Category: Uncategorized

  • 7-Hydroxymitragynine

    Plain-language summaryIntrigue 60 / 100

    7-Hydroxymitragynine is the more potent mu-opioid agonist alkaloid in kratom and is also a metabolite of mitragynine. It is sold as a concentrated alkaloid product with greater opioid activity than whole kratom. Not stocked by Kodiac. This monograph is provided for research and educational reference.

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 Kodiac editorial, not peer-reviewed.

    Terpenoid indole alkaloid with mu-opioid receptor partial agonism and G-protein biased signaling

    A potent oxidative metabolite of mitragynine from Mitragyna speciosa (kratom) distinguished by mu-opioid receptor partial agonism with G-protein biased signaling, oral analgesic activity exceeding morphine potency, and an emerging regulatory landscape reflecting both therapeutic promise and abuse liability.

    Abstract

    7-Hydroxymitragynine (7-OH) is a terpenoid indole alkaloid isolated from the leaves of Mitragyna speciosa Korth. (kratom), first characterized by Ponglux, Takayama, and colleagues in 1994 as a minor constituent comprising less than 2 percent of the total alkaloid content of Thai kratom leaf material [1]. The compound is the C7-hydroxylated derivative of mitragynine, the principal alkaloid of kratom, and is generated both as a natural biosynthetic product in the plant and as a hepatic metabolite of mitragynine through cytochrome P450 3A (CYP3A) isoform-mediated oxidation in mammalian systems [2, 3]. 7-Hydroxymitragynine binds the mu-opioid receptor (MOR) with high affinity (Ki approximately 7 to 70 nM depending on the assay system and radioligand employed), approximately 5- to 46-fold greater than mitragynine, and produces antinociception in rodent hot-plate and tail-flick models at potencies approximately 13-fold greater than morphine on a weight basis after subcutaneous administration and with superior oral bioactivity [4, 5]. The compound functions as a partial agonist at the mu-opioid receptor, with G-protein biased signaling that results in minimal recruitment of beta-arrestin-2, a downstream effector linked to opioid-induced respiratory depression, constipation, and tolerance in the beta-arrestin hypothesis of opioid pharmacology [6, 7]. At delta-opioid (DOR) and kappa-opioid (KOR) receptors, 7-hydroxymitragynine acts as a competitive antagonist, a selectivity profile that distinguishes it from classical full opioid agonists such as morphine and fentanyl [8].

    The pharmacokinetic profile of 7-hydroxymitragynine in humans has been characterized in healthy volunteer studies of oral kratom administration. Maximum plasma concentrations are achieved approximately 1.2 to 2.0 hours after ingestion, with an elimination half-life of approximately 2.5 to 5 hours after single dosing that extends to approximately 24 hours with repeated administration [9, 10]. The compound is formed hepatically from mitragynine through CYP3A4-mediated oxidation; co-administration of the CYP3A4 inhibitor itraconazole reduces 7-hydroxymitragynine Cmax by approximately 56 percent and AUC by 43 percent while increasing mitragynine exposure 1.5-fold, confirming the CYP3A4 dependence of the metabolic conversion [10]. Preclinical studies demonstrate that chronic administration of 7-hydroxymitragynine produces opioid-type physical dependence, tolerance, and naloxone-precipitated withdrawal in mice, with cross-tolerance to morphine [11]. Respiratory depression occurs at potencies approximately 3-fold greater than morphine, though the ceiling effect characteristic of partial agonism may limit the magnitude of respiratory suppression relative to full agonists at equianalgesic doses [12].

