Tag: MONOGRAPH

  • Turinabol

    4-chloro-substituted 17alpha-alkylated anabolic-androgenic steroid derived from metandienone with dissociated anabolic-to-androgenic activity ratio

    A 4-chloro-1,2-dehydro-17alpha-methyltestosterone developed at Jenapharm as a clinical anabolic agent for muscle wasting and bone density disorders, distinguished from its parent compound metandienone by the 4-chloro substitution that eliminates aromatase substrate activity and confers a markedly dissociated anabolic-to-androgenic ratio.

    Abstract

    Chlorodehydromethyltestosterone (CDMT), marketed as Oral Turinabol, is a synthetic anabolic-androgenic steroid (AAS) first synthesized by chemist Albert Stachowiak at Jenapharm in the German Democratic Republic and patented in 1961. The compound is the 4-chloro-substituted derivative of metandienone (Dianabol), combining structural elements of clostebol (4-chlorotestosterone) and metandienone (1,2-dehydro-17alpha-methyltestosterone). The 4-chloro substitution at the A-ring prevents aromatization to estrogenic metabolites, while the 1,2-dehydro modification and the 17alpha-methyl group confer oral bioavailability and a dissociated anabolic-to-androgenic ratio of approximately 54:6 relative to methyltestosterone. Introduced for clinical use in 1965 for the treatment of muscle wasting disorders, osteoporosis, and recovery from debilitating illness, CDMT was prescribed at therapeutic doses of 5 to 10 mg per day in adults and 1 to 2.5 mg per day in women and children [1, 2].

    The compound occupies a singular position in pharmacological and sporting history as the principal agent of State Plan Topic 14.25 (Staatsplanthema 14.25), the systematic doping program administered by the German Democratic Republic’s Sports Medical Service from 1974 through 1989, under which approximately ten thousand athletes received CDMT, frequently without informed consent and often described to recipients as vitamins [3, 4]. The program produced a generation of international athletic dominance and a subsequent generation of adverse health consequences in exposed athletes, including hepatotoxicity, endocrine disruption, virilization in female athletes, and cardiovascular morbidity. Production was discontinued by Jenapharm in 1994, and the compound holds no current marketing authorization in any jurisdiction.

    Pharmacokinetically, CDMT is characterized by complete oral absorption, hepatic first-pass metabolism through multiple cytochrome P450 pathways (principally CYP3A4 for 6beta-hydroxylation and mitochondrial CYP11A1, CYP11B1, and CYP11B2 for 11beta-hydroxylation and additional oxidative transformations), and a plasma elimination half-life of approximately 16 hours [5, 6, 7]. The compound produces extensive phase I and phase II metabolites, with approximately 50 urinary metabolites identified. Of particular significance to anti-doping science, the long-term metabolite 4-chloro-18-nor-17beta-hydroxymethyl,17alpha-methyl-5beta-androst-13-en-3alpha-ol, identified by Schanzer and colleagues and subsequently confirmed in controlled human administration studies, extends the urinary detection window to 40 to 50 days after a single dose and potentially longer with chronic administration, enabling retrospective detection of CDMT use in athletes [8, 9, 10].

    The pharmacology of CDMT is that of a moderate-affinity androgen receptor agonist with strong dissociation between anabolic (nitrogen-retentive, myotrophic) and androgenic (virilizing, sebotropic) activities. The compound does not undergo 5alpha-reduction to more potent androgens, does not serve as an aromatase substrate, and binds sex hormone-binding globulin (SHBG) with sufficient affinity to displace endogenous androgens and elevate free testosterone fractions in the presence of concurrent testosterone [11]. The principal adverse effects are dose-dependent hepatotoxicity (consistent with the 17alpha-alkylated steroid class), suppression of the hypothalamic-pituitary-gonadal axis with reduction of luteinizing hormone, follicle-stimulating hormone, and endogenous testosterone production, unfavorable alterations in serum lipid profiles (suppression of high-density lipoprotein cholesterol and elevation of low-density lipoprotein cholesterol), and, in female subjects, irreversible virilization at supratherapeutic doses [12, 13]. This monograph reviews the chemistry, synthesis, and structural pharmacology of CDMT; the receptor-level mechanism of action; the comprehensive metabolic and pharmacokinetic profile including anti-doping detection science; the preclinical pharmacology; the limited clinical evidence base; sourcing and quality considerations; reconstitution and handling; stack interactions; adverse events and safety signals; and a structured comparative assessment of five alternative oral anabolic-androgenic steroids against CDMT 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.

  • Dianabol

    Synthetic 17-alpha-alkylated anabolic-androgenic steroid; testosterone derivative with C1-C2 dehydrogenation

    A 17-alpha-methylated, delta-1-dehydrogenated testosterone derivative developed at CIBA as an orally bioavailable anabolic agent, historically prescribed for catabolic wasting, osteoporosis, and nitrogen-balance restoration, and now principally encountered as a controlled substance of research interest in androgen receptor pharmacology, steroid metabolism, and anabolic-androgenic steroid toxicology.

    Abstract

    Metandienone (International Nonproprietary Name), known commercially as Dianabol and chemically as 17-alpha-methyl-delta-1-testosterone, is a synthetic anabolic-androgenic steroid (AAS) of the androstane class first synthesized at CIBA Pharmaceuticals in Switzerland in the mid-1950s and introduced to the United States prescription market in 1958. The compound is a structural modification of testosterone bearing two critical alterations: a methyl group at the C17-alpha position that confers oral bioavailability by resisting hepatic first-pass metabolism, and a delta-1 (C1-C2) double bond that modifies the anabolic-to-androgenic activity ratio relative to the parent hormone. Metandienone binds the androgen receptor (AR) in skeletal muscle, prostate, and other androgen-responsive tissues, initiating genomic signaling cascades that increase protein synthesis, nitrogen retention, and glycogenolysis. The compound undergoes aromatization by the CYP19A1 (aromatase) enzyme to 17-alpha-methylestradiol, producing dose-dependent estrogenic effects including fluid retention and gynecomastia. Hepatic metabolism proceeds principally through CYP3A4-catalyzed 6-beta-hydroxylation, with additional pathways including 5-beta-reduction, 3-alpha and 3-beta oxidation, and 17-epimerization; the 17-alpha-alkylation that confers oral bioavailability simultaneously produces the hepatotoxicity characteristic of this structural class.

