Category: Uncategorized

  • SBT-272

    Mitochondria-targeted cardiolipin-stabilizing peptidomimetic with enhanced central nervous system penetration

    A next-generation cardiolipin-binding peptidomimetic developed by Stealth BioTherapeutics as a brain-penetrant successor to elamipretide (SS-31), designed to restore mitochondrial structure and function in neurodegenerative disease with demonstrated preclinical neuroprotection in models of amyotrophic lateral sclerosis, frontotemporal dementia, Parkinson’s disease, Huntington’s disease, and ischemic stroke.

    Abstract

    SBT-272, also designated bevemipretide (International Nonproprietary Name), is a clinical-stage mitochondria-targeted peptidomimetic small molecule developed by Stealth BioTherapeutics as a structurally optimized successor to elamipretide (SS-31, MTP-131, Bendavia). The compound selectively binds cardiolipin, a diphosphatidylglycerol lipid exclusively localized to the inner mitochondrial membrane, where it stabilizes the organization of electron transport chain complexes into supercomplexes (respirasomes), promotes efficient oxidative phosphorylation, reduces mitochondrial reactive oxygen species generation, and prevents the cytochrome c/cardiolipin peroxidase activity that initiates apoptotic signaling. Relative to the first-generation elamipretide scaffold, SBT-272 demonstrates higher mitochondrial uptake, greater brain accumulation following subcutaneous administration, and improved systemic bioavailability in preclinical species, properties that position the compound for neurodegenerative disease indications where central nervous system exposure is a critical determinant of therapeutic effect.

    The preclinical pharmacology of SBT-272 encompasses multiple neurodegenerative disease models. In TDP-43 mutant upper motor neuron cultures derived from the prpTDP-43(A315T) transgenic mouse, SBT-272 restored mitochondrial structural integrity, recovered mitochondrial motility in a dose-dependent manner, and improved axon outgrowth, a functional indicator of neuronal health, with effects superior to those of edaravone and AMX0035 in the same system [1]. Chronic in vivo treatment for sixty days in the same model significantly reduced astrogliosis, microgliosis, and TDP-43 pathology in the motor cortex [1]. In the SOD1(G93A) transgenic mouse model of amyotrophic lateral sclerosis, high-dose SBT-272 (5.0 mg/kg/day intraperitoneal) delayed neurological symptom onset and significantly extended lifespan in male mice [2]. In an alpha-synucleinopathy mouse model of Parkinson’s disease, daily subcutaneous SBT-272 attenuated dopaminergic neuron loss, reduced pathological alpha-synuclein burden, and suppressed neuroinflammatory markers [3]. Additional preclinical neuroprotective activity has been reported in models of frontotemporal lobar dementia, Huntington’s disease, and ischemic stroke [4].

    Clinical development has advanced through a Phase 1 double-blind, placebo-controlled study in healthy volunteers evaluating subcutaneous SBT-272 at single ascending doses of 5 to 60 mg and multiple ascending doses of 20, 40, and 60 mg daily for 7 days [5]. Interim results demonstrated a pharmacokinetic profile consistent with preclinical allometric scaling predictions, plasma and projected brain exposures at doses anticipated to reach therapeutic concentrations based on preclinical efficacy thresholds, and a safety profile in which the most commonly reported adverse event was mild-to-moderate injection site reaction resolving within approximately 4 hours of dosing [5]. The United States Food and Drug Administration granted Orphan Drug Designation for SBT-272 for the treatment of amyotrophic lateral sclerosis in 2022 [4]. A separate development program for topical ocular bevemipretide (eye drops) in dry age-related macular degeneration has advanced through preclinical studies demonstrating approximately 4- to 6-fold higher retinal tissue concentrations compared to elamipretide, with a 13-week GLP toxicology study informing Phase 1 trial design [6, 7].

    This monograph reviews the chemistry, structural class, and synthesis of SBT-272; the cardiolipin-stabilization mechanism at the inner mitochondrial membrane; the pharmacokinetic profile including brain penetration; the preclinical pharmacology across ALS, Parkinson’s disease, and additional neurodegenerative models; the Phase 1 clinical evidence base; sourcing and quality verification considerations; reconstitution and handling; stack-interaction implications; adverse-event signal; and a comparative assessment of five mitochondria-targeted or neuroprotective candidates against SBT-272 on five competency standards (novelty, effect size, promising potential, side-effect profile, and overall validation).

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  • Tabernanthalog

    Non-hallucinogenic ibogaine analog and serotonergic psychoplastogen with 5-HT2A partial agonist activity promoting structural neuroplasticity

    A rationally designed, water-soluble, non-hallucinogenic analog of ibogaine engineered through function-oriented synthesis to retain psychoplastogenic neuroplasticity and preclinical antidepressant and anti-addictive activity while eliminating the cardiotoxicity and hallucinogenic liability of the parent alkaloid.