    The regulatory landscape for 7-hydroxymitragynine is rapidly evolving. In July 2025, the United States Food and Drug Administration recommended that the Drug Enforcement Administration schedule synthetic and concentrated 7-hydroxymitragynine as a Schedule I controlled substance, while indicating that natural kratom leaf products are not the focus of the scheduling recommendation [13]. Several U.S. states, including Florida, Louisiana, Mississippi, and Colorado, have independently scheduled concentrated 7-hydroxymitragynine products [13]. The compound is not approved for any therapeutic indication in any jurisdiction. This monograph reviews the chemistry, biosynthesis, and semisynthesis of 7-hydroxymitragynine; the opioid receptor pharmacology with emphasis on biased signaling; the human and animal pharmacokinetic record; the preclinical analgesic, tolerance, and dependence evidence; the limited clinical and epidemiological data; sourcing and quality verification; reconstitution and handling; stack-interaction considerations; adverse events and safety signals; and a comparative assessment of five kratom-derived or structurally related opioid analgesic candidates against 7-hydroxymitragynine on five competency standards.

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

  • Abaloparatide

    Plain-language summaryIntrigue 58 / 100

    Abaloparatide, sold as Tymlos, is a modified analog of parathyroid hormone-related protein (a relative of PTH) with substitutions at nine positions designed to make it bind the PTH1 receptor with selectivity for the transient signaling state. The functional consequence is more anabolic and less catabolic effect compared to teriparatide, theoretically offering better bone formation with less bone resorption. Head-to-head ACTIVE trial data showed similar fracture reduction to teriparatide with a different side effect profile. Approved by the FDA in 2017, it occupies the same niche as teriparatide for severe osteoporosis. Not stocked by Kodiac. This monograph is provided for research and educational reference.

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

    Synthetic parathyroid hormone-related protein (PTHrP) analog and selective PTH1 receptor agonist with preferential RG-conformation binding

    A 34-amino-acid synthetic analog of human parathyroid hormone-related protein (1-34) engineered for selective activation of the RG conformation of the PTH type 1 receptor, producing transient osteoanabolic cAMP signaling with reduced bone resorption and hypercalcemia relative to teriparatide, approved for the treatment of osteoporosis in postmenopausal women and men at high fracture risk.

    Abstract

    Abaloparatide (BA058) is a synthetic 34-amino-acid peptide analog of human parathyroid hormone-related protein (PTHrP) (1-34) that acts as a selective agonist at the parathyroid hormone type 1 receptor (PTH1R), a class B G protein-coupled receptor expressed on osteoblasts and osteocytes. The compound was rationally designed to exploit conformational selectivity at PTH1R: abaloparatide binds the G protein-coupled RG conformation with an IC50 of approximately 0.20 nM and the G protein-independent R0 conformation with an IC50 of approximately 316 nM, yielding a 1,600-fold RG/R0 selectivity ratio that exceeds native PTHrP(1-36) (110-fold), native PTH(1-34) (12-fold), and the long-acting analog LA-PTH (2.2-fold). This selectivity produces a transient downstream cAMP signaling response following receptor activation, which, when delivered as a once-daily intermittent subcutaneous injection, preferentially stimulates osteoblast-mediated bone formation with lesser stimulation of osteoclast-mediated bone resorption and a lower incidence of hypercalcemia than teriparatide (recombinant PTH(1-34)), the first-in-class parathyroid hormone receptor agonist for osteoporosis.

    The compound shares 76% amino acid sequence homology with native PTHrP(1-34) and 41% homology with native PTH(1-34). The first 22 amino acids are identical to PTHrP(1-22); positions 23 through 34 carry eight substitutions, including an alpha-aminoisobutyric acid (Aib) residue at position 29, introduced to constrain the C-terminal alpha-helix and enhance peptide stability and receptor binding selectivity. The molecular formula is C174H300N56O49 with a molecular weight of approximately 3,960 daltons. The compound is administered as a once-daily 80 microgram subcutaneous injection into the periumbilical abdominal region. Pharmacokinetics after subcutaneous dosing are characterized by rapid absorption (median Tmax approximately 0.51 hours), an absolute bioavailability of approximately 36%, a volume of distribution of approximately 50 liters, plasma protein binding of approximately 70%, and an elimination half-life of approximately 1 hour, with clearance proceeding through nonspecific proteolytic degradation to smaller peptide fragments followed by renal excretion.