    The compound was originally developed and marketed for the treatment of catabolic states, post-surgical recovery, osteoporosis, and hypogonadism. Clinical trials conducted in the late 1950s and 1960s demonstrated significant positive nitrogen balance at oral doses of 5 to 10 mg per day, with measurable increases in lean body mass and appetite stimulation. However, escalating recognition of the hepatotoxic, cardiovascular, endocrine-suppressive, and estrogenic adverse-effect profile led to progressive restriction of approved indications, and the United States Food and Drug Administration withdrew approval in 1983. The compound is currently classified as a Schedule III controlled substance in the United States under the Controlled Substances Act and is prohibited by the World Anti-Doping Agency. It is not approved for any medical indication in any major regulatory jurisdiction.

    Despite the absence of current clinical approval, metandienone remains a compound of substantial research interest. Its well-characterized androgen receptor pharmacology, its defined hepatotoxic mechanism as a model 17-alpha-alkylated steroid, its known metabolic pathways and urinary metabolite profile (exploited extensively in anti-doping analytical chemistry), and its historical clinical dataset in nitrogen-balance and muscle-wasting research provide a comprehensive pharmacological record. Preclinical studies in rat models have demonstrated that metandienone stimulates levator ani muscle hypertrophy through androgen receptor activation, suppresses the hypothalamic-pituitary-testicular axis, and modulates myostatin signaling pathways. This monograph reviews the chemistry, synthesis, and stereochemistry of metandienone; the androgen receptor pharmacology and mechanism of action; the comprehensive pharmacokinetic record including hepatic metabolism and urinary metabolite detection; the historical clinical evidence base; sourcing and quality verification considerations for research-grade material; reconstitution and handling; stack-interaction considerations; the adverse-event and safety signal across hepatic, cardiovascular, endocrine, and estrogenic domains; and a comparative assessment of five alternative anabolic-androgenic steroids (testosterone, oxandrolone, oxymetholone, stanozolol, nandrolone decanoate) against metandienone on five competency standards (oral bioavailability, anabolic efficacy, hepatotoxicity profile, estrogenic burden, and overall risk-benefit in research contexts).

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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.

  • GB-115

    Retrodipeptide cholecystokinin-1 (CCK-1) receptor antagonist with anxiolytic, anti-inflammatory, analgesic, and immunomodulatory activity

    A synthetic retrodipeptide analogue of cholecystokinin tetrapeptide (CCK-4) designed at the Zakusov Research Institute of Pharmacology, distinguished by selective central CCK-1 receptor antagonism, non-benzodiazepine anxiolytic activity, and a favorable safety profile confirmed through Phase 3 clinical evaluation under the trade name Ranquilon.

    Abstract

    GB-115 (N-(6-phenylhexanoyl)-glycyl-L-tryptophan amide; CAS 678996-63-9) is a synthetic retrodipeptide analogue of the endogenous anxiogenic tetrapeptide cholecystokinin-4 (CCK-4, Trp-Met-Asp-Phe-NH2), designed and synthesized at the V.V. Zakusov Research Institute of Pharmacology (Russian Academy of Medical Sciences) using the topochemical Shemyakin-Ovchinnikov-Ivanov principle for rational peptide drug design. The compound functions as a selective antagonist of the central cholecystokinin type 1 (CCK-1) receptor, producing anxiolytic activity in rodent and primate behavioral models at doses of 0.05 to 0.2 mg/kg without the sedation, tolerance, dependence, or cognitive impairment associated with benzodiazepine anxiolytics. The biologically active conformation of GB-115 has been identified by nuclear Overhauser effect NMR spectroscopy as a type II beta-turn, with the native spatial distance between the phenyl and indolyl hydrophobic pharmacophores critical for receptor interaction. Structure-activity relationship studies demonstrated that L-tryptophan-containing derivatives produce anxiolytic effects, while D-tryptophan-containing enantiomers produce anxiogenic effects mirroring CCK-4 itself, confirming the stereospecificity of the CCK-1 receptor interaction.

    Preclinical pharmacology extends beyond anxiolysis. GB-115 potentiates morphine-induced analgesia through supraspinal opioidergic mechanisms and produces independent antinociceptive activity in chemical and thermal pain models with a significant non-opioid component. Anti-inflammatory effects have been demonstrated in concanavalin A-induced and carrageenan-induced inflammation models and in experimental autoimmune encephalomyelitis in C57Bl/6 mice, where intraperitoneal administration at 1 mg/kg significantly alleviated pathological symptoms, promoted thymus weight recovery, and reduced perivascular edema and neutrophil infiltration of brain tissue. Immunomodulatory activity includes stimulation of phagocytic activity of peritoneal macrophages and humoral immune response in intact mice and immunocorrecting effects in animals with secondary immunodeficiency. The compound reverses antinociceptive tolerance to morphine on sub-chronic co-administration, a property consistent with its CCK-1 receptor antagonist mechanism given the established role of cholecystokinin in opioid tolerance.

