinical Penthrox dose is sub-anesthetic and produces only analgesia and mild sedation. Mechanism includes the standard halogenated ether profile plus pronounced TRPA1 modulation contributing to the analgesic phenotype.

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  • Pentadeca Arginate (PDA)

    Arginate salt analog of BPC-157

    A research-grade arginate salt formulation of the pentadecapeptide BPC-157 sequence, formulated for improved aqueous stability and shelf life relative to acetate-salt parent.

    Abstract

    Pentadeca Arginate (PDA; the pentadecapeptide Gly-Glu-Pro-Pro-Pro-Gly-Lys-Pro-Ala-Asp-Asp-Ala-Gly-Leu-Val formulated as the arginate salt; the underlying peptide is identical to BPC-157, CAS 137525-51-0; molecular formula C62H98N16O22 free peptide; molecular weight 1419.55 free peptide; the arginate salt adds counterions and is formulated for improved stability) is a research-grade alternative formulation of the BPC-157 pentadecapeptide that has emerged in research-grade peptide vendor catalogs in 2023 to 2024 as a stabilized analog. The pharmacological argument is that the arginate counterion improves aqueous solubility and extends shelf life of the lyophilized solid relative to acetate-salt BPC-157, which is the standard formulation; the underlying peptide sequence and pharmacology are identical, and any differences between PDA and BPC-157 in vivo are attributable to formulation rather than to a different molecule. The published preclinical record on the BPC-157 sequence is summarized in the Kodiac BPC-157 monograph (KDC-MN-002): tendon and ligament healing, vascular reorganization, gastrointestinal mucosal protection, dopaminergic system modulation, broad rodent injury-recovery activity, with the limitation that the literature is dominated by the originating Sikiric group at the University of Zagreb. PDA has no independent published preclinical record beyond the parent BPC-157 work; vendor literature emphasizes formulation stability claims rather than novel pharmacology. Investigators should not assume that PDA differs pharmacologically from BPC-157 acetate; the choice between formulations should be made on stability and handling considerations. Reconstitution and dosing follow BPC-157: bacteriostatic water for injection, refrigerated storage of reconstituted solution, parenteral administration at 250 to 500 mcg per dose. The compound is research-grade and not approved by any regulatory authority for human or veterinary use.

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  • Bradanicline

    Selective alpha-7 nicotinic acetylcholine receptor full agonist

    A quinuclidine benzofuran-2-carboxamide developed at Targacept as a selective alpha-7 nicotinic full agonist with a binding affinity of 1.4 nanomolar at the human alpha-7 receptor, advanced through Phase 2 development for cognitive impairment and negative symptoms of schizophrenia with a positive 12-week exploratory trial followed by a negative larger 24-week confirmatory trial, subsequently licensed to Anvylic Therapeutics for Tourette syndrome and other indications.

