Author: kodiac

  • Danuglipron

    Non-peptide small-molecule glucagon-like peptide-1 receptor full agonist

    An orally bioavailable benzimidazole-carboxylic acid developed at Pfizer as the first clinical-stage small-molecule full agonist of the human GLP-1 receptor, distinguished from peptidic GLP-1 receptor agonists by oral bioavailability without absorption enhancers and from other non-peptide candidates by a unique extracellular domain binding mode requiring the primate-specific tryptophan 33 residue.

    Abstract

    Danuglipron (PF-06882961) is an orally bioavailable, non-peptide, small-molecule full agonist of the human glucagon-like peptide-1 receptor (GLP-1R) discovered at Pfizer through a sensitized high-throughput screen of 2.8 million compounds and advanced through Phase 2b clinical development for type 2 diabetes mellitus and obesity before discontinuation in April 2025 following a single case of potential drug-induced liver injury in a dose-optimization study. The compound is a benzimidazole-6-carboxylic acid bearing a piperidine-linked pyridine with a 4-cyano-2-fluorobenzyloxy substituent and an (S)-oxetanylmethyl group (molecular formula C31H30FN5O4; molecular weight 555.61; CAS 2230198-02-2). Danuglipron activates the GLP-1R with nanomolar potency at cAMP accumulation and insulin secretion endpoints in cells expressing human or primate receptor, but is inactive at rodent GLP-1R owing to a species-specific binding pocket that requires tryptophan at position 33 of the receptor extracellular domain (Trp33ECD), a residue that is serine in mouse, rat, and rabbit. A cryogenic electron microscopy structure at 2.5 angstrom resolution (PDB 7S15) revealed that danuglipron binds at the orthosteric peptide-binding site but engages the extracellular domain in a distinct conformation in which the ECD rotates and Trp33 moves approximately 14 angstroms to close the top of the small-molecule binding pocket, a conformational rearrangement not observed with peptide agonists. The compound signals through canonical Gs-coupled cAMP production, beta-arrestin recruitment, and receptor internalization pathways in a manner broadly similar to the endogenous peptide GLP-1(7-36)amide, and is therefore classified as an approximately unbiased full agonist at the receptor level, in contrast to the partial-agonist, Gs-biased profile of the competing small-molecule candidate orforglipron. Pharmacokinetics in humans are characterized by rapid oral absorption with minimal food effect, a terminal elimination half-life of approximately 5 to 6 hours supporting twice-daily dosing for the immediate-release formulation, hepatic clearance predominantly through CYP3A4-mediated oxidative metabolism, hepatic uptake via organic anion-transporting polypeptide transporters OATP1B1, OATP1B3, and OATP2B1, and negligible renal excretion of unchanged drug. In the Phase 1 multiple ascending-dose trial in 98 patients with type 2 diabetes (Saxena et al. 2021, Nature Medicine), danuglipron produced dose-dependent reductions in fasting and postprandial glucose with tolerability limited principally by gastrointestinal adverse events (nausea, vomiting, dyspepsia). In the Phase 2 randomized trial in 411 patients with type 2 diabetes (Saxena et al. 2023, JAMA Network Open), the 120 mg twice-daily dose produced a placebo-adjusted HbA1c reduction of 1.16 percentage points, a fasting plasma glucose reduction of 33.24 mg/dL, and clinically meaningful body weight reduction over 16 weeks. In the Phase 2b obesity trial (Buckeridge et al. 2025, Diabetes, Obesity and Metabolism), placebo-adjusted body weight reductions ranged from 5.0 to 12.9 percent at 26 to 32 weeks, with discontinuation rates exceeding 50 percent across all dose groups principally due to gastrointestinal adverse events. Pfizer discontinued twice-daily danuglipron development in December 2023 due to tolerability concerns and advanced a once-daily modified-release formulation that met pharmacokinetic objectives in dose-optimization studies; however, in April 2025, a single asymptomatic case of potential drug-induced liver injury in a dose-optimization study, combined with a comprehensive portfolio review and regulatory input, led Pfizer to discontinue all danuglipron development. The compound is not approved in any jurisdiction. It is available as a research-grade preparation from multiple chemical suppliers and serves as a critical reference compound for the emerging class of non-peptide oral GLP-1R agonists.

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  • Somatrogon

    Long-acting recombinant human growth hormone receptor agonist (CTP-modified growth hormone fusion protein)

    A long-acting glycoprotein fusion of recombinant human growth hormone with three copies of the C-terminal peptide of human chorionic gonadotropin beta-subunit, engineered by OPKO Health and commercialized by Pfizer as a once-weekly subcutaneous injection for the treatment of pediatric growth hormone deficiency, distinguished from daily somatropin by its prolonged pharmacokinetic profile and from other long-acting growth hormone preparations by its CTP-based half-life extension platform.