    Clinical efficacy was established in the pivotal ACTIVE trial (Abaloparatide Comparator Trial In Vertebral Endpoints), an 18-month, international, randomized, double-blind, placebo- and active-controlled Phase 3 study in 2,463 postmenopausal women with osteoporosis, in which abaloparatide 80 microgram daily reduced the risk of new morphometric vertebral fractures by 86% relative to placebo (0.58% versus 4.22%) and nonvertebral fractures by 43% (2.7% versus 4.7%). The subsequent ACTIVExtend trial demonstrated that sequential treatment with abaloparatide followed by alendronate maintained fracture risk reduction and further increased bone mineral density over a combined 43-month observation period. The ATOM trial extended efficacy to men with osteoporosis, demonstrating lumbar spine bone mineral density gains of 8.48% versus 1.17% on placebo at 12 months. The compound received United States Food and Drug Administration approval on April 28, 2017, for postmenopausal women with osteoporosis at high fracture risk (marketed as Tymlos), with an expanded indication for men with osteoporosis approved in December 2022. European Medicines Agency approval was granted in December 2022 under the trade name Eladynos. A transdermal solid microstructured transdermal system (sMTS) formulation is in clinical development as an alternative to subcutaneous injection. Treatment duration is limited to a cumulative lifetime maximum of 2 years owing to a dose- and time-dependent increase in osteosarcoma incidence observed in preclinical rodent carcinogenicity studies, a class effect shared with teriparatide.

    This monograph reviews the chemistry, synthesis, and structural pharmacology of abaloparatide; the molecular mechanism of PTH1R conformational selectivity and downstream signaling; comprehensive pharmacokinetics; preclinical pharmacology in ovariectomized and orchiectomized rodent models; the clinical evidence base across the ACTIVE, ACTIVExtend, and ATOM trials; sourcing and quality verification for research applications; reconstitution and handling; stack-interaction considerations; the adverse-event and safety profile including the osteosarcoma signal and cardiovascular safety analysis; and a structured comparative assessment of five alternative bone-active agents (teriparatide, romosozumab, denosumab, zoledronic acid, and raloxifene) against abaloparatide on five competency standards.

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

  • Agmatine

    Plain-language summaryIntrigue 55 / 100

    Agmatine is a naturally occurring small molecule made in the body from arginine. It modulates several systems including NMDA receptors, nitric oxide, and imidazoline receptors. Used as a supplement for nerve pain and mood. Not stocked by Kodiac. This monograph is provided for research and educational reference.

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

    Endogenous polyamine neuromodulator with multi-target activity at NMDA receptors, imidazoline receptors, alpha-2 adrenoceptors, and nitric oxide synthase

    A decarboxylated arginine metabolite and endogenous neuromodulator distinguished by concurrent NMDA receptor channel blockade, imidazoline receptor agonism, selective inducible nitric oxide synthase inhibition, and alpha-2 adrenoceptor activation, with emerging clinical evidence in neuropathic pain, depression, and neuroprotection.

    Abstract

    Agmatine (4-aminobutylguanidine) is an endogenous cationic amine produced by the decarboxylation of L-arginine via the mitochondrial enzyme arginine decarboxylase. First isolated in 1910 by the Nobel laureate Albrecht Kossel from herring sperm protamine hydrolysates, agmatine was rediscovered in 1994 as an endogenous mammalian neuromodulator synthesized, stored in synaptic vesicles, and released in a calcium-dependent manner from neurons in the hippocampus, hypothalamus, locus coeruleus, and other brain regions. The compound operates through a pharmacologically unusual multi-target profile: it produces voltage-dependent blockade of NMDA receptor-gated cation channels at an intrachannel pore site (IC50 approximately 300 micromolar); it binds with high affinity to imidazoline I1 receptors (Kd approximately 0.7 micromolar) and I2 receptors (Kd approximately 1 micromolar); it activates alpha-2 adrenoceptors (Kd approximately 4 micromolar); and it competitively inhibits inducible nitric oxide synthase (Ki approximately 220 micromolar) with selectivity over the neuronal and endothelial isoforms. This composite mechanism produces neuroprotective, analgesic, antidepressant, and anti-inflammatory activity across a broad range of preclinical models, including excitotoxic and ischemic neuronal injury, traumatic brain injury, neuropathic and inflammatory pain, and behavioral models of depression and anxiety.