    Pharmacokinetics are characterized by rapid oral absorption, low absolute bioavailability (approximately 4.65 percent in animal models), and a short elimination half-life of approximately 1.0 hour in humans. The amide bond confers greater peptidase resistance than native peptide bonds, extending plasma detection time relative to unmodified dipeptides. Acute toxicity is very low, with an oral LD50 exceeding 6000 mg/kg in rodents, providing a therapeutic index of approximately 30,000 to 60,000 relative to the effective anxiolytic dose range.

    Clinical evaluation has progressed through Phase 2 and Phase 3 trials. An open-label pilot study in 25 patients with generalized anxiety disorder demonstrated significant reduction in Hamilton Anxiety Rating Scale (HAM-A) total scores from a median of 22 at baseline to 5 at day 21 on 6 mg daily oral dosing (p < 0.001), with concurrent improvement in cognitive processing speed, attention, and reaction time, and no stimulation-related adverse events. A Phase 3 double-blind, randomized, placebo-controlled, multicenter trial (NCT05586789) in 220 patients with anxiety associated with neurasthenia and adjustment disorders confirmed superiority of Ranquilon 6 mg daily over placebo in reducing anxiety, with all recorded adverse events classified as mild and no serious adverse events or treatment discontinuations. A Phase 4 open-label comparative trial (NCT06843044) against fabomotizole (Afobazole) 30 mg daily is currently recruiting. This monograph reviews the chemistry, design rationale, and stereochemistry of GB-115; the CCK-1 receptor antagonist mechanism and downstream pharmacology; the preclinical evidence across anxiolytic, analgesic, anti-inflammatory, and immunomodulatory applications; the clinical evidence base including Phase 2 and Phase 3 data; pharmacokinetics across species; sourcing and quality verification; reconstitution and handling; stack interactions; adverse events and safety; and a comparative assessment of five anxiolytic or CCK-modulating alternatives against GB-115 on five competency standards.

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  • ISRIB

    Small-molecule eIF2B activator and integrated stress response inhibitor

    A symmetrical bis-glycolamide that stabilizes the decameric eIF2B holoenzyme, counteracting phospho-eIF2alpha-mediated translational repression and reversing age-related, traumatic, and neurodegenerative cognitive deficits in preclinical models without the pancreatic toxicity of upstream PERK kinase inhibitors.

    Abstract

    ISRIB (integrated stress response inhibitor) is a cell-permeable, brain-penetrant small molecule identified by Sidrauski et al. (2013) at the University of California, San Francisco, through a phenotypic screen for compounds that render cells resistant to the translational consequences of eukaryotic initiation factor 2 alpha (eIF2alpha) phosphorylation [1]. The compound blocks the integrated stress response (ISR) with an IC50 of approximately 5 nM in ATF4 reporter assays, operating downstream of all four eIF2alpha kinases (PERK, GCN2, HRI, PKR) at the level of the guanine nucleotide exchange factor eIF2B [2]. Cryo-electron microscopy studies (Tsai et al. 2018; Zyryanova et al. 2021) demonstrated that ISRIB binds at the symmetry interface of two eIF2B betagammadeltaepsilon tetrameric subcomplexes, acting as a molecular staple that promotes assembly of the catalytically active decameric holoenzyme and allosterically antagonizes the inhibitory effect of phosphorylated eIF2alpha on the nucleotide exchange reaction [3, 4]. The resulting restoration of ternary complex formation and global protein synthesis rates is partial rather than complete, reaching approximately 50 to 70 percent of unstressed control levels even at saturating compound concentrations, a feature that accounts for the favorable safety profile relative to direct PERK kinase inhibitors such as GSK2606414 that produce pancreatic exocrine destruction [5].

    Preclinical pharmacology spans multiple disease-relevant models. In cognition, ISRIB enhances spatial and fear-associated learning in wild-type mice (Sidrauski et al. 2013) [1], reverses cognitive deficits weeks after traumatic brain injury (Chou et al. 2017) [6], restores age-related memory decline and hippocampal neuronal function within days of treatment in aged mice (Krukowski et al. 2020) [7], and rescues synaptic plasticity in a mouse model of Down syndrome [8]. In neurodegeneration, ISRIB prevents neuronal loss in prion-diseased mice without pancreatic toxicity (Halliday et al. 2015) [5] and stabilizes vanishing white matter disease eIF2B mutant complexes to wild-type catalytic activity (Wong et al. 2018) [9]. Additional preclinical activity has been reported in prostate cancer [10], noise-induced cochlear synaptopathy [11], postinfarct atrial fibrillation [12], and amyotrophic lateral sclerosis models [13]. Pharmacokinetically, ISRIB exhibits good blood-brain barrier penetration and achieves brain concentrations exceeding its IC50 at intraperitoneal doses of 0.25 to 2.5 mg/kg in mice, but is limited by poor aqueous solubility requiring vehicle formulations with dimethyl sulfoxide and polyethylene glycol 400 [5, 6].

    No human clinical trials of ISRIB itself have been conducted. However, the compound served as the pharmacological prototype for two clinical-stage eIF2B activators: DNL343 (Denali Therapeutics), which completed a Phase 2/3 trial in amyotrophic lateral sclerosis (HEALEY platform trial) without meeting primary endpoints [14], and fosigotifator (Calico/AbbVie), which also failed to demonstrate significant slowing of disease progression in the same platform trial, although an exploratory high-dose arm showed signals on muscle strength preservation [15]. This monograph reviews the chemistry, stereochemistry, and synthesis of ISRIB; the molecular pharmacology of eIF2B activation and ISR inhibition; pharmacokinetic properties and formulation challenges; the preclinical evidence base across cognitive, neurodegenerative, oncologic, and inflammatory models; the clinical-translational status through derivative compounds; sourcing and quality verification for research use; reconstitution and handling; stack interactions; adverse events and safety signals; and a comparative assessment of five ISR-modulating alternatives against ISRIB 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.

