Category: Uncategorized

  • Etifoxine

    Non-benzodiazepine benzoxazine anxiolytic with dual GABAA receptor positive allosteric modulation and TSPO-mediated neurosteroidogenesis

    A non-benzodiazepine benzoxazine derivative developed by Hoechst AG and marketed as Stresam, distinguished from classical benzodiazepine anxiolytics by a dual mechanism encompassing direct positive allosteric modulation of beta2/beta3-containing GABAA receptors and stimulation of endogenous neurosteroid biosynthesis through the 18 kDa translocator protein (TSPO), conferring anxiolytic, anticonvulsant, and neuroprotective activity without the sedation, amnesia, tolerance, and dependence liabilities of the benzodiazepine class.

    Abstract

    Etifoxine (6-chloro-N-ethyl-4-methyl-4-phenyl-4H-3,1-benzoxazin-2-amine) is a non-benzodiazepine anxiolytic of the benzoxazine structural class, first synthesized by Hoechst AG in 1966 and introduced for clinical use in France in 1979 under the trade name Stresam. The compound is marketed in approximately 40 countries for the treatment of anxiety disorders, principally adjustment disorders with anxiety, but has not been approved by the United States Food and Drug Administration or by the European Medicines Agency for centralized marketing authorization across the European Union. Etifoxine is pharmacologically distinguished from both the benzodiazepine class and from other non-benzodiazepine anxiolytics (buspirone, hydroxyzine) by a dual mechanism of action at the GABAergic system. The first mechanism is direct positive allosteric modulation of the GABAA receptor through binding at the beta subunit, with preferential potentiation of receptors containing beta2 or beta3 subunits, at a site distinct from the benzodiazepine binding site located at the alpha/gamma interface. The second mechanism is binding to the 18 kDa translocator protein (TSPO, formerly the peripheral benzodiazepine receptor) on the outer mitochondrial membrane, which stimulates the translocation of cholesterol into the mitochondrial matrix and the subsequent biosynthesis of endogenous neurosteroids, principally pregnenolone, progesterone, 5-alpha-dihydroprogesterone, and allopregnanolone. Allopregnanolone is itself a potent positive allosteric modulator of the GABAA receptor at the neurosteroid binding site (distinct from both the benzodiazepine and the etifoxine direct binding sites), producing a convergent, temporally extended potentiation of GABAergic inhibitory neurotransmission. This dual mechanism produces anxiolytic efficacy comparable to benzodiazepines in clinical trials of adjustment disorder with anxiety, with significantly reduced incidence of sedation, psychomotor impairment, amnesia, rebound anxiety on withdrawal, and physical dependence. Pharmacokinetics are characterized by rapid oral absorption, high bioavailability (approximately 90 percent), hepatic metabolism to an active metabolite (diethyl-etifoxine) with a half-life of approximately 20 hours, and predominant renal excretion. The clinical evidence base includes multiple randomized controlled trials comparing etifoxine to lorazepam, alprazolam, and placebo in adjustment disorder with anxiety, with the AMETIS study (a three-arm trial versus lorazepam and placebo) producing a notable negative result in which neither active arm separated from placebo. The compound has an established clinical safety profile over more than 40 years of marketed use, with rare but serious adverse events including severe cutaneous reactions (drug reaction with eosinophilia and systemic symptoms, Stevens-Johnson syndrome, erythema multiforme) and hepatotoxicity (acute cytolytic hepatitis), which prompted a 2021 European Medicines Agency Article 31 referral concluded in January 2022 with continued marketing authorization subject to contraindication in patients with prior severe dermatological or hepatic reactions. Beyond the anxiolytic indication, etifoxine has generated a substantial preclinical research literature in neuroprotection following peripheral nerve injury, traumatic brain injury, experimental autoimmune encephalomyelitis (a model of multiple sclerosis), and neuropathic pain, with the neuroprotective activity attributed to TSPO-mediated neurosteroidogenesis and downstream anti-inflammatory and neurotrophic effects. A deuterated analog, GRX-917 (GABA Therapeutics, a subsidiary of atai Life Sciences), has completed Phase 1 clinical trials with improved pharmacokinetic properties and is in development for anxiety and related disorders. This monograph reviews the chemistry, synthesis, and structural classification of etifoxine; the dual-receptor mechanism in molecular and electrophysiological detail; the comprehensive pharmacokinetic record; the preclinical pharmacology across neuroprotection, nerve injury, traumatic brain injury, and pain models; the clinical evidence base in anxiety disorders; sourcing and quality verification; reconstitution and handling; stack-interaction considerations; adverse-event signal including the EMA referral outcome; and a comparative assessment of five anxiolytic alternatives against etifoxine on five competency standards.