    Clinical evidence, though still early-phase and limited in scale, has demonstrated efficacy of oral agmatine sulfate in lumbar disc-associated radiculopathy in a randomized, double-blind, placebo-controlled trial at 2,670 mg per day for 14 days, with statistically significant pain reduction versus placebo [1]. A pilot open-label case series in painful small fiber neuropathy reported approximately 46 percent mean pain reduction over two months at the same dose [2]. A 2026 prospective open-label case series at Massachusetts General Hospital reported preliminary evidence for agmatine sulfate augmentation in treatment-resistant obsessive-compulsive disorder, with 40 percent of patients achieving clinically meaningful improvement on the Yale-Brown Obsessive Compulsive Scale [3]. Preclinical antidepressant-like activity has been demonstrated in the forced swimming test and tail suspension test across multiple laboratories, mediated through NMDA receptor blockade, nitric oxide synthase inhibition, and AMPA receptor and mTOR signaling activation. The compound modulates opioid pharmacology in a biphasic manner: it potentiates acute morphine analgesia while preventing the development of analgesic tolerance and physical dependence, a profile that has attracted substantial research interest in the context of the opioid crisis.

    Safety data are favorable. A long-term safety case report documented 5 years of continuous daily intake at 2.67 g agmatine sulfate with no adverse events, and postmarketing surveillance of 1,015 individuals consuming the same regimen for periods of 3 weeks to 3 years identified no adverse events [4]. Clinical trial adverse events have been limited to mild, transient gastrointestinal symptoms (nausea, diarrhea, abdominal discomfort) at the highest studied doses. The compound is commercially available as a dietary supplement (agmatine sulfate) in multiple jurisdictions. This monograph reviews the chemistry, biosynthesis, and multi-target pharmacology of agmatine; the pharmacokinetic profile including oral bioavailability and CNS distribution; the preclinical and clinical evidence base across neuropathic pain, depression, neuroprotection, and opioid modulation; sourcing and quality considerations; reconstitution and handling; stack interactions; adverse-event signal; and a comparative assessment of five mechanistically related compounds against agmatine on five competency standards.

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

  • Amantadine

    Plain-language summaryIntrigue 60 / 100

    Amantadine started life in 1968 as an oral antiviral for influenza A and was later discovered to help Parkinson disease patients, an entirely accidental finding that led to its current main role. It works through several mechanisms at once: weak NMDA glutamate receptor blockade (similar to memantine), dopamine release, and dopamine reuptake inhibition. Today it is most useful for the involuntary movements (dyskinesias) that develop after years of L-DOPA therapy, and for cognitive recovery after traumatic brain injury where it has the strongest evidence base of any drug. The flu indication has largely been abandoned because of widespread viral resistance. Not stocked by Kodiac. This monograph is provided for research and educational reference.

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

    Adamantane-derived multi-target neurotherapeutic agent with weak NMDA receptor antagonism, sigma-1 receptor agonism, and indirect dopaminergic activity

    A tricyclic adamantane amine originally developed as an influenza A antiviral, subsequently repositioned for Parkinson’s disease and levodopa-induced dyskinesia, distinguished by a polypharmacological profile spanning NMDA receptor antagonism, sigma-1 receptor agonism, dopaminergic facilitation, and nicotinic acetylcholine receptor modulation.