  • Cortexin

    Plain-language summaryIntrigue 52 / 100

    Cortexin is a Russian-developed bovine cortex peptide hydrolysate, similar in concept to cerebrolysin but from cerebral cortex tissue rather than whole brain. Used in Russia for stroke and cognitive impairment. 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.

    Polypeptide bioregulator complex derived from cerebral cortex with neurotrophic, neuroprotective, and nootropic activity

    A heterogeneous low-molecular-weight neuropeptide preparation extracted from the cerebral cortex of young cattle and pigs, registered in the Russian Federation as a neuroprotective agent for cerebrovascular disorders, traumatic brain injury, cognitive impairment, and perinatal central nervous system lesions, distinguished from Cerebrolysin by cortex-specific sourcing and intramuscular administration.

    Abstract

    Cortexin is a lyophilized complex of water-soluble polypeptide fractions with molecular weights ranging from 1,000 to 10,000 Daltons, obtained by acetic acid extraction from the cerebral cortex of cattle and pigs younger than 12 months of age. The preparation contains predominantly acidic and neutral polypeptides (70 to 95 percent of total mass), free amino acids (including glutamic acid, aspartic acid, glycine, serine, lysine, and alanine as quantitatively predominant species), and trace quantities of vitamins, minerals, and fatty acids. Unlike single-sequence peptide therapeutics, Cortexin is a heterogeneous mixture without a defined primary structure, and its pharmacological activity is attributed to the collective action of multiple bioactive peptide fractions rather than to any single molecular entity.

    The compound was developed within the Soviet and subsequently Russian bioregulator research program led by Vladimir Khavinson at the Saint Petersburg Institute of Bioregulation and Gerontology beginning in the 1980s, with the first clinical applications in military and aerospace medicine. Cortexin received pharmaceutical registration in the Russian Federation in 1999 and is manufactured by GEROPHARM LLC (Saint Petersburg) as a lyophilisate for intramuscular injection at 5 mg and 10 mg strengths, with glycine (12 mg) as the stabilizing excipient. The compound is registered in Russia, Ukraine, Kazakhstan, Belarus, Uzbekistan, and several other Commonwealth of Independent States jurisdictions for the treatment of acute and chronic cerebrovascular disorders, traumatic brain injury, cognitive impairment, encephalopathy of various origins, epilepsy as adjunctive therapy, and perinatal central nervous system lesions in children. It is not registered or approved in the European Union, the United States, Japan, or any jurisdiction with International Council for Harmonisation regulatory standards.

    The molecular mechanisms of Cortexin are pleiotropic and incompletely characterized at the individual peptide level. Demonstrated activities include modulation of glutamatergic transmission through interaction with AMPA receptors, kainate receptors, and metabotropic glutamate receptors (mGluR1 and mGluR5); GABAergic modulation through GABA-A receptor binding; activation of neurotrophic signaling cascades including brain-derived neurotrophic factor and nerve growth factor pathways; antioxidant activity through restoration of pro-oxidant and antioxidant system balance; anti-inflammatory action at both cerebral and systemic levels; and anti-apoptotic effects on neurons under ischemic and excitotoxic stress. Radioactively labeled Cortexin peptides have been demonstrated to cross the blood-brain barrier in mice, supporting direct central nervous system activity. Neuron-specific proteins including beta-5-tubulin, creatine kinase B, and protein 14-3-3 alpha/beta have been identified as molecular partners of Cortexin peptides in brain tissue.

    The clinical evidence base for Cortexin is substantial within the Russian-language medical literature but limited in the international peer-reviewed literature. The largest body of evidence supports efficacy in acute ischemic stroke, where Cortexin at 10 mg twice daily intramuscularly for 10 days is included in Russian national clinical practice guidelines. A multicenter randomized controlled study (Fedin et al. 2018) demonstrated dose-dependent effects of Cortexin (10 mg versus 20 mg versus standard care alone) on neurological deficit severity, asthenia, and sleep disturbance in patients with chronic cerebral ischemia, with antioxidant effects confirmed by laboratory markers regardless of dose. A multicenter study of cognitive dysfunction in children demonstrated improvement in attention, visual memory, and thinking in pediatric patients with consequences of perinatal central nervous system lesions. In cerebral palsy with comorbid epilepsy, Cortexin as adjunctive therapy reduced seizure frequency by more than two-fold in 36.9 percent of patients while improving motor function. Comparative preclinical studies have demonstrated neuroprotective efficacy comparable to Cerebrolysin and superior to Actovegin in rat models of acute and chronic brain ischemia. A systematic review of animal-derived nootropics noted that the limited number of eligible Cortexin studies precluded meta-analysis, though available data suggested potential efficacy with no safety concerns. The compound is generally well tolerated; the principal adverse events are injection site reactions (8 to 15 percent), headache (5 to 12 percent), dizziness (3 to 8 percent), and rare hypersensitivity reactions including anaphylaxis. This monograph reviews the composition, extraction methodology, and physicochemical properties of Cortexin; the pleiotropic molecular pharmacology; the pharmacokinetic limitations inherent to a heterogeneous peptide preparation; the clinical evidence base across cerebrovascular, traumatic, cognitive, and pediatric indications; sourcing and quality verification considerations; reconstitution and handling protocols; stack-interaction implications; adverse-event signal; and a structured comparative assessment of five neuroprotective alternatives against Cortexin on five competency standards.

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  • BPAP

    Tryptamine-derived synthetic monoaminergic activity enhancer (MAE) with catecholaminergic and serotonergic impulse-propagation-mediated release enhancement and TAAR1 agonism

    A benzofuran-containing synthetic enhancer substance developed by Knoll and colleagues as the most potent known monoaminergic activity enhancer, selectively amplifying impulse-dependent release of dopamine, norepinephrine, and serotonin in the brain without monoamine oxidase inhibition or amphetamine-like releasing activity.