    Abstract

    Bradanicline (development codes TC-5619 and ATA-101) is a small-molecule, highly selective full agonist of the homopentameric alpha-7 subtype of the neuronal nicotinic acetylcholine receptor (alpha-7 nAChR), originated at Targacept Pharmaceuticals (Winston-Salem, North Carolina) from a quinuclidine benzofuran-2-carboxamide chemistry program in the mid-2000s and advanced through Phase 1 and Phase 2 clinical development for cognitive impairment associated with schizophrenia. The compound binds the human alpha-7 nicotinic receptor with a Ki of approximately 1.4 nanomolar, slightly higher affinity than encenicline (Ki approximately 4 nanomolar) and substantially higher affinity than tropisetron at the alpha-7 site, and exhibits functional intrinsic activity of approximately 80 to 90 percent of the acetylcholine maximum response in heterologous expression systems, placing it in the high-efficacy stratum of alpha-7 ligands as a full agonist rather than the partial-agonist class that encenicline and tropisetron occupy. The full-agonist intrinsic activity is the principal medicinal-chemistry differentiator of bradanicline within the broader quinuclidine-amide chemical class. Selectivity over alpha-4-beta-2, alpha-3-beta-4, alpha-3-beta-2, and other neuronal nicotinic subtypes is approximately 100-fold or greater. The compound was advanced through an exploratory Phase 2 trial in 185 schizophrenia patients (Lieberman et al. 2013) at 5 milligrams once daily for 12 weeks, with statistically significant improvement on the Groton Maze Learning Task and on the Scale for Assessment of Negative Symptoms compared to placebo, and a statistically significant drug effect on working memory in the tobacco-using subgroup. A larger confirmatory Phase 2 trial (Walling et al. 2016) in 477 schizophrenia outpatients across 64 sites at 5 or 50 milligrams once daily for 24 weeks did not support a benefit on negative or cognitive symptoms compared to placebo. Targacept terminated the cognitive impairment program in 2013 and the compound was subsequently licensed to Catalyst Biosciences and to Anvylic Therapeutics for Tourette syndrome and selected other neurological indications. The compound represents a useful research-clinical reference for the alpha-7 nicotinic full-agonist class and for the assessment of whether higher functional intrinsic activity at the receptor produces greater clinical benefit. Bradanicline did not produce the severe gastrointestinal toxicity that triggered the September 2015 FDA clinical hold on encenicline; the safety profile in Phase 2 was well-tolerated with no clinically noteworthy findings reported. The compound is supplied as a research-grade reagent (greater than 98 percent purity) by multiple chemical suppliers and continues to serve as a reference alpha-7 nicotinic full agonist for fundamental pharmacology research. This monograph reviews the chemistry, synthesis, and stereochemistry of bradanicline; the receptor pharmacology in detail; the human pharmacokinetic record; the indication-by-indication clinical evidence base; and a structured comparative assessment of five alpha-7 nicotinic acetylcholine receptor candidates against bradanicline on five competency standards.

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  • LL-37

    Cathelicidin-derived cationic antimicrobial and immunomodulatory peptide

    The sole human cathelicidin-derived antimicrobial peptide, a 37-residue amphipathic alpha-helical cationic peptide released from the precursor protein hCAP-18 by proteinase 3 cleavage, possessing direct broad-spectrum antimicrobial activity through membrane disruption and pleiotropic immunomodulatory functions mediated by formyl peptide receptor 2, P2X7, and toll-like receptor signaling.