    Abstract

    Amantadine (1-adamantanamine) is a small-molecule adamantane derivative that has undergone three distinct phases of clinical development since its original synthesis in the 1960s: as the first synthetic antiviral agent active against influenza A virus through blockade of the M2 ion channel protein; as an antiparkinsonian agent discovered serendipitously in 1968 and subsequently approved for the treatment of drug-induced extrapyramidal reactions and as adjunctive therapy in Parkinson’s disease; and, most recently, as a delayed-release and extended-release formulation (Gocovri) approved by the United States Food and Drug Administration in 2017 for the treatment of levodopa-induced dyskinesia in Parkinson’s disease. The compound occupies a distinctive position in clinical neuropharmacology by virtue of a polypharmacological profile that engages multiple molecular targets at therapeutically relevant concentrations. At the N-methyl-D-aspartate (NMDA) receptor, amantadine acts as a weak, non-competitive, open-channel blocker that accelerates channel closure during channel block, producing glutamatergic modulation at concentrations achievable with standard oral dosing. At the sigma-1 receptor, amantadine acts as an agonist with a Ki of approximately 7.44 micromolar, a mechanism that has been linked to the modulation of dopaminergic neurotransmission including enhancement of tyrosine hydroxylase activity, facilitation of striatal dopamine release, and inhibition of dopamine reuptake. The compound also functions as a negative allosteric modulator of alpha-4-beta-2 and alpha-7 nicotinic acetylcholine receptors, with IC50 values in the low-micromolar range, and exerts additional effects on potassium channels, aromatic amino acid decarboxylase, and glial-cell-derived neurotrophic factor expression.

    The clinical evidence base for amantadine now spans six decades and includes approved indications in Parkinson’s disease (both as monotherapy for mild symptoms and as adjunctive therapy for levodopa-induced dyskinesia), drug-induced extrapyramidal reactions, and influenza A prophylaxis and treatment (now largely obsolete owing to widespread viral resistance). Off-label applications with meaningful clinical support include acceleration of functional recovery in traumatic brain injury with disorders of consciousness, as demonstrated in the landmark Giacino et al. (2012) randomized placebo-controlled trial published in the New England Journal of Medicine; management of fatigue in multiple sclerosis; and reduction of chorea in Huntington disease. Pharmacokinetics are characterized by high oral bioavailability (86 to 90 percent), minimal hepatic metabolism with predominantly renal excretion of unchanged drug, a plasma elimination half-life of approximately 12 hours in subjects with normal renal function (extending to 7 to 10 days in severe renal impairment), and the absence of significant cytochrome P450 involvement. The adverse-event profile includes central nervous system effects (insomnia, dizziness, hallucinations, confusion), peripheral edema, the distinctive dermatological finding of livedo reticularis, and, at supratherapeutic doses or in overdose, QT prolongation and cardiac arrhythmias. This monograph reviews the chemistry, synthesis, and structural class of amantadine; the multi-target molecular pharmacology in mechanistic detail; comprehensive pharmacokinetics; the clinical evidence base across all approved and investigational indications; sourcing, reconstitution, and handling considerations for laboratory work; stack-interaction implications; adverse-event signal; and a comparative assessment of five alternative agents (memantine, rimantadine, budipine, safinamide, and istradefylline) against amantadine on five competency standards.

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

  • ACP-105

    Plain-language summaryIntrigue 38 / 100

    ACP-105 is a tricyclic SARM from Acadia Pharmaceuticals that binds the androgen receptor with high affinity and shows the typical SARM profile of muscle and bone effects with reduced prostate activity in castrated rat models. Acadia briefly explored cognitive applications based on androgen receptor expression in the prefrontal cortex and hippocampus, but development never reached human trials. There are no published pharmacokinetic data in people. It is sold as a research chemical primarily on the strength of its name appearing in old patent literature. The evidence base is thin even by SARM standards. Not stocked by Kodiac. This monograph is provided for research and educational reference.

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

    Nonsteroidal selective androgen receptor modulator (SARM) with partial agonist activity and tissue-selective anabolic profile

    A chlorinated aryl nitrile selective androgen receptor modulator discovered at ACADIA Pharmaceuticals through receptor selection and amplification technology screening, distinguished by partial agonist activity at the androgen receptor, tissue-selective anabolic effects on muscle and bone with minimal prostatic stimulation, and preclinical neuroprotective activity in irradiation and Alzheimer’s disease models.