    Abstract

    Somatrogon (somatrogon-ghla; CAS 1663481-09-1; approximate molecular weight 40 kDa including glycosylation) is a long-acting recombinant human growth hormone receptor agonist produced in Chinese hamster ovary cells by recombinant DNA technology and approved for the treatment of pediatric growth hormone deficiency as a once-weekly subcutaneous injection. The molecule comprises the complete 191-amino-acid sequence of native human growth hormone with one copy of the 28-amino-acid C-terminal peptide (CTP) from the beta-subunit of human chorionic gonadotropin fused at the N-terminus and two tandem copies of CTP fused at the C-terminus [1, 2]. The CTP cassettes introduce O-linked glycosylation sites that reduce renal clearance, extend the circulating half-life from the 2 to 4 hours of native somatropin to an effective half-life of approximately 28 to 38 hours, and thereby permit once-weekly dosing at 0.66 mg/kg without loss of growth-promoting efficacy relative to daily somatropin [3, 4]. Somatrogon binds the homodimeric growth hormone receptor and activates the JAK2-STAT5b signaling cascade, producing downstream increases in hepatic and peripheral insulin-like growth factor 1 (IGF-1) synthesis, skeletal longitudinal growth, protein anabolism, and modulation of carbohydrate and lipid metabolism identical in pathway to native growth hormone [5, 6]. The pivotal global Phase 3 clinical trial (NCT02968004) randomized 224 treatment-naive prepubertal children with growth hormone deficiency to once-weekly somatrogon (0.66 mg/kg) or once-daily somatropin (Genotropin, 0.24 mg/kg/week) for 12 months and demonstrated non-inferiority of somatrogon on the primary endpoint of annualized height velocity (somatrogon 10.12 cm/year versus somatropin 9.78 cm/year), with height standard deviation score improvements numerically favoring the somatrogon arm [7]. A parallel Phase 3 study in Japanese children confirmed non-inferiority with consistent safety [8]. Long-term extension data through 5 years of treatment demonstrated sustained catch-up growth with a mean height standard deviation score increase from baseline of 1.94 at extension year 4, consistent with durable efficacy [9]. The safety profile is characterized by injection site reactions (pain in 39.4 percent of somatrogon recipients versus 25.2 percent of somatropin recipients), nasopharyngitis, headache, pyrexia, and the pharmacological class effects of growth hormone therapy including transient hyperglycemia, hypothyroidism unmasking, and benign intracranial hypertension [7, 10]. Immunogenicity is notable: 77.1 percent of somatrogon-treated subjects developed anti-drug antibodies during the 12-month pivotal trial versus 15.6 percent of somatropin-treated subjects, but neutralizing antibody activity was not detected, and anti-drug antibodies did not have a clinically significant impact on efficacy or safety through 42 months of observation [7, 11]. Somatrogon received marketing authorization from the European Medicines Agency in January 2022, from Health Canada in December 2021, from the Australian Therapeutic Goods Administration in 2021, and from the United States Food and Drug Administration on June 27, 2023, following an initial complete response letter in January 2022 that required supplementary manufacturing data [12, 13]. The compound is marketed as Ngenla in a prefilled pen presentation requiring no reconstitution. This monograph reviews the molecular design, CTP-based half-life extension technology, growth hormone receptor pharmacology, comprehensive pharmacokinetic characterization, the pediatric clinical evidence base, sourcing and handling considerations, drug interaction profile, adverse event and immunogenicity data, and a structured comparative assessment of five alternative growth hormone preparations against somatrogon 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.

  • 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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    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.

  • SS-20

    Mitochondria-targeted cardiolipin-binding tetrapeptide without intrinsic radical-scavenging activity

    A synthetic Szeto-Schiller tetrapeptide (Phe-D-Arg-Phe-Lys-NH2) that selectively concentrates on the inner mitochondrial membrane through electrostatic and hydrophobic interactions with cardiolipin, restoring electron transport chain coupling efficiency and ATP synthesis under ischemic, oxidative, and age-related stress without direct free-radical scavenging, thereby dissociating mitochondrial protection from antioxidant chemistry and establishing cardiolipin modulation as the operative therapeutic mechanism of the SS peptide class.