    Abstract

    Tabernanthalog (TBG, DLX-007) is a synthetic, water-soluble analog of the indole alkaloid ibogaine, first reported by Cameron et al. in a 2020 publication in Nature from the Olson laboratory at the University of California, Davis. The compound was engineered through function-oriented synthesis to isolate the therapeutic pharmacophore of ibogaine while eliminating two liabilities that have prevented clinical development of the parent alkaloid: blockade of the human ether-a-go-go-related gene (hERG) potassium channel (the basis of ibogaine-associated QT prolongation and fatal cardiac arrhythmia) and activation of hallucinogenic signaling cascades downstream of the serotonin 5-HT2A receptor. Tabernanthalog retains the capacity to promote rapid, sustained structural neuroplasticity in cortical neurons, including dendritic arborization and spinogenesis in the prefrontal cortex, through activation of the 5-HT2A receptor and downstream TrkB, mTOR, and AMPA receptor signaling pathways. A 2025 publication in Nature Neuroscience by Aarrestad et al. demonstrated that tabernanthalog achieves this neuroplasticity without inducing the immediate glutamate burst or the immediate early gene (IEG) activation that characterize classical hallucinogenic psychedelics, establishing a dissociation between psychoplastogenic structural remodeling and the acute transcriptional programs previously considered prerequisite. In behavioral pharmacology, tabernanthalog does not produce the mouse head-twitch response, the standard behavioral proxy for hallucinogenic activity, confirming its non-hallucinogenic profile. Preclinical efficacy has been demonstrated across multiple disease-relevant models: a single dose reduces immobility in the forced swim test (antidepressant-like activity); a single dose restores functional neural circuits, including dendritic spine density and sensory processing, disrupted by unpredictable mild stress in mice (Lu et al., Molecular Psychiatry 2021); a single dose reduces heroin self-administration in rats and alcohol binge drinking in mice; and tabernanthalog reduces motivation for both heroin and alcohol in a polydrug use model with effects persisting up to 14 days after treatment (Heinsbroek et al., 2023). The molecular pharmacology of tabernanthalog extends beyond 5-HT2A partial agonism to include antagonism at the 5-HT2B receptor, agonism at 5-HT1B, 5-HT1F, 5-HT2C, and 5-HT6 receptors, inhibition of monoamine oxidase A, activity at the alpha-2A adrenergic receptor and the serotonin transporter, and inhibition of alpha-7 and alpha-9/alpha-10 nicotinic acetylcholine receptors at low-micromolar concentrations. The compound does not interact significantly with opioid receptors, the NMDA receptor, or the hERG potassium channel. Tabernanthalog is prepared in a single synthetic step from commercially available precursors, is freely water-soluble as the fumarate salt, and has a molecular weight of 230.31 g/mol (free base). Despite strong preclinical validation and assignment of the development code DLX-007 by Delix Therapeutics, the compound has not entered human clinical trials as of May 2026; the company’s lead clinical candidate is the structurally related psychoplastogen zalsupindole (DLX-001). This monograph reviews the chemistry, synthesis, and structure-activity relationships of tabernanthalog; the multi-target molecular pharmacology in receptor-level and signaling-pathway detail; the available pharmacokinetic characterization; the preclinical efficacy data across depression, stress, addiction, pain, and cognitive models; the clinical development status; sourcing and quality verification considerations; reconstitution and handling; stack-interaction implications; the adverse-event and safety profile; and a comparative assessment of five alternative psychoplastogens and ibogaine analogs against tabernanthalog on five competency standards.

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  • Cebranopadol

    Mixed nociceptin/orphanin FQ peptide (NOP) receptor and opioid receptor agonist analgesic

    A first-in-class spiro-indole analgesic with near-equipotent agonism at nociceptin/orphanin FQ peptide and classical opioid receptors, developed by Grunenthal and advanced by Tris Pharma through Phase 3 acute pain trials, distinguished from conventional opioids by NOP receptor-mediated attenuation of respiratory depression and abuse liability.

    Abstract

    Cebranopadol (GRT-6005, PRK-101, TRN-228) is a first-in-class small-molecule analgesic that acts as a high-affinity agonist at the nociceptin/orphanin FQ peptide (NOP) receptor and at the three classical opioid receptor subtypes (mu, kappa, and delta), with near-equipotent activation of the NOP and mu-opioid receptors at low-nanomolar concentrations. The compound was discovered at Grunenthal GmbH in Aachen, Germany, and first described in patent literature in 2002. Scientific characterization beginning in 2013 established cebranopadol as a spiro[cyclohexane-dihydropyrano[3,4-b]indole] derivative with binding affinities (Ki) of 0.7 nM at the human mu-opioid receptor, 0.9 nM at the human NOP receptor, 2.6 nM at the kappa-opioid receptor, and 18 nM at the delta-opioid receptor, and with functional potencies (EC50) of 1.2 nM (mu), 13 nM (NOP), 17 nM (kappa), and 110 nM (delta) in calcium mobilization assays, yielding a rank order of potency mu approximately equal to NOP, then kappa, then delta. The compound acts as a full agonist at the mu-opioid and delta-opioid receptors, a near-full agonist at the NOP receptor (89 percent relative efficacy), and a partial agonist at the kappa-opioid receptor (67 percent relative efficacy). A distinctive signaling feature is G-protein bias at the NOP receptor, where cebranopadol promotes G-protein coupling without measurable beta-arrestin 2 recruitment, while retaining full beta-arrestin 2 coupling at the mu-opioid receptor.

    The dual NOP and opioid receptor agonism produces a pharmacological profile that is differentiated from conventional mu-selective opioid analgesics in three respects: (1) enhanced relative potency in models of chronic neuropathic and inflammatory pain compared with acute nociceptive pain, with a seven-fold potency advantage in the mouse formalin test relative to the tail-withdrawal paradigm; (2) attenuation of opioid-type respiratory depression, with preclinical evidence of a ceiling effect on respiratory suppression attributable to the NOP receptor contribution; and (3) reduced abuse liability, demonstrated in a Phase 1 human abuse potential study showing less drug-liking and lower subjective effects relative to hydromorphone in non-dependent recreational opioid users, and in a separate study showing less abuse potential than tramadol and oxycodone. Additionally, preclinical studies demonstrated delayed analgesic tolerance development (26 days in cebranopadol-treated animals versus 11 days for morphine at equianalgesic doses in the chronic constriction injury model).