    Read the full monograph

    The full reference document covers compound identification, discovery and developmental history, mechanism of action, pharmacokinetics, sourcing and quality verification, and a curated reference list. Embedded inline below; download for offline reading.

    KDC-MN-1585Open in new tab →

    Download PDF →

    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.

  • Hydroxynorketamine

    Cyclohexanone-based ketamine metabolite with AMPA receptor-potentiating and rapid antidepressant activity

    A hydroxylated norketamine metabolite identified as a principal mediator of ketamine’s rapid antidepressant effects, distinguished from the parent compound by the absence of NMDA receptor blockade at therapeutic concentrations, lack of dissociative and abuse-related properties, and a novel mechanism converging on AMPA receptor potentiation, BDNF-TrkB signaling, and mGlu2 receptor-dependent glutamatergic plasticity.

    Abstract

    Hydroxynorketamine (HNK) refers to a family of twelve stereoisomeric metabolites of the dissociative anesthetic and rapid-acting antidepressant ketamine, formed by cytochrome P450-mediated hydroxylation of the intermediate metabolite norketamine at the 4-, 5-, or 6-position of the cyclohexane ring. The (2R,6R)-hydroxynorketamine stereoisomer ((2R,6R)-HNK) has emerged as the compound of greatest pharmacological interest following the seminal 2016 report by Zanos et al. in Nature demonstrating that this metabolite is both necessary and sufficient for the antidepressant actions of ketamine in rodent models, while lacking the anesthetic, dissociative, psychotomimetic, and abuse-related properties of the parent compound. The molecular pharmacology of (2R,6R)-HNK is distinct from ketamine: at concentrations relevant to antidepressant activity, (2R,6R)-HNK does not produce meaningful inhibition of N-methyl-D-aspartate (NMDA) receptors, but instead potentiates alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor-mediated glutamatergic transmission through a presynaptic mechanism that increases glutamate release probability and enhances synaptic plasticity in hippocampal and prefrontal cortical circuits. Downstream consequences include activity-dependent release of brain-derived neurotrophic factor (BDNF), activation of tropomyosin receptor kinase B (TrkB) signaling, stimulation of the mechanistic target of rapamycin complex 1 (mTORC1) pathway, and rapid synaptogenesis in the medial prefrontal cortex. Additional mechanistic contributions involve metabotropic glutamate receptor subtype 2 (mGlu2) receptor-dependent signaling and antagonism of alpha-7 nicotinic acetylcholine receptors controlling presynaptic function and neuroplasticity gene expression. Pharmacokinetically, (2R,6R)-HNK is formed in vivo from (R)-ketamine through sequential N-demethylation (predominantly CYP2B6 and CYP3A4) to (R)-norketamine and subsequent 6-hydroxylation (predominantly CYP2B6 and CYP2A6). The metabolite is brain-penetrant following peripheral administration, with rapid onset of central nervous system exposure. A Phase 1 clinical trial (NCT04711005) published by Raja et al. in 2024 demonstrated excellent safety and tolerability of intravenous (2R,6R)-HNK at doses from 0.1 to 4 mg/kg in healthy volunteers, with no dissociative effects, no serious adverse events, and a pharmacokinetic profile consistent with once-daily or intermittent dosing. Phase 2 trials in treatment-resistant depression (NCT06511908) and Phase 1/2 trials in neuropathic pain (NCT05864053) and obsessive-compulsive disorder (NCT06575075) are currently enrolling. Preclinical evidence across multiple rodent models demonstrates antidepressant-like, anxiolytic, analgesic, and anti-inflammatory effects, with effect sizes comparable to or exceeding those of the parent ketamine in several paradigms and duration of action extending well beyond the plasma residence time, consistent with a synaptic plasticity-dependent rather than receptor occupancy-dependent mechanism. This monograph reviews the chemistry, stereochemistry, and metabolic origin of hydroxynorketamine; the molecular pharmacology at AMPA, NMDA, mGlu2, alpha-7 nicotinic, and opioid receptors; the comprehensive pharmacokinetic record; the preclinical evidence base across depression, pain, anxiety, and substance use disorder models; the emerging clinical evidence from Phase 1 and ongoing Phase 2 trials; sourcing and quality verification; reconstitution and handling; stack interactions and combinations; adverse events and safety signal; and a comparative assessment of five rapid-acting antidepressant candidates against hydroxynorketamine on five competency standards.

    Read the full monograph

    The full reference document covers compound identification, discovery and developmental history, mechanism of action, pharmacokinetics, sourcing and quality verification, and a curated reference list. Embedded inline below; download for offline reading.

    KDC-MN-1588Open in new tab →

    Download PDF →

    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.