    Abstract

    (-)1-(Benzofuran-2-yl)-2-propylaminopentane, designated (-)BPAP and also known by the developmental code FPFS-1169, is a synthetic monoaminergic activity enhancer (MAE) structurally derived from phenylpropylaminopentane (PPAP) through replacement of the phenyl ring with a benzofuran heterocycle. First described by Jozsef Knoll and colleagues in 1999, BPAP represents the most potent synthetic enhancer substance characterized to date, approximately 130-fold more potent than selegiline ((-)-deprenyl) in antagonizing tetrabenazine-induced performance inhibition in the rat shuttle box paradigm, and is the first enhancer substance to augment serotonergic neurotransmission in addition to the catecholaminergic enhancement shared with selegiline and PPAP. The compound selectively amplifies the quantity of dopamine, norepinephrine, and serotonin released per nerve impulse from monoaminergic neurons without inducing spontaneous (impulse-independent) neurotransmitter release, a pharmacological property that distinguishes it fundamentally from amphetamine-type releasing agents and from monoamine oxidase inhibitors. The mechanism of the enhancer effect has been attributed, on the basis of pharmacological antagonism studies using the selective antagonist EPPTB, to agonism at trace amine-associated receptor 1 (TAAR1), which triggers PKC-dependent phosphorylation of SNARE complex proteins and vesicular monoamine transporter 2 (VMAT2), thereby increasing vesicular monoamine accumulation and exocytotic release. At substantially higher concentrations, BPAP also inhibits monoamine reuptake (predominantly dopamine and norepinephrine), though this activity is not considered pharmacologically relevant at the low nanogram-per-milliliter concentrations that produce the enhancer effect. In preclinical pharmacology, BPAP has demonstrated neuroprotective activity against N-methyl(R)salsolinol-induced apoptosis in human dopaminergic SH-SY5Y neuroblastoma cells through stabilization of mitochondrial membrane potential and upregulation of anti-apoptotic Bcl-2 protein expression. The compound upregulates synthesis and secretion of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and glial cell line-derived neurotrophic factor (GDNF) in cultured mouse astrocytes, with NGF secretion increased up to 120-fold over control at optimal concentrations. In longevity studies conducted by Knoll and Miklya, subcutaneous administration of BPAP at 0.0001 mg/kg three times weekly from the 10th week of life significantly extended lifespan in male Wistar rats (P < 0.02) and suppressed spontaneous fibromyxosarcoma manifestation from 50 percent (saline controls) to 20 percent (P < 0.001). Pharmacokinetic characterization in rats indicates oral bioavailability with peak plasma levels at 30 to 60 minutes, a secondary peak at approximately 4 hours consistent with enterohepatic recirculation, a terminal elimination half-life of 5.5 to 5.8 hours, blood-brain barrier penetration with distribution to multiple brain regions, and predominantly urinary excretion with greater than 90 percent recovery in excreta within 72 hours. No human clinical trials have been conducted with BPAP as of the date of this monograph. The compound remains an investigational research tool with potential therapeutic relevance to neurodegenerative disease (Parkinson's disease, Alzheimer's disease), depression, and age-related cognitive decline. This monograph reviews the chemistry, synthesis, and stereochemistry of BPAP; the enhancer pharmacology in molecular and neurochemical detail including the TAAR1 mechanism; comprehensive preclinical pharmacokinetics; the neuroprotective, neurotrophic, and longevity evidence; sourcing and quality verification considerations; reconstitution and handling; stack-interaction considerations; adverse-event and safety signal; and a comparative assessment of five monoaminergic activity enhancer and related catecholaminergic compounds against BPAP on five competency standards.

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  • GDF11

    Transforming growth factor beta superfamily secreted signaling protein (activin/myostatin subclass)

    A TGF-beta superfamily ligand identified as a candidate circulating rejuvenation factor through heterochronic parabiosis experiments, with reported effects on cardiac hypertrophy, skeletal muscle regeneration, cerebrovascular remodeling, and neurogenesis in aged mice, now subject to significant controversy regarding assay specificity, dose-response boundaries, and translational viability.

    Abstract

    Growth differentiation factor 11 (GDF11), also designated bone morphogenetic protein 11 (BMP-11), is a secreted homodimeric signaling protein of the transforming growth factor beta (TGF-beta) superfamily that signals through activin type II receptors (ActRIIA and ActRIIB) and type I receptors ALK4 and ALK5 to activate the canonical SMAD2/3 transcription factor pathway. GDF11 shares approximately 90 percent amino acid identity in its mature signaling domain with myostatin (GDF8), the well-characterized negative regulator of skeletal muscle mass, and is regulated by the same extracellular inhibitors (follistatin, FSTL3, WFIKKN1/2) and the same tolloid-family metalloproteinase activation mechanism. The protein is synthesized as a 407-amino-acid precursor that undergoes sequential proteolytic processing: signal peptide removal, furin-mediated cleavage of the prodomain, and tolloid-dependent liberation of the active mature homodimer from the latent prodomain complex.

    GDF11 became one of the most intensely debated molecules in modern aging biology following landmark publications from the laboratory of Amy Wagers and Richard Lee at Harvard between 2013 and 2014. Using heterochronic parabiosis and systemic delivery of recombinant GDF11, these investigators reported that GDF11 levels decline with age in mice and that restoration of youthful GDF11 concentrations reverses age-related cardiac hypertrophy (Loffredo et al., 2013), restores skeletal muscle stem cell function and enhances muscle repair (Sinha et al., 2014), and induces cerebrovascular remodeling with increased neurogenesis and improved olfactory discrimination in aged animals (Katsimpardi et al., 2014). These findings generated exceptional scientific and public interest, with GDF11 described in the popular press as a circulating “youth factor” or “rejuvenation protein.”