    Pharmacokinetics in humans are characterized by complete oral absorption with approximately 40 percent bioavailability reflecting first-pass hepatic metabolism, a late time to maximum plasma concentration (4 to 6 hours), a long terminal elimination half-life of 62 to 96 hours, and an operational half-life of approximately 24 hours supporting once-daily dosing. Steady-state plasma concentrations are achieved after approximately two weeks of daily administration, with an accumulation factor of approximately 2-fold and low peak-trough fluctuation (70 to 80 percent). Clearance is influenced by CYP2C9 phenotype, with poor and intermediate metabolizers showing reduced clearance relative to extensive metabolizers. The compound does not inhibit CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, or CYP3A4/5 at concentrations up to 250 nM, indicating a low potential for metabolic drug-drug interactions.

    Clinical development has encompassed more than 32 clinical trials involving more than 2,200 participants. A Phase 2 randomized, double-blind, placebo-controlled and active-controlled (tapentadol) trial in chronic low back pain (Christoph et al. 2017) demonstrated statistically significant and clinically relevant analgesic efficacy at doses of 200, 400, and 600 micrograms once daily over 14 weeks. A Phase 2a trial in postoperative acute pain demonstrated efficacy at 400 and 600 microgram doses. Two pivotal Phase 3 trials (ALLEVIATE-1, in post-abdominoplasty pain, and ALLEVIATE-2, in post-bunionectomy pain) met their primary efficacy endpoints, with cebranopadol 400 micrograms demonstrating significant reduction in pain intensity versus placebo. The ALLEVIATE-2 trial additionally showed that a higher proportion of cebranopadol-treated patients required no opioid rescue medication compared with placebo. Tris Pharma, which acquired worldwide rights to cebranopadol through its 2021 acquisition of Park Therapeutics, has announced plans for FDA submission. The compound is not yet approved by any regulatory authority and is not a scheduled controlled substance as of 2025. This monograph reviews the chemistry, synthesis, dual-receptor pharmacology, pharmacokinetics, preclinical and clinical evidence, sourcing, handling, stack interactions, safety profile, and a comparative assessment of five analgesic candidates against cebranopadol on five competency standards.

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  • Fish-Oil

    Marine-derived omega-3 polyunsaturated fatty acid complex, principally eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)

    A lipid extract of cold-water marine fish tissue containing the long-chain omega-3 polyunsaturated fatty acids eicosapentaenoic acid and docosahexaenoic acid, with established regulatory approval for severe hypertriglyceridemia and a broad but heterogeneous evidence base spanning cardiovascular risk reduction, systemic inflammation, mood disorders, and neurocognitive support.

    Abstract

    Fish oil is a complex lipid extract derived from the tissue of cold-water marine fish species (principally anchovy, sardine, mackerel, herring, and menhaden) and is the predominant dietary and supplemental source of the long-chain omega-3 polyunsaturated fatty acids eicosapentaenoic acid (EPA, C20:5n-3) and docosahexaenoic acid (DHA, C22:6n-3). These two fatty acids serve as precursors for specialized pro-resolving mediators (resolvins, protectins, maresins), compete with arachidonic acid for cyclooxygenase and lipoxygenase substrate pools to shift eicosanoid production from pro-inflammatory series-2 prostaglandins and series-4 leukotrienes toward less inflammatory or anti-inflammatory series-3 prostaglandins and series-5 leukotrienes, modulate cell membrane phospholipid composition and lipid raft organization, activate the anti-inflammatory transcription factor peroxisome proliferator-activated receptor gamma (PPARgamma), signal through the G protein-coupled receptor GPR120, and influence ion channel conductance and cardiac electrophysiology. The pharmacological interest in fish oil spans more than five decades, originating with the epidemiological observations of Bang and Dyerberg in Greenland Inuit populations in the early 1970s and progressing through multiple large-scale randomized controlled trials including GISSI-Prevenzione (1999), JELIS (2007), VITAL (2019), REDUCE-IT (2019), and STRENGTH (2020). Prescription omega-3 formulations have received regulatory approval from the United States Food and Drug Administration for the treatment of severe hypertriglyceridemia (triglycerides 500 mg/dL or greater): omega-3-acid ethyl esters (Lovaza, approved 2004), icosapent ethyl (Vascepa, approved 2012), and omega-3-carboxylic acids (Epanova, approved 2014). Icosapent ethyl, a purified EPA ethyl ester, received an expanded FDA indication in 2019 for cardiovascular risk reduction in statin-treated patients with elevated triglycerides and established cardiovascular disease or diabetes, based on the REDUCE-IT trial demonstrating a 25 percent relative risk reduction in major adverse cardiovascular events. The STRENGTH trial, which tested a combined EPA and DHA carboxylic acid formulation, was terminated early for futility with no cardiovascular benefit observed, generating ongoing debate regarding the differential efficacy of EPA-only versus EPA plus DHA preparations and the potential confounding role of mineral oil placebo in REDUCE-IT. Fish oil pharmacokinetics are governed by the chemical form of the omega-3 fatty acids (triglyceride, ethyl ester, free fatty acid, or phospholipid), with triglyceride and free fatty acid forms demonstrating superior bioavailability compared to ethyl esters, particularly under low-fat dietary conditions. Absorption requires pancreatic lipase-mediated hydrolysis and micellar solubilization; peak plasma EPA and DHA concentrations are achieved at approximately 5 to 8 hours post-dose, and steady-state tissue incorporation requires 4 to 12 weeks of daily supplementation. The safety profile of fish oil at standard supplemental doses (1 to 4 grams of EPA plus DHA daily) is generally favorable, with the principal adverse events being gastrointestinal discomfort, fishy eructation, and mild prolongation of bleeding time without clinically significant hemorrhage. At pharmacological doses (4 grams daily), meta-analyses of randomized controlled trials have identified a statistically significant increase in the risk of atrial fibrillation (approximately 24 percent relative risk increase), representing the most clinically consequential safety signal in the contemporary evidence base. This monograph reviews the chemical identification and compositional analysis of fish oil; the discovery and development history from the Greenland epidemiology through modern pharmaceutical registration; the molecular pharmacology of EPA and DHA across lipid mediator, transcription factor, membrane, and ion channel mechanisms; pharmacokinetics including formulation-dependent bioavailability; preclinical pharmacology in cardiovascular, inflammatory, and cognitive animal models; the clinical evidence base across cardiovascular, inflammatory, psychiatric, and neurocognitive indications; sourcing and quality verification; reconstitution and handling; stack interactions and combinations; adverse events and safety signals; and a comparative assessment of five alternative omega-3 sources (krill oil, algal oil, icosapent ethyl, flaxseed oil, and omega-3-carboxylic acids) against fish oil on five standards (bioavailability, clinical evidence base, safety profile, cost and accessibility, and overall validation).