    Abstract

    SS-20 (SBT-20; H-Phe-D-Arg-Phe-Lys-NH2; CAS 736992-19-1; molecular weight 595.75; molecular formula C30H45N9O4) is a cell-permeable, mitochondria-targeted synthetic tetrapeptide of the Szeto-Schiller (SS) class, developed at the Department of Pharmacology at Weill Cornell Medical College by Hazel H. Szeto and colleagues as a structural analog of SS-31 (elamipretide) that retains mitochondrial targeting and cardiolipin binding but lacks the 2′,6′-dimethyltyrosine (Dmt) residue responsible for intrinsic reactive oxygen species scavenging in SS-31 [1, 2]. The deliberate substitution of phenylalanine for Dmt at position 1 eliminates the phenolic hydroxyl group that confers direct radical-scavenging capacity, making SS-20 an indispensable mechanistic control compound that has proven essential for establishing that cardiolipin interaction, rather than antioxidant chemistry, is the operative therapeutic mechanism of the SS peptide class [3, 4]. SS-20 carries a net 3+ charge at physiological pH and concentrates approximately 1000-fold on the inner mitochondrial membrane (IMM), where it binds the tetra-acyl dianion cardiolipin through electrostatic interactions between its basic residues (D-Arg, Lys) and the cardiolipin phosphate head groups, with its aromatic phenylalanine residues inserting into the hydrophobic acyl chain region [5, 6]. This binding modulates the interaction between cardiolipin and cytochrome c, promoting the electron carrier function of cytochrome c over its peroxidase activity, thereby improving mitochondrial electron transport chain coupling efficiency, increasing ATP synthesis per unit oxygen consumed, and reducing mitochondrial reactive oxygen species generation as a downstream consequence of improved coupling rather than through direct scavenging [3, 4]. In preclinical models, SS-20 has demonstrated efficacy comparable to SS-31 in protecting against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced dopaminergic neurotoxicity in mice at 4 mg/kg intraperitoneal, with complete preservation of tyrosine hydroxylase-immunoreactive neurons in the substantia nigra pars compacta and 40 percent attenuation of striatal dopamine depletion [7]. In renal ischemia-reperfusion models, pretreatment with SS-20 extended warm ischemia tolerance in rat kidneys from 30 to 45 minutes, preserved cristae architecture on electron microscopy, restored tissue ATP levels, and reduced apoptosis, cytoskeletal breakdown, and interstitial fibrosis [8]. In cardiac ischemia-reperfusion, intravenous SS-20 (SBT-20) at 0.3 and 3.0 mg/kg/hour reduced myocardial infarct size by 20 percent relative to saline control in a rat coronary occlusion model, outperforming the reported 11 percent reduction achieved by elamipretide (MTP-131) in comparable protocols [9]. In pressure-overload heart failure induced by transverse aortic constriction (TAC) in mice, SS-20 produced partial but significant attenuation of cardiac hypertrophy and improvement in fractional shortening, with preferential protection of actin cytoskeletal pathways over mitochondrial and metabolic pathways in global proteomic analysis, a pattern distinct from the broader mitochondrial proteomic protection provided by SS-31 [10]. In chronic renal failure induced by 5/6 nephrectomy in mice, SBT-20 at 5 mg/kg intraperitoneal reduced inflammatory cytokines (interleukin-1-beta, interleukin-6, tumor necrosis factor alpha), normalized NF-kappaB signaling, restored mitochondrial membrane potential, and improved serum creatinine, blood urea nitrogen, and creatinine clearance [11]. The compound has not entered human clinical trials; all pharmacological characterization is preclinical. SS-20 is not approved by any regulatory authority for any indication. It is supplied as a research-grade synthetic peptide by multiple chemical suppliers at greater than 98 percent purity by high-performance liquid chromatography and is used principally as a mechanistic tool to dissect the relative contributions of cardiolipin binding and antioxidant activity within the SS peptide class, and as a candidate therapeutic lead for ischemia-reperfusion injury, neurodegenerative disease, and chronic kidney disease in settings where direct radical scavenging may not be the desired pharmacological intervention.

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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.

  • Memantine

    Plain-language summaryIntrigue 72 / 100

    Memantine, sold as Namenda, is an Alzheimer disease medication that blocks the NMDA glutamate receptor. Unlike most NMDA antagonists it has a brief, low-affinity profile that allows normal learning while preventing the chronic excitotoxicity associated with neurodegeneration. 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.