  • Nebivolol

    Third-generation beta-1 selective adrenergic receptor antagonist with nitric oxide-mediated vasodilatory activity

    A highly beta-1 selective adrenergic receptor antagonist distinguished from all other marketed beta-blockers by endothelial nitric oxide-dependent vasodilation mediated through beta-3 adrenergic receptor agonism and GRK/beta-arrestin biased signaling, conferring hemodynamic, metabolic, and tolerability advantages in hypertension and heart failure.

    Abstract

    Nebivolol is a third-generation beta-adrenergic receptor antagonist with the highest beta-1 selectivity among clinically available beta-blockers and a unique vasodilatory mechanism mediated by endothelial nitric oxide (NO) release. The compound was patented by Janssen Pharmaceutica in 1983, entered clinical use in Europe in 1997, and received United States Food and Drug Administration approval in December 2007 for the treatment of hypertension, marketed as Bystolic by Forest Laboratories (now Allergan/AbbVie). Nebivolol is a racemic mixture of equal proportions of d-nebivolol (SRRR configuration) and l-nebivolol (RSSS configuration), each containing four stereocenters within a bis-chromanol scaffold linked by an aminoethanol bridge. The d-enantiomer carries the beta-1 adrenergic antagonist activity, while the l-enantiomer predominantly mediates nitric oxide release through beta-3 adrenergic receptor agonism and activation of endothelial nitric oxide synthase (eNOS) via serine-1177 phosphorylation. This dual mechanism produces a hemodynamic profile that combines heart rate reduction and negative inotropy (classical beta-blockade) with peripheral vasodilation and reduced systemic vascular resistance (NO-mediated), distinguishing nebivolol from older beta-blockers that increase or fail to reduce peripheral resistance.

    The pharmacokinetic profile is dominated by extensive hepatic metabolism through cytochrome P450 2D6 (CYP2D6), producing a striking polymorphic phenotype: oral bioavailability is approximately 12 percent in extensive metabolizers and rises to approximately 96 percent in poor metabolizers. The plasma elimination half-life of d-nebivolol is approximately 12 hours in extensive metabolizers and approximately 19 hours in poor metabolizers. Steady-state plasma concentrations in poor metabolizers are 10- to 15-fold higher than in extensive metabolizers at equivalent doses. The CYP2D6 dependence has direct clinical implications for dose adjustment, drug-drug interactions with CYP2D6 inhibitors (fluoxetine, paroxetine, quinidine), and inter-individual variability in blood pressure response.

    The principal clinical evidence base comprises the SENIORS trial (Study of Effects of Nebivolol Intervention on Outcomes and Rehospitalisation in Seniors with Heart Failure), which randomized 2128 elderly patients (age 70 years or older) with symptomatic heart failure to nebivolol or placebo and demonstrated a significant reduction in the composite primary endpoint of all-cause mortality or cardiovascular hospital admission (hazard ratio 0.86, 95 percent confidence interval 0.74 to 0.99, P = 0.039). Multiple randomized controlled trials in hypertension have demonstrated blood pressure reductions comparable to or exceeding those of other beta-blockers, with superior tolerability including significantly lower rates of fatigue, sexual dysfunction, and metabolic derangement (glucose and lipid abnormalities). Preclinical evidence demonstrates cardioprotective, antioxidant, and anti-inflammatory properties mediated through beta-3 receptor stimulation, NLRP3 inflammasome suppression, and mitochondrial biogenesis enhancement.

    This monograph reviews the chemistry, stereochemistry, and synthesis of nebivolol; the dual beta-1 antagonist and NO-mediated vasodilatory mechanism in molecular detail; the comprehensive human pharmacokinetic record including CYP2D6 polymorphism; preclinical pharmacology across cardiovascular, metabolic, and inflammatory models; the clinical evidence base in hypertension and heart failure; sourcing and quality verification; reconstitution and handling; stack-interaction considerations; adverse-event profile; and a comparative assessment of five alternative beta-blockers (metoprolol, bisoprolol, carvedilol, atenolol, propranolol) against nebivolol on five competency standards (novelty, effect size, tolerability profile, metabolic neutrality, and overall validation).

    Read the full monograph

    The full reference document covers compound identification, discovery and developmental history, mechanism of action, pharmacokinetics, sourcing and quality verification, and a curated reference list. Embedded inline below; download for offline reading.

    KDC-MN-1558Open in new tab →

    Download PDF →

    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.