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  • Isotretinoin

    First-generation retinoid (13-cis-retinoic acid) with sebosuppressive, pro-apoptotic, anti-keratinizing, and immunomodulatory activity

    A systemic retinoid derived from vitamin A, developed at Hoffmann-La Roche as a treatment for severe recalcitrant nodular acne, distinguished from other retinoids by potent sebaceous gland suppression through sebocyte apoptosis, intracellular isomerization to all-trans retinoic acid, and additional clinical utility in high-risk neuroblastoma maintenance therapy.

    Abstract

    Isotretinoin (13-cis-retinoic acid) is a first-generation retinoid and geometric isomer of all-trans retinoic acid (tretinoin) that was approved by the United States Food and Drug Administration on 7 May 1982 under the trade name Accutane for the treatment of severe recalcitrant nodular acne unresponsive to conventional therapies including systemic antibiotics. The compound remains the most effective single agent for severe cystic and nodulocystic acne, producing long-term remission or cure in approximately 85 percent of patients after a single course at cumulative doses of 120 to 150 mg/kg administered over 15 to 20 weeks [1, 2]. Unlike topical retinoids that act through direct binding to retinoic acid receptors (RARs) at the site of application, isotretinoin functions as a systemic pro-drug: despite exhibiting low intrinsic affinity for both RAR and retinoid X receptor (RXR) nuclear receptors, the compound undergoes intracellular isomerization to all-trans retinoic acid in sebocytes and other target tissues, with the active isomer then binding RARs and driving transcriptional programs that suppress sebogenesis, normalize follicular keratinization, and induce apoptosis in sebaceous gland cells [3, 4]. The four principal pharmacological actions that underwrite clinical efficacy in acne are: (a) marked reduction in sebaceous gland size and sebum production (up to 90 percent suppression), mediated by FoxO3a-dependent and TRAIL/caspase-mediated apoptosis of sebocytes; (b) normalization of aberrant follicular keratinization, reducing comedone formation; (c) indirect suppression of Cutibacterium acnes colonization secondary to the reduction in the lipid-rich sebaceous microenvironment; and (d) anti-inflammatory and immunomodulatory activity, including downregulation of Toll-like receptor 2 (TLR-2) signaling and NF-kappaB-dependent cytokine production in monocytes and keratinocytes [5, 6, 7].

    Pharmacokinetics are characterized by variable oral bioavailability that is markedly enhanced by co-administration with a high-fat meal (approximately twofold increase in area under the curve), extensive plasma protein binding (greater than 99.9 percent to albumin), hepatic metabolism principally through CYP2C8, CYP3A4, CYP2C9, and CYP2B6 to the major circulating metabolite 4-oxo-isotretinoin, and a terminal elimination half-life of 10 to 20 hours for the parent compound and up to 50 hours for the 4-oxo metabolite [8, 9]. The compound undergoes enterohepatic recirculation, contributing to sustained plasma concentrations during chronic dosing.

    Beyond acne, isotretinoin has established clinical utility in the maintenance therapy of high-risk neuroblastoma, where six months of post-consolidation oral isotretinoin (160 mg/m2/day in two divided doses for 14 days of each 28-day cycle) significantly improved event-free survival in the landmark Children’s Cancer Group (CCG-3891) randomized trial [10]. The compound has also been studied in disorders of keratinization (lamellar ichthyosis, Darier disease), rosacea, prevention of second primary tumors in head and neck squamous cell carcinoma, and glioblastoma multiforme, though these applications have not produced registrational-quality evidence sufficient for label expansion.

    The safety profile of isotretinoin is dominated by two categories of concern. The first and most clinically significant is teratogenicity: isotretinoin is classified as FDA Pregnancy Category X, with an estimated 20 to 35 percent risk of major congenital malformations in exposed pregnancies, including craniofacial, cardiovascular, thymic, and central nervous system defects [11]. This risk led to the implementation of the iPLEDGE Risk Evaluation and Mitigation Strategy (REMS) program in the United States in 2006, which mandates pregnancy testing, dual contraception, and monthly verification for all patients of childbearing potential [12]. The second category comprises mucocutaneous adverse effects (cheilitis, xerosis, epistaxis, conjunctival dryness) that are nearly universal at therapeutic doses and reflect the pharmacological suppression of sebaceous and meibomian gland function. Additional safety signals include dose-dependent hypertriglyceridemia, transaminase elevation, musculoskeletal complaints (myalgia, arthralgia), and a contested but pharmacovigilance-supported association with psychiatric adverse events including depression, though large epidemiological studies have not established a causal relationship [13, 14]. The association with inflammatory bowel disease has been examined in multiple studies with conflicting results; the most rigorous analyses suggest the incidence is extremely low and the causal link remains unproven [15].

    This monograph reviews the chemistry, synthesis, and stereochemistry of isotretinoin; the receptor pharmacology and intracellular isomerization mechanism; comprehensive human pharmacokinetics; the clinical evidence base across dermatological and oncological indications; sourcing and quality verification; reconstitution and handling; stack-interaction considerations for research applications; the adverse-event and safety profile including teratogenicity and the iPLEDGE REMS; and a comparative assessment of five alternative acne and retinoid agents against isotretinoin on five competency standards.