    Uncompetitive NMDA receptor antagonist with ancillary 5-HT3 antagonist and alpha-7 nicotinic receptor activity

    A 3,5-dimethyladamantane derivative developed by Merz Pharmaceuticals as a moderate-affinity, voltage-dependent, uncompetitive NMDA receptor open-channel blocker approved for moderate-to-severe Alzheimer’s disease, distinguished from high-affinity NMDA antagonists by rapid off-rate kinetics that permit preservation of physiological synaptic transmission while attenuating tonic excitotoxic glutamatergic signaling.

    Abstract

    Memantine (1-amino-3,5-dimethyladamantane; CAS 19982-08-2; molecular formula C12H21N; molecular weight 179.30) is a moderate-affinity, uncompetitive, voltage-dependent, open-channel blocker of the N-methyl-D-aspartate (NMDA) subtype of the ionotropic glutamate receptor, approved in the European Union (2002) and the United States (2003) for the treatment of moderate-to-severe Alzheimer’s disease. The compound is an adamantane derivative structurally related to the antiviral agent amantadine, first synthesized and patented by Eli Lilly and Company in 1968 as a potential antidiabetic agent, subsequently identified as possessing central nervous system activity in the early 1970s by Merz Pharmaceuticals, and characterized as an NMDA receptor channel blocker by Bormann in 1989 [1]. The pharmacological distinction of memantine from high-affinity NMDA channel blockers such as phencyclidine, dizocilpine (MK-801), and ketamine rests on three properties: moderate binding affinity (IC50 approximately 1 micromolar at resting membrane potential), strong voltage dependence that ensures rapid unblocking upon physiological depolarization, and fast open-channel blocking and unblocking kinetics (time constant of unblock approximately 5 seconds) [2, 3]. These kinetic properties allow memantine to attenuate the tonic, pathologically elevated glutamatergic signaling associated with excitotoxic neurodegeneration while preserving the transient, high-amplitude synaptic NMDA receptor activation required for long-term potentiation and normal cognitive function. In addition to the primary NMDA receptor mechanism, memantine acts as a non-competitive antagonist of the serotonin 5-HT3 receptor at concentrations comparable to its NMDA receptor affinity (IC50 approximately 1 to 2 micromolar) [4] and as a non-competitive antagonist of the alpha-7 nicotinic acetylcholine receptor (IC50 approximately 0.34 to 5 micromolar depending on assay conditions) [5]. Weak agonist activity at the sigma-1 receptor (Ki approximately 2.6 micromolar) has been reported but is unlikely to contribute at therapeutic plasma concentrations [6]. Pharmacokinetics in humans are characterized by near-complete oral bioavailability (approximately 100 percent), a long plasma elimination half-life of 60 to 80 hours permitting once- or twice-daily dosing, minimal hepatic cytochrome P450-mediated metabolism, and predominantly renal elimination with approximately 48 percent of the administered dose excreted unchanged in urine through pH-dependent tubular reabsorption and active tubular secretion [7, 8]. The compound is well tolerated at the approved dose of 20 mg per day; the principal adverse events in registration trials were dizziness, headache, confusion, and constipation, occurring at rates comparable to or modestly exceeding placebo [9, 10]. Two pivotal registration trials established efficacy: the Reisberg et al. (2003) study in 252 patients with moderate-to-severe Alzheimer’s disease demonstrated significant benefit over placebo on the Severe Impairment Battery (SIB) and the Clinician’s Interview-Based Impression of Change Plus Caregiver Input (CIBIC-Plus) over 28 weeks [9], and the Tariot et al. (2004) study in 404 patients already receiving stable donepezil demonstrated that the addition of memantine produced significant improvement in cognitive, functional, behavioral, and global measures compared to placebo plus donepezil [10]. Memantine is marketed as Namenda (Forest Laboratories, now Allergan/AbbVie) in the United States, as Axura (Merz) and Ebixa (Lundbeck) in Europe, and under multiple generic names globally. An extended-release formulation (Namenda XR, 28 mg once daily) was approved in 2010, and a fixed-dose combination of memantine extended-release and donepezil (Namzaric, 28 mg/10 mg) was approved in 2014. This monograph reviews the chemistry, synthesis, and structural pharmacology of memantine; the multi-target receptor pharmacology with emphasis on the NMDA receptor mechanism; comprehensive human pharmacokinetics; preclinical neuroprotection and cognition pharmacology; the clinical evidence base across Alzheimer’s disease, vascular dementia, neuropathic pain, and investigational indications; sourcing and quality verification; reconstitution and handling; stack-interaction considerations; adverse events and safety signal; and a comparative assessment of five therapeutic alternatives against memantine on five competency standards.