    The initial claims became intensely controversial when independent laboratories demonstrated that the original immunoassays could not reliably distinguish GDF11 from its close homolog myostatin (Egerman et al., 2015; Smith et al., 2015), that circulating GDF11/myostatin immunoreactivity may increase rather than decrease with age when measured by more specific methods, and that supraphysiological recombinant GDF11 administration inhibits rather than promotes skeletal muscle regeneration and can induce severe cachexia, muscle wasting, and premature death in mice (Egerman et al., 2015; Harper et al., 2016; Hammers et al., 2017; Jones et al., 2018). These contradictory findings have not been fully resolved. The current scientific consensus recognizes GDF11 as a biologically important developmental signaling molecule with plausible but unproven therapeutic potential in aging, and regards the magnitude and direction of its age-related changes and the safety window for exogenous administration as open questions requiring further investigation with rigorously validated, myostatin-discriminating assays.

    GDF11 is not approved as a therapeutic agent by any regulatory authority. Sotatercept, an ActRIIA-Fc fusion protein that sequesters GDF11 along with activin A and myostatin, was approved by the United States Food and Drug Administration in March 2024 for pulmonary arterial hypertension, representing the first clinical validation of pharmacological modulation of GDF11-class signaling. No recombinant GDF11 product has entered human clinical trials. The compound is available as a research-grade recombinant protein from multiple commercial suppliers for in vitro and preclinical investigation. This monograph reviews the molecular biology, processing, and signaling of GDF11; the discovery and development history including the parabiosis experiments and the subsequent replication controversy; the preclinical pharmacology across cardiac, skeletal muscle, neurological, and oncological domains; the limited pharmacokinetic characterization; the sourcing, reconstitution, and quality verification considerations for research-grade material; the adverse-event and safety signal with emphasis on the cachexia and muscle-wasting toxicity at supraphysiological doses; and a structured comparative assessment of five related TGF-beta superfamily ligands and modulators against GDF11 on five competency standards.

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  • Tadalafil

    Selective phosphodiesterase type 5 (PDE5) inhibitor with secondary PDE11 activity

    A long-acting beta-carboline-derived cyclic GMP phosphodiesterase inhibitor developed by ICOS and Eli Lilly for erectile dysfunction, subsequently approved for benign prostatic hyperplasia and pulmonary arterial hypertension, distinguished from other PDE5 inhibitors by a 17.5-hour plasma half-life, food-independent absorption, and emerging preclinical interest in neuroprotection and cognitive enhancement.

    Abstract

    Tadalafil is a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5), approved by the United States Food and Drug Administration for the treatment of erectile dysfunction (ED), the signs and symptoms of benign prostatic hyperplasia (BPH), and pulmonary arterial hypertension (PAH). Structurally a beta-carboline (pyrazinopyridoindole) derivative bearing a methylenedioxyphenyl substituent, tadalafil is chemically and pharmacologically distinct from the pyrimidinone-based PDE5 inhibitors sildenafil and vardenafil. The compound was originally synthesized at ICOS Corporation as IC351, advanced through clinical development in a joint venture with Eli Lilly and Company (Lilly ICOS LLC), and received its first regulatory approval in the European Union in November 2002 and in the United States in November 2003 under the trade name Cialis for the on-demand treatment of ED at 10 mg and 20 mg oral doses [1, 2].

    The defining pharmacokinetic feature of tadalafil is its prolonged plasma elimination half-life of approximately 17.5 hours, roughly three to five times longer than the half-lives of sildenafil (3 to 5 hours) and vardenafil (4 to 5 hours), enabling a clinically meaningful therapeutic window of 24 to 36 hours from a single oral dose and supporting a once-daily 2.5 mg or 5 mg dosing regimen approved for both ED and BPH [3, 4]. Absorption is not affected by food, a further distinction from sildenafil and vardenafil, whose absorption is delayed by high-fat meals. Tadalafil is metabolized predominantly by hepatic cytochrome P450 3A4 (CYP3A4) to the pharmacologically inactive methylcatechol glucuronide conjugate; approximately 61 percent of an administered dose is excreted in feces and 36 percent in urine [5].

    The molecular mechanism is inhibition of PDE5, the enzyme responsible for hydrolysis of cGMP in vascular smooth muscle. In the corpus cavernosum, nitric oxide released during sexual stimulation activates soluble guanylate cyclase, which synthesizes cGMP from guanosine triphosphate; cGMP in turn activates protein kinase G, producing smooth muscle relaxation, vasodilation, and penile erection. By preventing cGMP degradation, tadalafil amplifies and sustains the nitric oxide signaling cascade. The same mechanism operates in the pulmonary vasculature (where PDE5 inhibition reduces pulmonary arterial pressure) and in the smooth muscle of the prostate, bladder neck, and urethra (where PDE5 inhibition alleviates lower urinary tract symptoms associated with BPH) [6, 7]. Tadalafil is more than 10,000-fold selective for PDE5 over PDE3 (cardiovascular), approximately 700-fold selective over PDE6 (retinal), but only approximately 40-fold selective over PDE11A, a dual-specificity phosphodiesterase expressed in skeletal muscle, prostate, testes, and other tissues. The relatively low PDE5/PDE11 selectivity ratio is the presumed molecular basis for the back pain and myalgia adverse events that occur at higher frequency with tadalafil than with the other PDE5 inhibitors [8, 9].