  • Salidroside

    Phenylpropanoid glycoside (tyrosol 8-O-beta-D-glucopyranoside) adaptogen with pleiotropic antioxidant, anti-inflammatory, and neuroprotective activity

    A naturally occurring phenylethanol glycoside isolated from Rhodiola rosea and related Crassulaceae species, characterized by activation of the AMPK/Nrf2 axis and inhibition of NF-kappaB-driven inflammation, with a broad preclinical evidence base spanning neuroprotection, cardioprotection, metabolic regulation, and anti-tumor activity, and emerging clinical evidence in stress adaptation and exercise performance.

    Abstract

    Salidroside (2-(4-hydroxyphenyl)ethyl beta-D-glucopyranoside; CAS 10338-51-9) is the principal bioactive glycoside of the adaptogenic plant Rhodiola rosea L. and related Rhodiola species of the family Crassulaceae. It is the 8-O-beta-D-glucoside of tyrosol (4-hydroxyphenylethanol), a simple phenylethanol aglycone that is also the primary circulating metabolite of salidroside following oral administration. The compound has been used in traditional Tibetan, Chinese, and Scandinavian medicine for centuries as a general tonic and adaptogen, and modern pharmacological investigation has identified a remarkably diverse spectrum of biological activities centered on three principal molecular mechanisms: activation of the AMP-activated protein kinase (AMPK) signaling cascade with downstream engagement of the PI3K/Akt/GSK3beta and SIRT1 pathways; activation of the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) antioxidant response axis; and suppression of the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kappaB) pro-inflammatory transcriptional program with consequent reduction of tumor necrosis factor alpha, interleukin-1 beta, interleukin-6, and NLRP3 inflammasome activation.

    Preclinical pharmacology studies conducted across multiple organ systems have demonstrated neuroprotective efficacy in models of cerebral ischemia/reperfusion injury, Alzheimer’s disease (amyloid beta-induced neurotoxicity and ferroptosis), Parkinson’s disease (MPTP and 6-OHDA models), traumatic brain injury, and depression; cardioprotective activity against ischemia/reperfusion injury, doxorubicin-induced cardiotoxicity, and atherosclerosis; hepatoprotective effects against carbon tetrachloride and high-fat-diet-induced liver injury and nonalcoholic steatohepatitis; antidiabetic activity through amelioration of insulin resistance via the mitochondria-associated AMPK/PI3K/Akt/GSK3beta pathway; renoprotective effects in diabetic nephropathy; and anti-tumor activity in breast, lung, colorectal, and gastric cancer models through inhibition of proliferation, migration, and invasion via the AKT and MEK/ERK signaling pathways.

    Pharmacokinetics in rodents are characterized by rapid oral absorption (Tmax approximately 0.5 to 1 hour), moderate oral bioavailability (approximately 20 to 32 percent in rats), extensive first-pass metabolism to the aglycone p-tyrosol by intestinal and hepatic beta-glucosidases, wide tissue distribution with preferential accumulation in kidney, liver, and heart, and renal elimination of conjugated metabolites. The compound crosses the blood-brain barrier. Salidroside demonstrates a favorable safety profile: the acute oral LD50 in rats exceeds 5000 mg/kg body weight, and subchronic toxicity studies at doses up to 100 mg/kg/day have not produced organ toxicity, genotoxicity, or teratogenicity at the studied doses.

    Human clinical evidence remains limited relative to the preclinical literature. Rhodiola rosea standardized extracts containing salidroside (typically standardized to 1 to 3 percent salidroside) have demonstrated efficacy in randomized controlled trials for stress-related fatigue, mild to moderate depression, generalized anxiety, and cognitive function under stress conditions. A 2024 exploratory randomized double-blind placebo-controlled trial of pure biosynthetic salidroside at 60 mg/day for 16 days in healthy active young adults demonstrated enhanced oxygen utilization during high-intensity intermittent exercise, stable mood states, and mitigated exercise-induced muscle damage. A randomized controlled trial of 60 breast cancer patients reported no clinical adverse events during salidroside administration as adjunctive therapy.

    This monograph reviews the chemistry, natural and synthetic sources, and structural pharmacology of salidroside; the multi-target molecular mechanisms across the AMPK, Nrf2, and NF-kappaB axes; the comprehensive preclinical pharmacology across neurological, cardiovascular, metabolic, hepatic, renal, and oncological models; the available human pharmacokinetic and clinical evidence; sourcing, quality verification, and standardization considerations; reconstitution and handling protocols; stack-interaction implications; adverse-event and safety signal characterization; and a structured comparative assessment of five adaptogenic or neuroprotective compounds against salidroside on five competency standards.

    Read the full monograph

    The full reference document covers compound identification, discovery and developmental history, mechanism of action, pharmacokinetics, sourcing and quality verification, and a curated reference list. Embedded inline below; download for offline reading.

    KDC-MN-1613Open in new tab →

    Download PDF →

    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.