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  • FGL Peptide

    NCAM-derived FGFR-agonist peptide

    A 15-residue synthetic peptide modeled on the second fibronectin-like domain of neural cell adhesion molecule, an FGFR1 partial agonist with neuroprotective and pro-cognitive activity in rodent models.

    Abstract

    FGL (FG Loop peptide; Glu-Val-Tyr-Val-Val-Ala-Glu-Asn-Gln-Gln-Gly-Lys-Ser-Lys-Ala; sometimes called the FGL peptide or NCAM-derived FGFR agonist; molecular weight approximately 1622 Da) is a synthetic 15-residue peptide modeled on the second fibronectin type III repeat (FnIII) domain of neural cell adhesion molecule (NCAM), specifically the Phe-Gly loop responsible for fibroblast growth factor receptor 1 (FGFR1) interaction. NCAM is a transmembrane glycoprotein expressed at high levels in developing and adult nervous system tissue that mediates cell-cell adhesion through homophilic NCAM-NCAM binding and signals across the membrane through cis-binding to FGFR1. The FGL peptide was designed at the University of Copenhagen by Elisabeth Bock and Vladimir Berezin as a small-molecule mimetic of the NCAM-FGFR interaction, capable of activating FGFR1 signaling without the broad effects of full NCAM ectodomain or full-length FGF ligands. Reported activities include neurite outgrowth promotion in primary cortical and hippocampal neurons, protection against glutamate excitotoxicity, anxiolysis and pro-cognitive effects in rodent fear conditioning and Morris water maze paradigms, and recovery promotion in models of traumatic brain injury and stroke. Routes studied include subcutaneous, intraperitoneal, and intranasal administration. Plasma half-life is short (approximately 30 minutes); the central nervous system exposure after intranasal administration is substantially higher than after parenteral routes, owing to direct olfactory and trigeminal pathway transport. The compound advanced through ENKAM Pharmaceuticals (a University of Copenhagen spin-out) into early clinical development for Alzheimer’s disease and cognitive impairment in the late 2000s; clinical development has not produced a marketed agent. The principal limitation on the strength of the evidence is the dominance of the originating laboratory’s publications and the absence of independent replication of key behavioral findings.

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  • Procaine

    Plain-language summaryIntrigue 42 / 100

    Procaine is the original synthetic local anesthetic, synthesized in 1905 by Alfred Einhorn and marketed by Hoechst as Novocain. It was developed as a non-addictive cocaine substitute and dominated the field from 1905 through the 1950s before lidocaine and the amide class displaced it owing to faster onset, longer duration, and far fewer allergic reactions. The ester-class downside: hydrolysis by plasma cholinesterase produces para-aminobenzoic acid (PABA), the dominant allergen in the class. Plasma half-life of procaine itself is under one minute; clinical infiltration block lasts only 30 to 60 minutes. Modern use is essentially restricted to short-procedure infiltration in patients with documented amide allergy and to a few dental applications. Procaine penicillin (the depot antibiotic formulation) is the oldest application of procaine in pharmaceutical formulation and is the principal reason most clinicians have heard of it. 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.

    Ester local anesthetic (short-acting)

    The original synthetic local anesthetic introduced in 1905 as Novocaine, displaced by amide agents but retaining historical and reference status.

    Abstract

    Procaine (2-(diethylamino)ethyl 4-aminobenzoate; CAS 59-46-1; molecular formula C13H20N2O2; molecular weight 236.31) is the original synthetic local anesthetic, synthesized by Alfred Einhorn at the University of Munich in 1905 and marketed by Hoechst as Novocain. The compound was developed as a cocaine substitute that lacked the abuse liability and addictive potential of the natural alkaloid; the ester linkage between the aromatic ring and the amino alcohol substantially reduces lipophilicity relative to cocaine while preserving sodium channel block. Procaine was the dominant local anesthetic from 1905 through approximately the 1950s, when lidocaine and the amide class displaced it owing to faster onset, longer duration, and substantially lower allergic reaction incidence. The principal limitation of procaine and the ester class is hydrolysis by plasma cholinesterase to para-aminobenzoic acid (PABA), the dominant allergen in the class and a substrate for hapten-mediated immune reactions in sensitized individuals. The plasma half-life is short (less than 1 minute through cholinesterase clearance); duration of clinical infiltration block is 30 to 60 minutes, much shorter than amide agents. Mechanism is voltage-gated sodium channel block with state-dependent kinetics; the lower lipid solubility relative to amide agents corresponds to slower onset and weaker block per milligram. Maximum recommended dose is 7 mg/kg, with adjustment for patients with cholinesterase deficiency (prolonged duration, increased systemic exposure). Modern clinical use is limited to short-procedure infiltration in patients with documented amide allergy and to several dental applications in markets where the ester formulations remain available. Procaine penicillin (combined with penicillin G as a depot) extends antibiotic plasma levels and is the oldest application of procaine in formulation.