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  • LPH-5

    Selective serotonin 5-HT2A receptor partial agonist of the 2,5-dimethoxyphenylpiperidine structural class

    A conformationally restricted phenethylamine psychedelic developed at Lophora ApS as a highly selective 5-HT2A receptor partial agonist with robust and persistent antidepressant-like activity in rodent models, distinguished from classical psychedelics by pronounced subtype selectivity over the serotonin 5-HT2B and 5-HT2C receptors and currently in Phase 1 clinical evaluation for treatment-resistant depression.

    Abstract

    LPH-5, the (S)-enantiomer of 3-(2,5-dimethoxy-4-(trifluoromethyl)phenyl)piperidine and a conformationally restricted analog of the phenethylamine psychedelic 2C-TFM, is a potent and selective partial agonist of the serotonin 5-hydroxytryptamine type 2A (5-HT2A) receptor under clinical development for treatment-resistant depression and potentially other neuropsychiatric indications. First disclosed in a 2021 patent assigned to Lophora ApS and characterized in the peer-reviewed literature by Marcher-Rorsted et al. (2024) in the Journal of Medicinal Chemistry, LPH-5 emerged from a systematic structure-activity relationship exploration of 2,5-dimethoxyphenylpiperidines in which cyclization of the flexible phenethylamine chain into a piperidine ring, combined with the 4-trifluoromethyl substituent, produced a compound with low-nanomolar 5-HT2A receptor binding affinity (Ki 1.3 nM against [125I]DOI), potent functional partial agonism in calcium mobilization assays (EC50 3.2 nM, Emax approximately 92 percent of the serotonin maximum at the 5-HT2A receptor), and approximately 60-fold functional selectivity for 5-HT2A over the 5-HT2B receptor, with no measurable agonist activity at the 5-HT2C receptor at concentrations up to 30 micromolar in receptor internalization assays. This selectivity profile distinguishes LPH-5 from classical serotonergic psychedelics such as psilocin, lysergic acid diethylamide, and N,N-dimethyltryptamine, all of which activate the 5-HT2B and 5-HT2C receptors at therapeutically relevant concentrations, and from the parent compound 2C-TFM, which retains substantial 5-HT2C agonist activity.

    In preclinical pharmacology, LPH-5 dose-dependently induces the head-twitch response in rodents, a behavioral correlate of 5-HT2A receptor activation and a proxy for psychedelic potential, confirming central target engagement after systemic administration. The compound produces robust acute and persistent antidepressant-like effects in the rat forced swim test, with reduction in immobility observed both at 24 hours and at 7 days after a single administration, a temporal profile consistent with the sustained antidepressant responses reported in clinical trials of psilocybin. The stereochemistry is critical: the (S)-enantiomer (designated the eutomer) is consistently more potent at the 5-HT2A receptor and more selective against the 5-HT2C receptor than the corresponding (R)-distomer across the entire 2,5-dimethoxyphenylpiperidine series. Absolute configuration was confirmed by X-ray crystallography. Physicochemical properties are favorable for central nervous system drug development, with a LogP of 3.45, high membrane permeability (MDR1-MDCKII efflux ratio 0.94), and ligand efficiency metrics (LE 0.6, LLE 5) that position the compound in the optimal drug-like space.

    Preclinical toxicology studies completed at Lophora reported no toxicology or histopathology findings, and all chemistry, manufacturing, and controls activities were completed by 2022. The European Medicines Agency authorized a Phase 1 first-in-human clinical trial in September 2024. The trial, a randomized placebo-controlled single- and multiple-ascending-dose study in healthy volunteers conducted at Biotrial in Rennes, France, began dosing subjects in May 2025, with topline results expected in the fourth quarter of 2025. LPH-5 is designed for use in psychedelic-assisted psychotherapy and represents a pharmacological strategy in which the therapeutic benefits of classical psychedelics are pursued through a compound with improved receptor subtype selectivity, reduced 5-HT2B-associated cardiac risk, and a defined stereochemical identity. This monograph reviews the chemistry, stereochemistry, and structure-activity relationships of LPH-5; the in vitro and in vivo pharmacology at serotonin receptor subtypes; the preclinical behavioral pharmacology; the development history and clinical trajectory; sourcing, reconstitution, and handling considerations for laboratory use; stack interactions; adverse-event expectations; and a structured comparative assessment of five alternative 5-HT2A receptor agonists (psilocybin/psilocin, 25CN-NBOH, DOI, LSD, and the non-hallucinogenic analog tabernanthalog) against LPH-5 on five competency standards.

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  • 25CN-NBOH

    Selective serotonin 5-HT2A receptor agonist of the N-benzyl phenethylamine (NBOH) structural class

    A high-affinity, brain-penetrant N-(2-hydroxybenzyl) phenethylamine developed at the University of Copenhagen as the most selective commercially available 5-HT2A receptor agonist tool compound, distinguished from classical serotonergic psychedelics by exceptional subtype selectivity and from the NBOMe series by a superior safety margin.

    Abstract

    25CN-NBOH (4-[2-[(2-hydroxyphenyl)methylamino]ethyl]-2,5-dimethoxybenzonitrile) is a synthetic phenethylamine of the N-benzyl-2-hydroxybenzyl (NBOH) structural class, first reported in 2014 by Hansen and colleagues at the University of Copenhagen as a potent and highly selective agonist of the serotonin 5-HT2A receptor. With a binding affinity (Ki) of approximately 0.81 to 1.32 nanomolar at the human 5-HT2A receptor and 52- to 100-fold selectivity over the closely related 5-HT2C receptor, 25CN-NBOH represents one of the most 5-HT2A-selective agonists described in the published literature and the most selective commercially available tool compound for interrogation of 5-HT2A receptor function in vitro and in vivo.