  • Suzetrigine

    Selective NaV1.8 voltage-gated sodium channel inhibitor (non-opioid peripheral analgesic)

    A first-in-class, peripherally restricted NaV1.8 sodium channel inhibitor developed by Vertex Pharmaceuticals as a non-opioid analgesic for moderate-to-severe acute pain, distinguished by allosteric binding to voltage-sensing domain 2 and greater than 31,000-fold selectivity over all other sodium channel subtypes.

    Abstract

    Suzetrigine (VX-548; trade name Journavx) is the first selective inhibitor of the NaV1.8 voltage-gated sodium channel to receive regulatory approval, granted by the United States Food and Drug Administration on 30 January 2025 for the treatment of moderate-to-severe acute pain in adults. The compound represents a mechanistically novel analgesic class, acting by allosteric binding to the extracellular S3-S4 loop of voltage-sensing domain 2 (VSD2) of the NaV1.8 channel, where a KKGS amino acid sequence unique to this subtype confers greater than 31,000-fold selectivity over the other nine human voltage-gated sodium channel isoforms. NaV1.8, encoded by the SCN10A gene, is expressed almost exclusively in peripheral nociceptive neurons of the dorsal root ganglia, where it contributes more than 70 percent of the depolarizing current during pain-signaling action potentials. Suzetrigine stabilizes the channel in its closed (resting) state through tonic inhibition that is independent of channel opening frequency, thereby reducing pathological nociceptor hyperexcitability without affecting cardiac, central nervous system, or skeletal muscle sodium channels.

    The compound emerged from a multi-year medicinal chemistry program at Vertex Pharmaceuticals that progressed through the predecessors VX-128 and VX-150 before arriving at VX-548, which demonstrated an in vitro IC50 of 0.68 nanomolar against human NaV1.8 with negligible activity (IC50 greater than 10,000 nanomolar) against all other NaV subtypes. In Phase 2 randomized controlled trials in postoperative bunionectomy and abdominoplasty pain, suzetrigine at a 100 mg loading dose followed by 50 mg every 12 hours produced statistically significant reductions in the time-weighted sum of pain intensity difference over 48 hours (SPID48) compared to placebo (37.8-point and 36.8-point superiority, respectively). In the pivotal Phase 3 NAVIGATE-1 (bunionectomy, N = 1,073) and NAVIGATE-2 (abdominoplasty, N = 1,118) trials, suzetrigine achieved statistically significant superiority over placebo on SPID48 (p = 0.0002 and p < 0.0001, respectively), with analgesic efficacy broadly comparable to hydrocodone/acetaminophen but without opioid-class adverse effects including respiratory depression, sedation, or abuse liability.

    Pharmacokinetics are characterized by oral administration with a time to peak plasma concentration of approximately 3 hours in the fasted state, extensive tissue distribution (volume of distribution approximately 495 liters), 99 percent plasma protein binding, and hepatic metabolism predominantly through CYP3A enzymes to the active metabolite M6-SUZ (3.7-fold less potent than parent compound). The terminal elimination half-life of suzetrigine is 23.6 hours, and that of M6-SUZ is 33.0 hours, supporting twice-daily maintenance dosing. Excretion occurs through both fecal (49.9 percent) and urinary (44.0 percent) routes. The compound is contraindicated with strong CYP3A4 inhibitors and in severe hepatic impairment (Child-Pugh Class C). The most common adverse events in clinical trials were nausea, headache, dizziness, constipation, pruritus, muscle spasms, and rash, all predominantly mild to moderate in severity. No respiratory depression, physical dependence, or abuse potential has been identified in clinical or preclinical assessments.

    This monograph documents the chemistry, structural pharmacology, mechanism of action, comprehensive pharmacokinetics, preclinical and clinical evidence base, regulatory history, sourcing and handling considerations, drug interaction profile, adverse-event signal, and a structured comparative assessment of five alternative analgesic approaches (VX-150, hydrocodone/acetaminophen, pregabalin, celecoxib, and lidocaine 5% patch) against suzetrigine on five competency standards.

    Read the full monograph

    The full reference document covers compound identification, discovery and developmental history, mechanism of action, pharmacokinetics, sourcing and quality verification, and a curated reference list. Embedded inline below; download for offline reading.

    KDC-MN-1576Open in new tab →

    Download PDF →

    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.

  • TUDCA

    Hydrophilic taurine-conjugated bile acid with chemical chaperone activity and endoplasmic reticulum stress modulation

    A taurine conjugate of ursodeoxycholic acid distinguished by chemical chaperone activity at the endoplasmic reticulum, cytoprotective modulation of the unfolded protein response, and broad preclinical neuroprotective and metabolic activity across neurodegenerative, hepatobiliary, retinal, and metabolic disease models.