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  • Glepaglutide

    Long-acting glucagon-like peptide-2 (GLP-2) receptor agonist peptide analog

    A 39-amino-acid synthetic peptide analog of human glucagon-like peptide-2 engineered by Zealand Pharma with nine amino acid substitutions and a C-terminal hexalysine tail to enable depot formation, extended half-life, and ready-to-use liquid formulation for subcutaneous administration in short bowel syndrome.

    Abstract

    Glepaglutide (ZP1848) is a long-acting, synthetic peptide analog of human glucagon-like peptide-2 (GLP-2) developed by Zealand Pharma A/S (Soeborg, Denmark) for the treatment of short bowel syndrome (SBS) with intestinal failure in patients dependent on parenteral support. The compound comprises 39 amino acids and differs from native human GLP-2(1-33) by the incorporation of nine amino acid substitutions at positions 2, 3, 5, 8, 10, 11, 16, 24, and 28, together with a C-terminal amidated hexalysine tail ([Lys]6-NH2) derived from Zealand Pharma’s proprietary Structure Inducing Probe (SIP) technology. The substitutions confer resistance to dipeptidyl peptidase-4 (DPP-4) degradation, improved physicochemical stability enabling a ready-to-use aqueous liquid formulation, and formation of a subcutaneous depot from which the parent compound and its active C-terminally truncated metabolites (M1, 35 amino acids; M2, 34 amino acids) are slowly released into systemic circulation. The resulting effective half-life of approximately 50 to 124 hours in humans permits twice-weekly or once-weekly subcutaneous dosing, a substantial advance over the daily injection requirement of teduglutide (Gattex), the first-in-class approved GLP-2 analog. Glepaglutide binds and activates the GLP-2 receptor (GLP-2R), a class B G-protein-coupled receptor expressed on intestinal subepithelial myofibroblasts, enteroendocrine cells, and enteric neurons. Receptor activation triggers downstream release of intestinal growth mediators including insulin-like growth factor-1 (IGF-1), epidermal growth factor (EGF), and keratinocyte growth factor, resulting in crypt cell proliferation, villus elongation, inhibition of enterocyte apoptosis, enhanced intestinal barrier function, increased mesenteric blood flow, and suppression of gastric acid hypersecretion and accelerated gastrointestinal motility. The net physiological effect is increased intestinal absorptive capacity for fluid, electrolytes, and macronutrients in patients with anatomically shortened bowel. Clinical development has progressed through Phase 1 healthy volunteer pharmacokinetic studies, a Phase 2 randomized crossover trial in 18 SBS patients published in The Lancet Gastroenterology and Hepatology (Naimi et al., 2019) demonstrating dose-dependent improvements in intestinal wet weight absorption and plasma citrulline, and the pivotal Phase 3 EASE-SBS 1 trial (NCT03690206), a multinational, double-blind, placebo-controlled study in 106 patients that met its primary endpoint of significant reduction in weekly parenteral support volume at 24 weeks (mean change minus 5.13 versus minus 2.85 liters per week for glepaglutide twice weekly versus placebo; P equals 0.0039). The compound received orphan drug designation from both the United States Food and Drug Administration and the European Medicines Agency. Zealand Pharma submitted a New Drug Application to the FDA in late 2023; in December 2024, the FDA issued a Complete Response Letter citing insufficient evidence to confirm efficacy and safety at the proposed marketed dose and recommending an additional confirmatory trial. A Marketing Authorization Application was submitted to the European Medicines Agency in June 2025, and Zealand Pharma plans an additional Phase 3 trial to support regulatory resubmission in the United States. The safety profile is consistent with the known GLP-2 class effects. The most frequent adverse events in clinical trials are injection site reactions, stoma complications (primarily swelling or enlargement of the stoma nipple), gastrointestinal events (nausea, vomiting, abdominal pain), peripheral edema, fatigue, and headache. Anti-drug antibodies develop in a proportion of treated patients with a trend toward higher injection site reaction incidence in antibody-positive individuals, though no firm causal relationship has been established. The compound does not require reconstitution and is administered as a fixed-dose, ready-to-use subcutaneous injection via autoinjector, representing a practical advantage over lyophilized GLP-2 analogs requiring daily preparation. This monograph documents the chemistry, design rationale, and synthesis of glepaglutide; the GLP-2 receptor pharmacology and downstream intestinotrophic signaling; the comprehensive human pharmacokinetic profile including depot formation and metabolite characterization; the preclinical pharmacology in intestinal growth and inflammatory bowel disease models; the clinical evidence base from Phase 1 through Phase 3; sourcing and quality verification; reconstitution and handling; stack interaction considerations; adverse events and safety signals; and a comparative assessment of five GLP-2 receptor agonist candidates (teduglutide, apraglutide, dapiglutide, elsiglutide, and native GLP-2) against glepaglutide on five competency standards.