    Abstract

    ACP-105 (2-chloro-4-[(3-endo)-3-hydroxy-3-methyl-8-azabicyclo[3.2.1]oct-8-yl]-3-methylbenzonitrile) is a nonsteroidal selective androgen receptor modulator (SARM) identified in 2006 at ACADIA Pharmaceuticals AB through high-throughput screening employing receptor selection and amplification technology (R-SAT) and published in the Journal of Medicinal Chemistry in 2009 as the lead compound of a novel aryl nitrile series [1]. The compound binds the androgen receptor with high affinity (pEC50 of 9.0 at the wild-type human androgen receptor and 9.4 at the clinically relevant T877A mutant) and functions as a partial agonist relative to the full agonist activity of testosterone and dihydrotestosterone [1]. In vitro, ACP-105 is reported to be as potent as testosterone in androgen receptor functional assays without measurable interaction at other steroid hormone receptors, including estrogen, progesterone, glucocorticoid, and mineralocorticoid receptors. In vivo, in a two-week chronic study in castrated male rats, the compound improved anabolic parameters (levator ani muscle mass) at approximately 66 percent of the efficacy of testosterone while producing only approximately 21 percent of the androgenic stimulation of the prostate, yielding a favorable anabolic-to-androgenic dissociation ratio of approximately 3:1 [1, 2].

    The compound crosses the blood-brain barrier with a reported brain-to-plasma ratio of 2.7, a property that has motivated investigation in central nervous system models [3, 4]. In a 2011 study by Dayger et al., subcutaneous administration of ACP-105 at 1 mg/kg/day to female C57BL/6J mice protected against 137-cesium irradiation-induced impairment of sensorimotor function on the rotarod and enhanced cued fear conditioning in both sham-irradiated and irradiated animals, with immunohistochemical evidence of region-specific modulation of microtubule-associated protein 2 (MAP-2) in the sensorimotor cortex [3]. In a 2013 study by George et al. in gonadectomized male triple-transgenic Alzheimer’s disease mice (3xTg-AD), ACP-105 at 10 mg/kg administered intraperitoneally four days per week reduced anxiety-like behavior when given alone and, when co-administered with the selective estrogen receptor beta agonist AC-186, improved long-term spatial memory on the Morris water maze, increased the amyloid-beta degrading enzymes neprilysin and insulin-degrading enzyme, and reduced brain amyloid-beta 40 and amyloid-beta 42 levels after seven months of treatment [4].

    Predicted and in silico absorption, distribution, metabolism, and excretion (ADME) profiling indicates high gastrointestinal absorption (94 to 100 percent), moderate lipophilicity (LogP 3.0 to 3.5), strong plasma protein binding (77 to 99 percent), and primary hepatic metabolism through CYP3A4 with secondary contributions from CYP2C19, CYP1A2, CYP2C9, and CYP2D6 [5]. In vivo metabolite identification studies in rats, horses, and humans have collectively characterized 21 or more phase I and phase II metabolites, predominantly monohydroxylated and bishydroxylated species formed on the azabicyclic ring system, along with glucuronide conjugates [6, 7, 8]. Predicted plasma half-life is approximately 1.18 hours, though this value derives from computational models and has not been confirmed in formal human pharmacokinetic studies [5].

    ACP-105 has never entered human clinical trials. No Phase 1, Phase 2, or Phase 3 studies are registered or reported. The compound was nominated as a development candidate by ACADIA Pharmaceuticals in February 2006 for potential treatment of muscle wasting and osteoporosis, and preclinical data were presented at the Experimental Biology 2008 meeting, but development was subsequently discontinued. The compound is classified as a prohibited substance under World Anti-Doping Agency (WADA) regulations since 2008, and adverse analytical findings for ACP-105 have appeared in routine sports doping control samples [6, 9]. Research-grade ACP-105 is available from multiple chemical suppliers at greater than 98 percent purity. This monograph reviews the chemistry, structure-activity relationships, and characterization of ACP-105; the androgen receptor partial agonist mechanism and tissue selectivity; the available absorption, distribution, metabolism, and excretion data; the preclinical pharmacology in musculoskeletal and central nervous system models; the absence of clinical evidence; sourcing and quality verification; reconstitution and handling; stack interaction considerations; adverse event and safety signals; and a comparative assessment of five alternative SARM compounds against ACP-105 on five competency standards.