    Clinical efficacy in ED has been established across multiple randomized, double-blind, placebo-controlled trials enrolling populations with mild through severe dysfunction, with overall response rates of 60 to 70 percent on validated questionnaires. The 40 mg once-daily dose for PAH produced a statistically significant 33-meter improvement in six-minute walk distance over placebo in the PHIRST registration trial [10]. The 5 mg once-daily dose for BPH produced a statistically significant improvement in International Prostate Symptom Score (IPSS) of approximately 2 points over placebo across four pivotal 12-week trials [11]. Common adverse events include headache (approximately 15 percent at 20 mg), dyspepsia (approximately 10 percent), back pain (approximately 6 percent), myalgia (approximately 4 percent), nasal congestion, and flushing. The compound is absolutely contraindicated with organic nitrates (the combination produces severe, potentially fatal hypotension) and with soluble guanylate cyclase stimulators [12, 13]. Rare but serious postmarketing signals include nonarteritic anterior ischemic optic neuropathy (NAION), sudden sensorineural hearing loss, and priapism. The compound is not recommended in patients with recent myocardial infarction, unstable angina, uncontrolled hypertension, or in patients in whom sexual activity is medically inadvisable.

    This monograph documents the chemistry, synthesis, and stereochemistry of tadalafil; the PDE5 inhibitory mechanism in molecular and physiological detail; the comprehensive human pharmacokinetic record; the preclinical pharmacology across vascular, urological, pulmonary, and neuroprotective domains; the clinical evidence base for all approved and investigational indications; sourcing and quality verification considerations; reconstitution and handling; stack-interaction implications for concurrent pharmacotherapy; adverse-event and safety signal characterization; and a structured comparative assessment of five PDE5 inhibitor alternatives (sildenafil, vardenafil, avanafil, mirodenafil, udenafil) against tadalafil on five competency standards: novelty, effect size, promising potential, side-effect profile, and overall validation.

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  • Urolithin-B

    Dibenzopyranone gut microbiota metabolite derived from ellagitannin catabolism with anabolic, anti-inflammatory, antioxidant, and neuroprotective activity

    A monohydroxylated dibenzo[b,d]pyran-6-one produced by colonic microflora from dietary ellagitannins and ellagic acid, distinguished from the structurally related urolithin A by selective promotion of skeletal muscle protein synthesis via androgen receptor and mTORC1 signaling, and by protective activity against islet amyloid polypeptide proteotoxicity.

    Abstract

    Urolithin B (3-hydroxy-6H-dibenzo[b,d]pyran-6-one; CAS 1139-83-9) is one of the two principal terminal metabolites generated by human colonic microflora from dietary ellagitannins and ellagic acid, polyphenolic compounds abundant in pomegranates, walnuts, raspberries, strawberries, and certain tree nuts. Unlike its dihydroxylated isomer urolithin A (3,8-dihydroxyurolithin), which has advanced into human clinical trials primarily on the basis of mitophagy induction and mitochondrial quality control, urolithin B is distinguished by a pharmacological profile centered on skeletal muscle anabolism, neuroprotection through PI3K/Akt survival signaling, anti-inflammatory activity through NF-kappaB and NLRP3 inflammasome suppression, and a unique capacity to attenuate islet amyloid polypeptide (IAPP) proteotoxicity relevant to type 2 diabetes pathogenesis. The skeletal muscle activity, formally characterized by Rodriguez et al. (2017), demonstrated that urolithin B at 15 micromolar enhanced C2C12 myotube protein synthesis by 96.1 percent, increased myotube diameter and fusion index, suppressed the ubiquitin-proteasome degradation pathway, and operated through an androgen receptor to mTORC1 signaling axis independent of Akt phosphorylation. In vivo, 28-day subcutaneous delivery at 10 micrograms per day produced 11.9 percent increases in tibialis anterior muscle fiber cross-sectional area and significant preservation of muscle mass in denervation-induced atrophy models. The neuroprotective profile, characterized by Chen et al. (2021) in D-galactose-induced aging mice, demonstrated dose-dependent rescue of spatial and working memory deficits at oral doses of 50 to 150 mg/kg/day for 8 weeks, mediated by PI3K/Akt pathway activation, inhibition of JNK/p38 apoptotic signaling, suppression of cytochrome c mitochondrial release, and restoration of hippocampal synaptic density markers PSD95 and synapsin I. Anti-inflammatory mechanisms, characterized in BV2 microglial cells by Lee et al. (2019), include suppression of NF-kappaB activation through reduced IkappaBalpha phosphorylation and degradation, attenuation of JNK, ERK, and Akt phosphorylation, enhancement of AMPK phosphorylation, and upregulation of heme oxygenase-1 through Nrf2/ARE signaling. Anticancer activity has been demonstrated in hepatocellular carcinoma (through Wnt/beta-catenin inactivation), osteosarcoma (G2/M arrest and MMP-2/-9 targeting), bladder cancer, leukemia, triple-negative breast cancer, and esophageal cancer cell lines. Bone-protective activity was reported in ovariectomy-induced osteoporosis models through inhibition of osteoclast formation via ERK/NF-kappaB suppression. The compound is produced endogenously only by individuals with the urolithin metabotype B (UM-B) gut microbiota profile, estimated at approximately 10 to 50 percent of the population depending on ethnicity and dietary pattern. Urolithin B undergoes extensive hepatic phase II conjugation to glucuronide and sulfate metabolites; circulating total urolithin concentrations in UM-B individuals following ellagitannin consumption range from 0.003 to 5.2 micromolar, with urinary excretion reaching up to 50 micromolar. No human clinical trials of exogenous urolithin B supplementation have been completed as of monograph preparation. The compound is available as a research-grade preparation from multiple chemical suppliers at greater than 95 percent purity. This monograph reviews the chemistry, biosynthesis, and structural class of urolithin B; the molecular pharmacology across muscle, neuronal, inflammatory, metabolic, and oncologic systems; the preclinical evidence base; the pharmacokinetic and metabotype considerations; sourcing and quality verification; reconstitution and handling; stack interactions; adverse events and safety signals; and a comparative assessment of five structurally or functionally related compounds against urolithin B on five competency standards.