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  • Tabimorelin

    Orally active peptidomimetic growth hormone secretagogue and ghrelin receptor (GHSR1a) agonist

    A modified polypeptide derived from ipamorelin at Novo Nordisk, representing the first orally bioavailable peptidomimetic ghrelin receptor agonist advanced to Phase 2 clinical evaluation for adult growth hormone deficiency, distinguished by mechanism-based CYP3A4 inhibition and GH-axis tachyphylaxis that limited its clinical development.

    Abstract

    Tabimorelin (NN703; CAS 193079-69-5; molecular formula C32H40N4O3; molecular weight 528.70) is a potent, orally active agonist of the growth hormone secretagogue receptor type 1a (GHSR1a, the ghrelin receptor), developed by Novo Nordisk as a non-injectable alternative to recombinant growth hormone therapy in adult growth hormone deficiency. The compound was derived from the selective pentapeptide growth hormone secretagogue ipamorelin (NNC 26-0161) through systematic backbone reduction and pharmacophore optimization conducted principally by Ankersen, Hansen, and colleagues in the late 1990s, yielding a tripeptide-like structure with oral bioavailability of approximately 30 percent in dogs and a plasma half-life of approximately 4.1 hours in the same species [1]. Tabimorelin binds the GHSR1a receptor and activates the Gq/11-coupled phospholipase C signaling cascade, producing calcium mobilization from intracellular stores, membrane depolarization, and pulsatile growth hormone release from anterior pituitary somatotroph cells. In single-dose Phase 1 studies in healthy male volunteers at doses of 0.05 to 12 mg/kg, the compound produced dose-dependent increases in growth hormone area under the curve and peak concentration, with significant elevations in GH AUC at 3.0 mg/kg (P = 0.027), 6.0 mg/kg (P = 0.0023), and 12 mg/kg (P < 0.0001), together with significant increases in insulin-like growth factor 1 (IGF-1) at the two highest dose levels [2]. In a 7-day repeated-dose Phase 1 study at four dose levels (1.71, 3.0, 4.5, and 6.86 mg/kg once daily), GH release remained significantly elevated above placebo on both days 1 and 7, but an overall significant decrease in GH release from day 1 to day 7 (P < 0.001) demonstrated tachyphylaxis at the somatotroph axis level [3]. IGF-1 and IGF binding protein 3 (IGFBP-3) increased at all dose levels, with significantly greater IGF-1 elevation at the three highest doses. The compound produced transient increases in prolactin and adrenocorticotropic hormone (ACTH) on day 1 that resolved by day 7, with no significant cortisol elevation on either assessment day [3]. The pivotal Phase 2 study enrolled 97 adults with confirmed growth hormone deficiency in a multicentre, randomized, double-blind, placebo-controlled design; only 9 of 83 NN703-treated patients (11 percent) achieved a serum peak GH concentration of 5 micrograms per liter or greater, and 1-week treatment did not significantly increase IGF-1, although IGFBP-3 was modestly elevated [4]. The limited clinical response was attributed to the severity of hypothalamic-pituitary axis disruption in the GH-deficient population, which depends on residual somatotroph capacity for a secretagogue mechanism to function. A separate clinical pharmacology investigation established that tabimorelin is a mechanism-based (irreversible) inhibitor of cytochrome P450 3A4, increasing midazolam AUC by 64 percent after a single dose and by 93 percent after 7 days of dosing, with persistent 45 percent elevation even after a 7-day washout [5]. This CYP3A4 liability, combined with the modest clinical efficacy in the target population and the GH tachyphylaxis on repeated dosing, led Novo Nordisk to discontinue clinical development. Tabimorelin remains a research-grade compound of interest for fundamental GHSR1a pharmacology, for structure-activity investigation within the peptidomimetic ghrelin agonist class, and as a comparator in the broader landscape of growth hormone secretagogues that includes ibutamoren (MK-0677), anamorelin, macimorelin, and capromorelin. The compound is not approved by any regulatory authority for human therapeutic use. It is supplied as a research-grade preparation by multiple chemical suppliers; investigators should obtain analytical confirmation of identity and purity on every lot.