    Abstract

    Tauroursodeoxycholic acid (TUDCA) is a naturally occurring hydrophilic bile acid formed by taurine conjugation of ursodeoxycholic acid (UDCA), identified in bear bile in 1902 and used in traditional Chinese medicine for centuries prior to its modern pharmacological characterization. The compound functions principally as a chemical chaperone that alleviates endoplasmic reticulum (ER) stress by stabilizing the unfolded protein response (UPR) through modulation of the three canonical ER stress sensor pathways: PERK/eIF2alpha/ATF4, IRE1alpha/XBP1, and ATF6. Beyond ER stress modulation, TUDCA exerts potent anti-apoptotic activity through prevention of Bax translocation to mitochondrial membranes, inhibition of cytochrome c release, and activation of the PI3K/Akt survival pathway. The compound stabilizes mitochondrial membrane potential, reduces reactive oxygen species production, suppresses NF-kappaB-mediated proinflammatory cytokine release, and activates the nuclear receptor FXR and the membrane receptor TGR5. TUDCA crosses the blood-brain barrier and has demonstrated neuroprotective activity in preclinical models of Alzheimer’s disease (APP/PS1 transgenic mice, reducing amyloid-beta deposition and rescuing spatial memory), Parkinson’s disease (MPTP model, preventing dopaminergic neuronal loss), Huntington’s disease (3-nitropropionic acid model, preserving striatal mitochondria), amyotrophic lateral sclerosis (SOD1 transgenic mice), retinal degeneration (multiple retinitis pigmentosa models), and ischemic stroke (reducing infarct volume by approximately 50 percent). The clinical evidence base includes Phase II trials in amyotrophic lateral sclerosis demonstrating a favorable responder rate (87 percent versus 43 percent on placebo at 1 gram twice daily for 54 weeks in the Elia 2016 trial), a randomized controlled trial in obese insulin-resistant adults demonstrating a 30 percent improvement in hepatic and muscle insulin sensitivity at 1750 mg daily for 4 weeks, multiple trials in cholestatic liver disease demonstrating 40 to 51 percent reductions in liver enzymes, a Phase I/II trial in progressive multiple sclerosis demonstrating safety and immunological biomarker effects, and the Phase II CENTAUR trial of the combination product AMX0035 (TUDCA plus sodium phenylbutyrate) in ALS, which received accelerated FDA approval in September 2022 but was withdrawn from the market in October 2024 following the failure of the confirmatory Phase III PHOENIX trial to meet primary or secondary endpoints. A separate European Phase III trial (TUDCA-ALS) of TUDCA monotherapy in 337 ALS patients similarly failed to demonstrate efficacy at 18 months. The compound has been licensed for the treatment of cholestatic liver disease and cholesterol gallstones in several European and Asian jurisdictions since 1991 and maintains a favorable safety profile, with the principal adverse events being mild gastrointestinal effects (diarrhea in approximately 14 percent, abdominal pain in approximately 6 percent). This monograph reviews the chemistry, endogenous biosynthesis, and structural pharmacology of TUDCA; the multi-target cytoprotective mechanism spanning ER stress, mitochondrial stabilization, anti-apoptosis, and anti-inflammatory pathways; the comprehensive pharmacokinetic record including hepatic first-pass metabolism and blood-brain barrier penetration; the clinical evidence base across hepatobiliary, neurodegenerative, metabolic, retinal, and inflammatory indications; the reconstitution, sourcing, and stack-interaction considerations for laboratory and research applications; and a comparative assessment of five cytoprotective and neuroprotective candidates against TUDCA on five competency standards.

    Read the full monograph

    The full reference document covers compound identification, discovery and developmental history, mechanism of action, pharmacokinetics, sourcing and quality verification, and a curated reference list. Embedded inline below; download for offline reading.

    KDC-MN-1608Open in new tab →

    Download PDF →

    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.

  • Ezetimibe

    Selective cholesterol absorption inhibitor targeting Niemann-Pick C1-Like 1 (NPC1L1) transporter protein

    A 2-azetidinone cholesterol absorption inhibitor developed at the Schering-Plough Research Institute, first-in-class for selective blockade of Niemann-Pick C1-Like 1 mediated intestinal sterol uptake, with landmark cardiovascular outcomes evidence from the IMPROVE-IT trial and broad clinical positioning as add-on therapy to statins.