    The compound occupies a distinctive pharmacological niche. Unlike psilocybin, lysergic acid diethylamide (LSD), and N,N-dimethyltryptamine, which activate multiple serotonin receptor subtypes and, in the case of LSD, dopamine and adrenergic receptors, 25CN-NBOH provides a pharmacological lever with which 5-HT2A-mediated effects can be isolated from confounding receptor contributions. Unlike the structurally related NBOMe series (25I-NBOMe, 25C-NBOMe, 25B-NBOMe), which carry an N-methoxybenzyl substituent and have been associated with serious toxicity and fatalities in recreational contexts, 25CN-NBOH carries an N-(2-hydroxybenzyl) group that confers a more favorable preclinical safety profile and improved metabolic stability.

    The pharmacological characterization of 25CN-NBOH has advanced substantially since 2014. A tritiated radioligand ([3H]25CN-NBOH) has been synthesized and validated for equilibrium and kinetic binding assays and for autoradiography in rat brain, providing high-resolution mapping of 5-HT2A receptor distribution. The cryo-electron microscopy structure of 25CN-NBOH bound to the human 5-HT2A receptor in complex with a mini-Gaq heterotrimer, solved at 3.27 angstrom resolution by Kim et al. (2020) and published in Cell, provided the first atomic-resolution view of a hallucinogen-activated serotonin receptor and has become a foundational reference for structure-based drug design in the serotonergic psychedelic field. Structure-activity relationship studies have mapped the 2-prime and 3-prime positions of the N-benzyl ring as critical determinants of 5-HT2A agonist activity and have identified conformationally restrained analogs and beta-arrestin-biased derivatives that enable pathway-selective pharmacology.

    Preclinical pharmacology in rodent models has characterized 25CN-NBOH across multiple behavioral and physiological endpoints. In mice, the compound produces a dose-dependent head-twitch response (the canonical 5-HT2A-mediated behavioral readout) with an inverted U-shaped dose-response curve peaking at 1.5 mg/kg and a half-maximal time of approximately 11 minutes, with both tachyphylaxis within sessions and tolerance across days consistent with 5-HT2A receptor desensitization. In rats, a single administration of 25CN-NBOH reduces immobility in the forced swim test with an effect size persisting without decrement for at least three months, paralleling the long-lasting antidepressant-like activity of psilocybin and supporting the hypothesis that 5-HT2A receptor activation underlies the enduring behavioral effects of serotonergic psychedelics. A single dose enhances cognitive flexibility in a reversal learning paradigm two to three weeks after administration. Additional preclinical findings include reduction of conditioned fear (blocked by the 5-HT2A inverse agonist MDL100907), reduction of marble burying behavior, cardiovascular effects including tachycardia and temperature-dependent modulation of carotid blood flow, and complex dual actions on medial prefrontal cortical neurons comprising 5-HT2A-dependent excitatory synaptic enhancement and 5-HT2A-independent M-current-mediated suppression of neuronal firing.

    Pharmacokinetic characterization in mice demonstrates rapid brain penetration (free brain and plasma concentrations of approximately 200 nanomolar within 15 minutes after 3 mg/kg subcutaneous administration), high in vitro permeability (apparent permeability coefficient 29 times 10 to the negative 6 centimeters per second), and low P-glycoprotein-mediated efflux. The compound is metabolized more slowly than the NBOMe congeners and displays favorable physicochemical properties including aqueous stability of the hydrochloride salt at room temperature for weeks.

    No human clinical trials of 25CN-NBOH have been conducted or registered as of the monograph date. The compound is not approved for any therapeutic indication in any jurisdiction and is classified as a controlled substance in the United Kingdom (Class A), Hungary, and Canada, and is potentially controlled in the United States under the Federal Analogue Act when intended for human consumption. This monograph reviews the chemistry, synthesis, receptor pharmacology, structural biology, pharmacokinetics, preclinical behavioral and physiological pharmacology, sourcing and handling considerations, and comparative assessment of 25CN-NBOH against five alternative 5-HT2A receptor agonists on five competency standards.

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  • Magnesium

    Essential divalent cation and enzymatic cofactor with voltage-dependent NMDA receptor antagonism and broad physiological regulatory activity

    An essential mineral element required as a cofactor in over 600 enzymatic reactions, distinguished by its voltage-dependent block of the NMDA receptor ion channel, its role in cellular energy metabolism through ATP chelation, and its broad clinical evidence base spanning cardiovascular, neurological, musculoskeletal, and metabolic indications.