    Abstract

    LL-37, the carboxy-terminal 37-residue peptide of human cationic antimicrobial protein 18 (hCAP-18), is the only cathelicidin-derived antimicrobial peptide identified in the human genome and is a central effector of innate immune defense across epithelial surfaces, wound repair, and inflammatory regulation. The peptide was first identified as FALL-39 by Gudmundsson, Agerberth, and colleagues at the Karolinska Institutet in 1996 through screening of a human bone marrow cDNA library [1], and the mature processed form was subsequently designated LL-37 on the basis of its amino-terminal leucine-leucine sequence and 37-residue length [2]. hCAP-18, the 18-kilodalton holoprotein precursor, is constitutively stored in the specific granules of neutrophils and is released and proteolytically processed by neutrophil-derived proteinase 3 at sites of infection and inflammation to yield the biologically active LL-37 fragment [3]. The peptide adopts an amphipathic alpha-helical conformation in membrane-mimetic environments and exerts direct antimicrobial activity against gram-positive and gram-negative bacteria, enveloped viruses, and fungi through electrostatic interaction with anionic microbial membranes followed by membrane permeabilization and disruption [4, 5]. Beyond direct microbicidal activity, LL-37 functions as a multifunctional immunomodulatory mediator: it signals through formyl peptide receptor 2 (FPR2/ALX) to recruit neutrophils, monocytes, and T cells [6]; it neutralizes bacterial lipopolysaccharide and prevents endotoxin-driven inflammatory cascades [7]; it promotes angiogenesis and wound re-epithelialization through epidermal growth factor receptor transactivation [8]; and it modulates adaptive immune responses through effects on dendritic cell maturation and T helper cell polarization [9]. Expression of hCAP-18/LL-37 is transcriptionally regulated by 1,25-dihydroxyvitamin D3 through a vitamin D response element in the CAMP gene promoter, a mechanism first characterized by Liu et al. (2006) in a landmark demonstration that toll-like receptor activation of human macrophages by Mycobacterium tuberculosis triggers CYP27B1-mediated conversion of 25-hydroxyvitamin D to the active 1,25-dihydroxy form, which then induces cathelicidin expression and intracellular killing of the mycobacterium [10]. This vitamin D-cathelicidin axis has become a major research focus in tuberculosis, respiratory infection, and immunodeficiency. Clinical translation of LL-37 has advanced through Phase I and Phase II trials in chronic wound healing, where topical application of synthetic LL-37 at 0.5 and 1.6 mg/mL produced healing rate constants approximately three- to six-fold greater than placebo in hard-to-heal venous leg ulcers [11], and through a Phase IIb multicenter trial of 148 patients that identified a subgroup benefit in ulcers exceeding 10 cm2 [12]. A randomized trial of recombinant LL-37 delivered via Lactococcus lactis as oral therapy against SARS-CoV-2 Omicron BA.5.1.3 demonstrated significant shortening of viral RNA negative conversion time with early intervention and acceptable safety [13]. The peptide is also implicated in the pathogenesis of rosacea, where aberrant processing of cathelicidin by kallikrein 5 serine protease generates proinflammatory LL-37 fragments in facial skin [14]; in psoriasis, where LL-37 complexed with self-DNA activates plasmacytoid dendritic cells through toll-like receptor 9 [15]; and in cancer biology, where context-dependent pro-tumorigenic and anti-tumorigenic effects have been reported across colorectal, breast, ovarian, and lung malignancies [16, 17]. Pharmacokinetically, the peptide is susceptible to rapid proteolytic degradation in serum with a half-life of minutes to hours depending on protease milieu, limiting systemic bioavailability and driving research toward local and topical delivery, protease-resistant analogs, d-amino acid substitutions, and nanoparticle encapsulation strategies [18, 19]. The compound is commercially available as a synthetic peptide at greater than 95 percent purity from multiple peptide synthesis suppliers. This monograph reviews the chemistry, structure, and processing of LL-37; the molecular pharmacology including direct antimicrobial mechanisms and immunomodulatory receptor signaling; the vitamin D transcriptional axis; preclinical pharmacology across infection, inflammation, and wound healing models; the clinical evidence base in chronic wounds, infectious disease, and dermatologic conditions; reconstitution and handling; stack interactions; adverse events and safety signals including the rosacea and psoriasis pathogenic associations; and a comparative assessment of five alternative antimicrobial and immunomodulatory peptide candidates against LL-37 on five competency standards.

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  • Pegvisomant

    PEGylated recombinant human growth hormone receptor antagonist

    A protein-engineered, PEGylated analog of human growth hormone carrying nine amino acid substitutions that confer high-affinity binding at growth hormone receptor site 1 and functional antagonism at site 2, developed as the first and only growth hormone receptor antagonist approved for the treatment of acromegaly refractory to surgery and radiation.