    Abstract

    Ezetimibe is a selective cholesterol absorption inhibitor and the founding member of a pharmacological class that targets the Niemann-Pick C1-Like 1 (NPC1L1) transporter protein at the brush border membrane of small intestinal enterocytes and on the canalicular membrane of hepatocytes. Developed at the Schering-Plough Research Institute through a medicinal chemistry program that originated in acyl-coenzyme A:cholesterol acyltransferase (ACAT) inhibitor optimization, the compound was identified as SCH 58235 and advanced to regulatory approval by the United States Food and Drug Administration in October 2002 for the treatment of primary hypercholesterolemia, homozygous familial hypercholesterolemia, homozygous sitosterolemia, and mixed hyperlipidemia. At the standard oral dose of 10 mg once daily, ezetimibe reduces intestinal cholesterol absorption by approximately 54 percent, produces a 15 to 22 percent reduction in low-density lipoprotein cholesterol (LDL-C) as monotherapy, and provides an incremental 23 to 24 percent LDL-C reduction when added to ongoing statin therapy. The molecular mechanism involves direct binding to NPC1L1, a polytopic transmembrane protein with sterol-sensing domains homologous to the Niemann-Pick type C1 protein (NPC1), blocking the clathrin/AP2-mediated endocytosis of the NPC1L1-cholesterol complex and thereby preventing cholesterol translocation from the intestinal lumen into the enterocyte cytoplasm.

    The pharmacokinetic profile is dominated by rapid absorption followed by extensive first-pass glucuronidation to the pharmacologically active ezetimibe-glucuronide conjugate, which constitutes 80 to 90 percent of circulating drug. Both ezetimibe and its glucuronide undergo enterohepatic recirculation, producing a prolonged effective half-life of approximately 22 hours that supports once-daily dosing. Metabolism is mediated principally by uridine 5′-diphosphate-glucuronosyltransferase (UGT) isoenzymes 1A1, 1A3, and 2B15, with minimal cytochrome P450 involvement, conferring a favorable drug-drug interaction profile relative to the statin class. Approximately 78 percent of the administered dose is excreted in feces, predominantly as parent ezetimibe, with the remainder recovered in urine as the glucuronide conjugate.

    The clinical evidence base for ezetimibe is anchored by two landmark cardiovascular outcomes trials. The IMPROVE-IT trial (Improved Reduction of Outcomes: Vytorin Efficacy International Trial), published in 2015, randomized 18,144 patients with recent acute coronary syndrome to simvastatin plus ezetimibe versus simvastatin plus placebo and demonstrated a statistically significant 6.4 percent relative reduction in the primary composite cardiovascular endpoint (hazard ratio 0.936, p = 0.016) at a median follow-up of six years, establishing ezetimibe as the first non-statin lipid-lowering agent to demonstrate incremental cardiovascular benefit when added to statin therapy [1]. The SHARP trial (Study of Heart and Renal Protection) randomized approximately 9,270 patients with chronic kidney disease to simvastatin plus ezetimibe versus placebo and demonstrated significant reduction in major atherosclerotic events [2]. These trials collectively validated the LDL-C hypothesis beyond the statin class and positioned ezetimibe as a standard component of guideline-directed lipid management.

    This monograph reviews the chemistry, synthesis, and structural pharmacology of ezetimibe; the NPC1L1 transporter biology and molecular mechanism of action; the comprehensive human pharmacokinetic record; the preclinical efficacy data in atherosclerosis and hypercholesterolemia models; the clinical evidence base across cardiovascular outcomes, chronic kidney disease, and combination therapy; sourcing and quality verification considerations; reconstitution and handling; stack interactions with statins, fibrates, bile acid sequestrants, and PCSK9 inhibitors; adverse events and safety signal including hepatic and musculoskeletal considerations; and a comparative assessment of five alternative non-statin lipid-lowering agents (bempedoic acid, evolocumab, alirocumab, inclisiran, colesevelam) against ezetimibe on five competency standards.

    Read the full monograph

    The full reference document covers compound identification, discovery and developmental history, mechanism of action, pharmacokinetics, sourcing and quality verification, and a curated reference list. Embedded inline below; download for offline reading.

    KDC-MN-1559Open in new tab →

    Download PDF →

    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.

  • Ibogainalog

    Non-selective serotonin receptor modulator, psychoplastogen, and ibogaine-derived tricyclic azepinoindole analog

    A simplified tricyclic ibogaine analog and potent 5-HT2A receptor agonist with psychoplastogenic, antidepressant, and analgesic activity, distinguished from the parent iboga alkaloids by dramatically reduced cardiotoxicity, absence of opioid receptor engagement, and retained promotion of structural neural plasticity.