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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.

  • Vilon

    Synthetic immunomodulatory dipeptide bioregulator of thymic origin with epigenetic chromatin-remodeling activity

    A synthetic dipeptide (L-Lys-L-Glu) derived from structural analysis of the thymic polypeptide complex Thymalin, developed at the Saint Petersburg Institute of Bioregulation and Gerontology as the smallest bioactive peptide bioregulator with immunomodulatory, geroprotective, and epigenetic chromatin-reactivation activity in aging immune cells.

    Abstract

    Vilon (L-lysyl-L-glutamic acid; KE dipeptide; CAS 45234-02-4; molecular formula C11H21N3O5; molecular weight 275.30 g/mol) is a synthetic dipeptide bioregulator developed by Vladimir Khavinson and colleagues at the Saint Petersburg Institute of Bioregulation and Gerontology as the minimal pharmacophore unit of the thymic polypeptide extract Thymalin. The compound represents the shortest bioactive peptide characterized in the Khavinson bioregulatory peptide class, consisting of a single lysine residue bonded to a single glutamic acid residue in the alpha-peptide linkage. Despite its minimal chain length, Vilon has demonstrated reproducible immunomodulatory, anti-tumor, geroprotective, and epigenetic activity across more than two decades of experimental investigation conducted primarily in Russian academic institutions and published in the Bulletin of Experimental Biology and Medicine, Biogerontology, Advances in Gerontology, and the International Journal of Molecular Sciences. The principal molecular mechanism, characterized by Lezhava, Khavinson, and Jokhadze in a series of cytogenetic studies from 2003 to 2023, is sequence-specific binding to the tetranucleotide motif TCGA in gene promoter regions, producing deheterochromatinization (decondensation of constitutive and facultative heterochromatin) in aging lymphocytes and thymocytes, with consequent reactivation of ribosomal genes and release of age-repressed transcriptional programs [1, 2, 3]. The immunomodulatory activity, characterized in thymic cell cultures and in the THP-1 monocyte/macrophage cell line, includes upregulation of CD4 and CD5 T-lymphocyte differentiation markers, enhancement of nucleolar organizer region associated protein expression, stimulation of interleukin-2 gene expression in blood lymphocytes, and suppression of lipopolysaccharide-induced tumor necrosis factor alpha and interleukin-6 release from terminally differentiated macrophages [4, 5, 6]. The geroprotective profile, established in female CBA mice receiving subcutaneous Vilon from 6 months of age through the lifespan, includes increased mean lifespan by approximately 24 percent, increased physical activity and endurance, decreased body temperature, and reduced incidence of spontaneous neoplasms including lung adenomas and lymphomas [7, 8]. Antitumor activity was independently confirmed in a chemically induced rat urinary bladder carcinogenesis model, where Vilon reduced tumor incidence from 75.5 percent to 56 percent and inhibited preneoplastic changes in the urothelial mucosa [9]. Clinical application in the Russian Federation, where Vilon has been used in investigational and observational settings for postoperative immune reconstitution, chronic infection management, geriatric immune support, and adjunctive diabetes mellitus management, has produced reports of insulin dose reduction (mean 9 units) in 150 patients with type 1 diabetes and favorable tolerability with no consistent adverse events across multiple cohort studies [10, 11, 12]. Pharmacokinetic data from intestinal tract and liver homogenate studies demonstrate that the KE dipeptide resists hydrolysis in small intestinal preparations and is only marginally degraded in large intestinal and hepatic preparations, supporting oral and parenteral bioavailability [13]. The compound is not approved by the United States Food and Drug Administration or by the European Medicines Agency. It is not registered as a pharmaceutical product outside the Russian Federation. Research-grade Vilon is supplied by multiple peptide synthesis vendors at greater than 98 percent purity by high-performance liquid chromatography. This monograph reviews the chemistry, synthesis, and structural characterization of Vilon; the epigenetic and immunomodulatory mechanisms in molecular detail; the pharmacokinetic data; the preclinical geroprotective and antitumor evidence; the clinical observational evidence; sourcing, reconstitution, and stack-interaction considerations; the adverse-event profile; and a comparative assessment of five thymic and immunomodulatory peptide bioregulators (Thymogen, Thymalin, Thymosin alpha-1, Thymulin, Epithalon) against Vilon 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.