    Abstract

    Magnesium (Mg2+) is the second most abundant intracellular cation, the fourth most abundant cation in the human body, and an essential cofactor in more than 600 enzymatic reactions encompassing DNA and RNA synthesis, protein synthesis, cellular energy metabolism, ion channel regulation, and neuromuscular function. Total body magnesium in the adult human is approximately 24 to 29 grams, of which approximately 60 percent resides in bone mineral, 39 percent in intracellular soft tissue compartments, and less than 1 percent in extracellular fluid and plasma. Serum magnesium concentration in healthy adults is maintained within a narrow physiological range of 0.75 to 0.95 millimoles per liter through coordinated intestinal absorption, renal reabsorption, and osseous exchange, with the transient receptor potential melastatin channels TRPM6 and TRPM7 serving as the principal apical magnesium entry pathways in intestinal and renal epithelial cells. The molecular pharmacology of magnesium is anchored by its voltage-dependent block of the N-methyl-D-aspartate (NMDA) receptor ion channel, a mechanism through which extracellular Mg2+ occupies a binding site within the channel pore at resting membrane potential and is expelled upon postsynaptic depolarization, thereby gating calcium influx and serving as a coincidence detector for synaptic plasticity. This NMDA receptor interaction, together with magnesium’s roles as a physiological calcium antagonist, a modulator of potassium and sodium channel conductance, and a required cofactor for ATP-dependent kinase and phosphatase reactions, underlies the broad clinical pharmacology of the element across neurological, cardiovascular, musculoskeletal, and metabolic systems. Subclinical magnesium deficiency is increasingly recognized as a prevalent and underdiagnosed condition, with epidemiological surveys indicating that approximately 50 to 80 percent of adults in industrialized nations consume less than the estimated average requirement. The clinical consequences of chronic marginal magnesium status include increased risk of hypertension, type 2 diabetes mellitus, metabolic syndrome, coronary artery disease, stroke, migraine, depression, and osteoporosis. The tolerable upper intake level for supplemental magnesium from nonfood sources is set at 350 milligrams per day for adults by the United States Institute of Medicine, though this threshold is under active re-evaluation in light of accumulating evidence that higher supplemental intakes are well tolerated in individuals with normal renal function. Magnesium is available in numerous supplemental salt forms that differ substantially in elemental magnesium content, solubility, bioavailability, and tissue distribution. Organic salts (citrate, glycinate, taurate, malate, threonate) demonstrate superior bioavailability compared to inorganic forms (oxide, hydroxide, carbonate, sulfate) in human pharmacokinetic studies. Magnesium L-threonate has attracted particular research interest for its capacity to elevate brain magnesium concentrations through blood-brain barrier penetration via glucose transporters, with randomized controlled trials demonstrating significant improvements in cognitive performance and working memory. This monograph documents the chemical identity, discovery history, molecular pharmacology, pharmacokinetics across supplemental forms, preclinical and clinical evidence base, sourcing and quality verification, reconstitution and handling, stack interactions, adverse event profile, and a comparative assessment of five magnesium salt forms against five competency standards. The compound is generally recognized as safe at recommended supplemental doses in individuals with normal renal function; dose adjustment or avoidance is indicated in moderate to severe renal impairment.

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  • Schisandrin B

    Dibenzocyclooctadiene lignan with pleiotropic antioxidant, hepatoprotective, anti-inflammatory, and cytoprotective activity

    A principal bioactive dibenzocyclooctadiene lignan isolated from the fruit of Schisandra chinensis, distinguished by potent Nrf2-dependent antioxidant induction, NF-kB suppression, mitochondrial protective activity, and hepatoprotective efficacy across multiple preclinical models of chemical, ischemic, and metabolic liver injury.

    Abstract

    Schisandrin B (Sch B), also designated gamma-schisandrin, is the most pharmacologically characterized dibenzocyclooctadiene lignan isolated from the dried ripe fruit of Schisandra chinensis (Turcz.) Baill., a climbing vine of the family Schisandraceae with a history of use in traditional Chinese medicine spanning more than two millennia under the name wuweizi (five-flavor berry). Among the more than 30 structurally related lignans present in the Schisandra fruit, Schisandrin B has attracted the greatest research attention owing to a convergence of potent antioxidant, anti-inflammatory, hepatoprotective, cardioprotective, and neuroprotective activities demonstrated across a substantial body of in vitro and in vivo preclinical literature. The compound acts principally through activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) transcription factor and its downstream antioxidant response element (ARE)-dependent gene program, producing upregulation of glutathione S-transferase, heme oxygenase-1, NAD(P)H:quinone oxidoreductase 1, superoxide dismutase, and catalase. Concurrently, Schisandrin B suppresses NF-kB nuclear translocation and downstream proinflammatory cytokine expression (tumor necrosis factor alpha, interleukin-1 beta, interleukin-6) through inhibition of IkB-alpha degradation and suppression of MAPK cascade phosphorylation at c-Raf, MEK, ERK, JNK, and p38 nodes. Additional characterized mechanisms include enhancement of mitochondrial glutathione antioxidant status and heat shock protein induction, activation of the SIRT1/PI3K/Akt and AMPK/mTOR signaling axes, suppression of ferroptosis through upregulation of SLC7A11, GPX4, and FTH1, and modulation of pregnane X receptor (PXR)-mediated bile acid metabolism. The hepatoprotective activity is the best-validated pharmacological property: Schisandrin B protects against carbon tetrachloride-induced hepatotoxicity, D-galactosamine-induced hepatocyte apoptosis, ischemia-reperfusion liver injury, doxorubicin and pirarubicin-induced hepatotoxicity, acetaminophen hepatotoxicity, cholestatic liver injury, and metabolic-associated fatty liver disease in rodent models, with efficacy demonstrated at oral doses typically in the range of 25 to 100 mg/kg in mice and rats. The compound also exhibits preclinical cardioprotective activity against doxorubicin cardiotoxicity and angiotensin II-induced cardiac fibrosis, and neuroprotective activity against amyloid-beta-induced neuronal dysfunction, scopolamine-induced amnesia, and cisplatin-induced neurotoxicity. Pharmacokinetic characterization in rats demonstrates oral bioavailability of approximately 19 to 55 percent (with sex-dependent variation), extensive hepatic accumulation consistent with its liver-protective profile, a double-peak absorption curve suggestive of enterohepatic circulation, and linear pharmacokinetics across the 10 to 40 mg/kg oral dose range. Schisandrin B is a potent, dose-dependent, noncompetitive inhibitor of CYP3A activity (Ki approximately 16.6 mg/kg in vivo) and inhibits P-glycoprotein-mediated efflux, producing clinically relevant herb-drug interactions with CYP3A substrates including midazolam, tacrolimus, and sirolimus. The compound has not been evaluated in human clinical trials as an isolated entity; all pharmacological and safety characterization derives from preclinical studies and from clinical experience with Schisandra chinensis fruit extracts and the semi-synthetic derivative bifendate (dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethylenedioxybiphenyl-2,2′-dicarboxylate). Preclinical toxicology in dogs has demonstrated dose-dependent plasma accumulation on repeated administration, and in vitro studies at high concentrations have identified paradoxical hepatotoxicity in mouse hepatocytes and macrophages, indicating that the therapeutic window requires careful characterization before clinical translation. This monograph documents the chemistry, stereochemistry, and botanical source of Schisandrin B; the molecular pharmacology across Nrf2, NF-kB, SIRT1, AMPK, and mitochondrial mechanisms; the preclinical pharmacokinetic profile; the comprehensive preclinical evidence base across hepatoprotective, cardioprotective, neuroprotective, anti-inflammatory, and antitumor indications; sourcing and quality verification; reconstitution and handling; stack interactions with emphasis on CYP3A and P-glycoprotein; adverse events and safety signals including dose-dependent hepatotoxicity; and a comparative assessment of five related hepatoprotective or Nrf2-activating compounds against Schisandrin B on five competency standards.