    Abstract

    Pegvisomant (B2036-PEG; trade name Somavert; CAS 218620-50-9) is a PEGylated recombinant human growth hormone (hGH) analogue engineered to function as a selective competitive antagonist of the growth hormone receptor (GHR), approved by the United States Food and Drug Administration in 2003 for the treatment of acromegaly in patients who have had an inadequate response to surgery, radiation therapy, or other medical therapies, or for whom these therapies are not appropriate. The compound consists of a 191-amino-acid polypeptide backbone (designated B2036) carrying nine amino acid substitutions relative to wild-type hGH: eight substitutions in the site 1 binding interface (His18Asp, His21Asn, Arg167Asn, Lys168Ala, Asp171Ser, Lys172Arg, Glu174Ser, Ile179Thr) that increase binding affinity for the first GHR molecule, and one substitution in the site 2 binding interface (Gly120Lys) that introduces a bulky lysine side chain preventing the conformational change required for functional receptor dimerization and activation of the JAK2-STAT5 signaling cascade [1, 2]. The B2036 protein is covalently conjugated with four to six polyethylene glycol (PEG) polymers of approximately 5 kDa each at lysine residues and the N-terminus, yielding a final molecular mass of approximately 42 to 52 kDa depending on PEGylation stoichiometry. PEGylation extends the plasma elimination half-life from approximately 15 minutes (unpegylated B2036) to 60 to 138 hours, reduces immunogenicity, and permits once-daily subcutaneous dosing [3, 4]. Pegvisomant was discovered in 1987 by John Kopchick and Wen Chen at the Edison Biotechnology Institute at Ohio University through transgenic mouse studies demonstrating that substitution of glycine 120 in the third alpha-helix of growth hormone with bulky amino acids abolished growth-promoting activity and created a functional antagonist of endogenous growth hormone action [1]. Sensus Drug Development Corporation licensed the technology and advanced the compound through clinical development with PEGylation applied to extend the pharmacokinetic profile. Pharmacia Corporation acquired Sensus in 2001 and was subsequently acquired by Pfizer. The FDA approved pegvisomant (Somavert) on March 26, 2003; the European Medicines Agency granted marketing authorization in November 2002 [5]. The mechanism of action is fundamentally distinct from the other medical therapies for acromegaly. Somatostatin receptor ligands (octreotide, lanreotide, pasireotide) and dopamine agonists (cabergoline) act at the pituitary level to suppress growth hormone secretion. Pegvisomant acts at the peripheral target organ level by competitively blocking GHR activation, thereby reducing hepatic production of insulin-like growth factor I (IGF-I), the principal mediator of the somatic and metabolic consequences of growth hormone excess. This peripheral mechanism renders pegvisomant effective regardless of pituitary tumor somatostatin receptor expression, GH secretory dynamics, or tumor histological subtype [2, 6]. In the pivotal Phase 3 randomized, double-blind, placebo-controlled trial reported by Trainer et al. (2000) in the New England Journal of Medicine, pegvisomant at 10, 15, and 20 mg daily subcutaneously for 12 weeks normalized serum IGF-I concentrations in 54, 81, and 89 percent of patients with acromegaly, respectively, compared to 10 percent on placebo [6]. Long-term surveillance data from the ACROSTUDY international observational registry, encompassing 2,221 patients followed for a median of 7.4 years, confirmed a favorable safety profile with IGF-I normalization rates reaching 75.4 percent at 10 years of treatment, pituitary tumor size increase in 7.1 percent by local reading, liver function abnormalities in 3.2 percent, and treatment-related adverse events leading to drug withdrawal in only 1.3 percent [7, 8]. Pharmacokinetics are characterized by slow subcutaneous absorption (time to peak concentration 33 to 77 hours), limited volume of distribution (approximately 7 liters), low renal clearance (less than 1 percent excreted unchanged in urine), and a long elimination half-life of 60 to 138 hours supporting once-daily dosing [3]. Bioavailability after subcutaneous injection is approximately 57 percent relative to intravenous administration. The compound does not cross the blood-brain barrier [9]. Approximately 17 percent of treated patients develop low-titer, non-neutralizing anti-growth hormone antibodies without apparent impact on efficacy [3]. The compound improves glucose metabolism and insulin sensitivity in acromegaly patients, an advantage over somatostatin analogues that may suppress insulin secretion and worsen glucose homeostasis [10, 11]. This monograph reviews the protein engineering, PEGylation chemistry, and structural pharmacology of pegvisomant; the molecular mechanism of growth hormone receptor antagonism; the comprehensive human pharmacokinetic record; preclinical pharmacology in transgenic and xenograft models; the clinical evidence base across the pivotal registration trial, long-term observational studies, and combination therapy investigations; sourcing and quality verification; reconstitution and handling; stack interactions with somatostatin receptor ligands, dopamine agonists, insulin, and other endocrine agents; the adverse-event and safety signal; and a structured comparative assessment of five alternative acromegaly pharmacotherapies (octreotide, lanreotide, pasireotide, cabergoline, and paltusotine) against pegvisomant on five competency standards (novelty, effect size, promising potential, side-effect profile, and overall validation).

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