    Abstract

    Ibogainalog (IBG; 9-methoxy-3-methyl-2,4,5,6-tetrahydro-1H-azepino[4,5-b]indole; CAS 802581-10-8) is a synthetic tricyclic azepinoindole and a structurally simplified analog of the iboga alkaloid ibogaine, first described in the chemical literature by Hester and colleagues in the late 1960s and subsequently characterized in pharmacological detail by the Olson laboratory at the University of California, Davis, beginning in 2020. The compound belongs to the ibogalog structural class, a family of substituted hexahydroazepino[4,5-b]indoles that retain the fused indole-azepine core of the iboga alkaloids while eliminating the isoquinuclidine ring system, yielding a dramatically simplified molecular architecture that is amenable to practical gram-scale synthesis. Ibogainalog is a non-selective serotonin receptor modulator with potent agonist activity at the 5-HT2A receptor (Ki approximately 670 nM; functional EC50 18 to 85 nM, 55 to 93 percent efficacy), the 5-HT6 receptor (EC50 7.1 to 8.8 nM, 83 to 99 percent efficacy), the 5-HT1F receptor (EC50 35 nM, 85 percent efficacy), and the 5-HT1B receptor (EC50 170 nM, 76 percent efficacy), with additional inverse agonist activity at the 5-HT7 receptor (EC50 335 nM) and mixed agonist-antagonist activity at the 5-HT2B and 5-HT2C receptors. The compound is a moderate serotonin reuptake inhibitor (SERT IC50 approximately 400 nM) with selectivity over the norepinephrine and dopamine transporters, and a noncompetitive inhibitor of the alpha-7 nicotinic acetylcholine receptor (IC50 approximately 11.4 micromolar) and a competitive inhibitor of the alpha-9-alpha-10 nicotinic acetylcholine receptor (IC50 approximately 2.9 micromolar). Critically, ibogainalog exhibits dramatically reduced potency at the hERG potassium channel relative to ibogaine (approximately 10-fold reduction), conferring a substantially improved cardiac safety profile; this is a principal design objective of the ibogalog class, given that ibogaine-associated QT prolongation and fatal cardiac arrhythmias have been a central safety concern limiting the clinical translation of ibogaine itself. The compound shows no agonist activity at opioid receptors, distinguishing it from the active ibogaine metabolite noribogaine. In preclinical behavioral models, ibogainalog at 10 mg/kg produces sustained antidepressant-like activity (persisting 72 hours in naive mice and 48 hours in chronically stressed mice) through a volinanserin-sensitive, 5-HT2A receptor-dependent serotonergic mechanism. The compound also produces dose-dependent antinociceptive activity in chronic constriction injury models of neuropathic pain and in dextran sulfate sodium-induced colitis models of visceral pain, with the longest anti-hyperalgesic duration among tested ibogalogs at comparatively lower doses. Analgesic activity is abolished by the 5-HT2A receptor antagonist ketanserin and involves synergistic crosstalk between 5-HT2A and metabotropic glutamate type 2 (mGlu2) receptors. As a psychoplastogen, ibogainalog promotes dendritic arborization and spinogenesis in cortical neurons at levels comparable to ibogaine, an activity mediated through 5-HT2A receptor signaling. Unlike the closely related ibogalog tabernanthalog, ibogainalog produces a measurable head-twitch response in rodent models, suggesting that it may retain psychedelic activity in humans, though the response magnitude is substantially reduced relative to classical psychedelics such as 5-methoxy-N,N-dimethyltryptamine. The compound is not in clinical development as of the date of this monograph; all evidence is preclinical. This monograph reviews the chemistry, synthesis, and structural class of ibogainalog; its multi-receptor serotonergic and nicotinic pharmacology; the available pharmacokinetic inference from the ibogalog class; the preclinical evidence base across antidepressant, analgesic, anti-addictive, and psychoplastogenic endpoints; sourcing and quality verification; reconstitution and handling; stack-interaction considerations; adverse-event signal from preclinical safety pharmacology; and a comparative assessment of five structurally or mechanistically related compounds against ibogainalog on five competency standards.

    Read the full monograph

    The full reference document covers compound identification, discovery and developmental history, mechanism of action, pharmacokinetics, sourcing and quality verification, and a curated reference list. Embedded inline below; download for offline reading.

    KDC-MN-1593Open in new tab →

    Download PDF →

    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.

  • 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).

    Read the full monograph

    The full reference document covers compound identification, discovery and developmental history, mechanism of action, pharmacokinetics, sourcing and quality verification, and a curated reference list. Embedded inline below; download for offline reading.

    KDC-MN-1604Open in new tab →

    Download PDF →

    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.

  • 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.

    Read the full monograph

    The full reference document covers compound identification, discovery and developmental history, mechanism of action, pharmacokinetics, sourcing and quality verification, and a curated reference list. Embedded inline below; download for offline reading.

    KDC-MN-1592Open in new tab →

    Download PDF →

    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.