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

  • Allopregnanolone

    Plain-language summaryIntrigue 80 / 100

    Allopregnanolone is a neurosteroid metabolite of progesterone that powerfully potentiates GABA-A receptors. Recombinant allopregnanolone (brexanolone) is FDA-approved for postpartum depression. Not stocked by Kodiac. This monograph is provided for research and educational reference.

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

    Endogenous neurosteroid and positive allosteric modulator of GABA-A receptors with dual synaptic and extrasynaptic activity

    An endogenous pregnane neurosteroid and the most potent known positive allosteric modulator of GABA-A receptors, reduced to clinical practice as brexanolone (Zulresso) for postpartum depression and serving as the pharmacophore template for the orally bioavailable derivative zuranolone.

    Abstract

    Allopregnanolone (3alpha-hydroxy-5alpha-pregnan-20-one; 3alpha,5alpha-tetrahydroprogesterone; brexanolone) is an endogenous C21 pregnane neurosteroid biosynthesized from progesterone by sequential 5alpha-reductase and 3alpha-hydroxysteroid oxidoreductase activity in the central nervous system, adrenal cortex, ovary, and placenta. First isolated from adrenal tissue in 1938 and identified as a potent positive allosteric modulator of GABA-A receptors by Majewska and colleagues in 1986, allopregnanolone occupies a singular position in neuropsychopharmacology as the most potent endogenous modulator of inhibitory GABAergic neurotransmission. At low nanomolar concentrations, the compound allosterically enhances GABA-gated chloride currents at both synaptic (alpha-beta-gamma-containing) and extrasynaptic (alpha-beta-delta-containing) GABA-A receptor subtypes; at higher micromolar concentrations, it directly gates the chloride channel in the absence of GABA. The extrasynaptic receptor preference distinguishes allopregnanolone from benzodiazepines and underlies its characteristic anxiolytic, anticonvulsant, sedative-hypnotic, and antidepressant pharmacology.

    The translational trajectory of allopregnanolone spans more than eight decades. Selye reported the anesthetic properties of pregnane steroids in 1941. Baulieu and colleagues proposed the “neurosteroid” concept in 1981 after demonstrating de novo brain synthesis independent of peripheral endocrine sources. Majewska et al. (1986) established the GABA-A receptor mechanism. Paul and Purdy (1992) coined “neuroactive steroid” to encompass synthetic analogs acting through non-genomic receptor modulation. The modern clinical program began at Sage Therapeutics, which developed an intravenous formulation of synthetic allopregnanolone (designated SAGE-547, later brexanolone) for postpartum depression (PPD). Two Phase 3 randomized, double-blind, placebo-controlled trials (Meltzer-Brody et al. 2018) demonstrated rapid, clinically meaningful, and sustained reductions in Hamilton Depression Rating Scale (HAM-D) scores following a 60-hour continuous intravenous infusion. The United States Food and Drug Administration approved brexanolone (Zulresso) in March 2019 as the first therapy specifically indicated for PPD, subject to a Risk Evaluation and Mitigation Strategy (REMS) program requiring inpatient administration with continuous pulse oximetry monitoring owing to the risks of excessive sedation and loss of consciousness.

    A parallel clinical program led by Roberta Diaz Brinton at the University of Arizona has investigated allopregnanolone as a regenerative therapeutic for Alzheimer’s disease, grounded in preclinical demonstrations that the compound promotes hippocampal neural stem cell proliferation, neurogenesis, oligogenesis, and restoration of cognitive function in transgenic Alzheimer’s models and wild-type aged mice. A Phase 1b/2a multiple ascending dose trial (NCT02221622) in early Alzheimer’s disease reported safety, tolerability, and exploratory neuroimaging signals including preservation of hippocampal volume and functional connectivity changes after 12 weeks of intermittent intravenous dosing. Additional clinical investigations have evaluated allopregnanolone in fragile X-associated tremor/ataxia syndrome (FXTAS), status epilepticus, traumatic brain injury, and essential tremor.