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  • UBX1325

    Senolytic Bcl-xL inhibitor (phosphate prodrug); small-molecule inducer of apoptosis in senescent retinal vascular endothelial cells

    A first-in-class senolytic Bcl-xL inhibitor developed by Unity Biotechnology as an intravitreal therapy for diabetic macular edema and age-related macular degeneration, distinguished from conventional anti-VEGF agents by its mechanism of selective elimination of senescent retinal vascular cells and its potential for durable, disease-modifying efficacy from infrequent dosing.

    Abstract

    UBX1325 (foselutoclax) is a soluble phosphate prodrug that is cleaved rapidly in ocular tissues by ubiquitous phosphatases to yield the active parent molecule UBX0601, a potent inhibitor of the B-cell lymphoma-extra large (Bcl-xL) anti-apoptotic protein and related Bcl-2 family members. The compound was developed by Unity Biotechnology as the first senolytic therapeutic candidate designed for intravitreal administration in ophthalmologic indications, principally diabetic macular edema (DME), diabetic retinopathy (DR), and neovascular (wet) age-related macular degeneration (AMD). The senolytic mechanism is fundamentally distinct from the anti-vascular endothelial growth factor (anti-VEGF) agents that constitute the current standard of care for these conditions: rather than neutralizing a single cytokine to reduce vascular permeability, UBX1325 selectively induces apoptosis in senescent retinal vascular endothelial cells that have accumulated in areas of disease activity, thereby removing a persistent source of pro-inflammatory and pro-permeability signaling and potentially modifying the underlying disease process rather than managing its downstream consequences.

    The compound originated from a 2016 strategic licensing arrangement between Unity Biotechnology and Ascentage Pharma, under which Unity screened Ascentage’s Bcl-2 family compound library for candidates with senolytic activity against age-related disease targets. The selected molecule, BM-962, was optimized as a phosphate prodrug (UBX1325/foselutoclax) to improve aqueous solubility for ophthalmic formulation. Preclinical studies demonstrated that intravitreal administration of UBX1325 in oxygen-induced retinopathy and streptozotocin-induced diabetic retinopathy mouse models selectively eliminated senescent cells from diseased retinal vasculature while sparing healthy tissue, reduced retinal vascular permeability, and improved retinal function as measured by electroretinography. A Phase 1 single ascending dose study in 12 patients with advanced DME and wet AMD (NCT04537884) established safety and tolerability at doses up to 10 micrograms, with no dose-limiting toxicities, no treatment-related serious adverse events, and encouraging signals of visual acuity improvement and retinal thickness reduction persisting through 12 weeks. The Phase 2 BEHOLD trial (NCT04857996) enrolled 65 patients with DME who had suboptimal response to prior anti-VEGF therapy and randomized them to a single intravitreal injection of 10 micrograms UBX1325 or sham; at 48 weeks, UBX1325-treated patients gained a mean of 6.2 ETDRS letters from baseline (5.6 letters over sham), with 53 percent of treated patients requiring no anti-VEGF rescue through the full study duration compared to 22 percent in the sham arm. These results, published in Nature Medicine in 2024, represent the first clinical demonstration of senolytic therapy in ophthalmology. The Phase 2 ENVISION trial (NCT05275205) in wet AMD did not meet its primary non-inferiority endpoint versus aflibercept at 24 weeks, though 40 percent of UBX1325-treated patients required no anti-VEGF rescue through 48 weeks. The Phase 2b ASPIRE trial (NCT06011798) evaluated repeat dosing of UBX1325 every 8 weeks versus aflibercept every 8 weeks in 52 DME patients; at 36 weeks, UBX1325 produced mean gains of 5.5 ETDRS letters, achieving non-inferiority to aflibercept at most time points except the pre-specified primary endpoint (average of weeks 20 and 24), with superior performance in a pre-specified subgroup of patients with baseline central subfield thickness below 400 microns.

    This monograph reviews the chemistry, prodrug design, and molecular pharmacology of UBX1325; the senolytic mechanism of action through Bcl-xL inhibition; the preclinical pharmacology in retinal disease models; the complete clinical evidence base across Phase 1, BEHOLD, ENVISION, and ASPIRE trials; reconstitution and handling considerations for intravitreal formulation; stack interactions with anti-VEGF agents and corticosteroids; the adverse-event and safety profile; and a structured comparative assessment of five alternative approaches to DME therapy (aflibercept, faricimab, ranibizumab, navitoclax, and dasatinib plus quercetin) against UBX1325 on five competency standards. The compound is not approved by any regulatory authority as of the monograph revision date. Unity Biotechnology is advancing development toward registrational trials.

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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.