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  • Roxadustat

    Plain-language summaryIntrigue 70 / 100

    Roxadustat is a small-molecule alternative to injected EPO for kidney disease anemia. Instead of replacing EPO, it blocks the prolyl hydroxylase enzymes that normally tag the HIF transcription factor for destruction in oxygenated tissue. Stabilizing HIF makes the body think it is hypoxic and triggers endogenous EPO transcription plus genes that improve iron utilization. Approved in China and the EU for chronic kidney disease anemia, but the FDA declined to approve it in 2021 over cardiovascular safety concerns. The HIF-PHI mechanism is genuinely novel and the oral route is a major patient convenience over injected EPO. 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.

    Hypoxia-inducible factor prolyl hydroxylase inhibitor (HIF-PHI) and 2-oxoglutarate analog

    A first-in-class oral hypoxia-inducible factor prolyl hydroxylase inhibitor developed by FibroGen for the treatment of anemia in chronic kidney disease, distinguished from conventional erythropoiesis-stimulating agents by its mechanism of HIF-alpha stabilization, endogenous erythropoietin induction, hepcidin suppression, and improved iron homeostasis.

    Abstract

    Roxadustat (FG-4592), the N-[(4-hydroxy-1-methyl-7-phenoxyisoquinolin-3-yl)carbonyl]glycine derivative and first-in-class hypoxia-inducible factor prolyl hydroxylase inhibitor (HIF-PHI) to receive regulatory approval worldwide, is an orally bioavailable small molecule developed by FibroGen, Inc. for the treatment of anemia associated with chronic kidney disease (CKD) in both dialysis-dependent and non-dialysis-dependent patient populations. The compound acts by competitively inhibiting the three isoforms of prolyl hydroxylase domain enzymes (PHD1, PHD2, PHD3) that, under normoxic conditions, hydroxylate proline residues on the oxygen-dependent degradation domain of hypoxia-inducible factor alpha subunits (HIF-1alpha and HIF-2alpha), thereby targeting them for von Hippel-Lindau (VHL) E3 ubiquitin ligase-mediated proteasomal degradation. By reversibly occupying the 2-oxoglutarate binding pocket of the PHD enzymes, roxadustat stabilizes HIF-alpha, permitting its nuclear translocation, heterodimerization with HIF-beta (ARNT), and transcriptional activation of hypoxia-responsive element (HRE)-containing target genes. The principal therapeutic consequence is a dose-dependent, transient elevation of endogenous erythropoietin (EPO) production that remains within or near the physiological range, in contrast to the supraphysiological EPO concentrations produced by injectable erythropoiesis-stimulating agents (ESAs). In addition to EPO induction, roxadustat suppresses hepatic hepcidin expression, upregulates duodenal ferroportin and divalent metal transporter 1 (DMT1), increases transferrin receptor expression, and thereby improves iron absorption, mobilization, and utilization, an effect of particular clinical relevance in the iron-restricted erythropoiesis commonly observed in CKD patients with chronic inflammation. Roxadustat received its first global approval in China in December 2018 for dialysis-dependent CKD anemia, followed by approvals in Japan (2019, Astellas Pharma, marketed as Evrenzo), the European Union (August 2021, European Commission), South Korea, and Chile. In the United States, the Cardiovascular and Renal Drugs Advisory Committee of the Food and Drug Administration voted against approval in July 2021, citing unresolved cardiovascular safety signals (including increased rates of vascular access thrombosis and deep venous thrombosis in dialysis-dependent populations relative to epoetin alfa) and concerns regarding data integrity in the sponsor’s cardiovascular safety analyses. A large Phase 3 clinical program encompassing the ALPS, ANDES, OLYMPUS, ROCKIES, SIERRAS, HIMALAYAS, and PYRENEES trials demonstrated non-inferiority or superiority to placebo and non-inferiority to epoetin alfa for hemoglobin correction and maintenance across CKD populations, with pooled analyses in incident dialysis patients suggesting a 30 percent reduction in major adverse cardiovascular events (MACE) relative to epoetin alfa. Pharmacokinetics are characterized by rapid oral absorption (Tmax approximately 1 to 2 hours), high plasma protein binding (approximately 99 percent), hepatic metabolism predominantly through CYP2C8 oxidation and UGT1A9 glucuronidation, and an elimination half-life of approximately 12 to 15 hours in CKD patients. Clinically significant drug-drug interactions include increased exposure with CYP2C8 inhibitors (gemfibrozil), reduced absorption with phosphate binders (sevelamer, calcium acetate), and inhibition of BCRP and OATP1B1 transporters leading to elevated statin exposures when co-administered. Beyond anemia, preclinical and early clinical evidence suggests potential renoprotective, anti-inflammatory, and cardioprotective properties mediated through HIF-dependent pathways, including protection against ischemia-reperfusion injury, suppression of NF-kappaB-driven inflammatory cytokines, and modulation of lipid metabolism. This monograph reviews the chemistry, synthesis, and structural pharmacology of roxadustat; the molecular mechanism of HIF-PHD inhibition in biochemical and cellular detail; the comprehensive human pharmacokinetic record; preclinical pharmacology across renal, inflammatory, and metabolic models; the clinical evidence base from the global Phase 3 program; sourcing and quality verification considerations; reconstitution and handling; drug interaction and combination considerations; adverse-event and safety signals including the cardiovascular and thrombotic concerns that limited United States approval; and a comparative assessment of five HIF-PHI class members (daprodustat, vadadustat, molidustat, enarodustat, desidustat) against roxadustat on five competency standards.

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