    The principal pharmacokinetic limitation of endogenous allopregnanolone is negligible oral bioavailability (less than 5 percent), necessitating intravenous, subcutaneous, or intramuscular administration. This limitation drove development of orally bioavailable synthetic analogs, most notably zuranolone (SAGE-217), a deuterated allopregnanolone analog approved by the FDA in August 2023 for PPD, and ganaxolone (3beta-methyl allopregnanolone), approved for seizures associated with CDKL5 deficiency disorder in March 2022. Allopregnanolone is metabolized by extra-hepatic non-CYP pathways, principally keto-reduction, glucuronidation, and sulfation, with an elimination half-life of approximately 9 hours after intravenous infusion, a volume of distribution of approximately 3 L/kg, and greater than 99 percent plasma protein binding. The compound is a controlled substance (Schedule IV in the United States). This monograph reviews the chemistry, biosynthesis, receptor pharmacology, pharmacokinetics, preclinical and clinical evidence base across all studied indications, sourcing and quality verification, reconstitution and handling, stack-interaction considerations, adverse-event profile, and a structured comparative assessment of five neurosteroid GABA-A receptor modulators against allopregnanolone on five competency standards.

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

  • Acetyl Glutathione

    Plain-language summaryIntrigue 38 / 100

    Acetyl glutathione is glutathione with an acetyl group attached to the cysteine sulfur, marketed in the supplement industry as a way to deliver intact glutathione orally. The proposed rationale is that the acetyl group protects the tripeptide from gastrointestinal proteolysis, allowing absorption of the full molecule rather than just its amino acid components. The case for meaningful intact absorption rests on small studies and biochemical reasoning rather than rigorous human pharmacokinetic data. Cheaper alternatives (NAC and direct oral glutathione) raise comparable cellular glutathione levels by different routes, making the niche for acetyl glutathione narrow. Not stocked by Kodiac. This monograph is provided for research and educational reference.

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

    S-acyl thioester prodrug of reduced glutathione (gamma-L-glutamyl-L-cysteinyl-glycine)

    An acetylated thioester derivative of reduced glutathione engineered to resist gastrointestinal hydrolysis and deliver intact glutathione equivalents to the intracellular compartment via passive membrane permeation and subsequent cytoplasmic thioesterase-mediated deacetylation.

    Abstract

    S-Acetyl-L-glutathione (SAG) is the S-acyl thioester of reduced glutathione (GSH) in which a single acetyl group is conjugated to the sulfhydryl moiety of the cysteine residue, shielding it from oxidation and enzymatic degradation during gastrointestinal transit and systemic circulation. The modification addresses the central pharmacokinetic limitation of oral GSH supplementation: native reduced glutathione is rapidly hydrolyzed by gamma-glutamyltransferase and dipeptidases in the intestinal lumen and brush border, resulting in less than 1 percent systemic bioavailability of the intact tripeptide after oral dosing in humans. By masking the reactive thiol as a thioester, SAG transits the gut mucosa substantially intact, permeates cell membranes by passive diffusion, and is deacetylated intracellularly by cytoplasmic thioesterases to regenerate free reduced glutathione, thereby replenishing the intracellular GSH pool without dependence on de novo synthesis from precursor amino acids.

    The compound was first described in the medicinal chemistry literature as a glutathione S-acyl derivative in the 1970s, with early characterization of its sensitivity to human liver esterases. It entered the nutraceutical research field in the 2000s as a candidate oral glutathione delivery vehicle and has since been the subject of a single-center, single-dose, randomized, open-label, cross-over pharmacokinetic trial in 18 healthy volunteers (Fanelli et al., 2018), multiple preclinical studies in hepatoprotection and oncology, and a comprehensive toxicological safety assessment including bacterial reverse mutation assay, in vitro micronucleus testing, acute oral toxicity, and 13-week repeated-dose oral toxicity studies. The pharmacokinetic trial demonstrated that SAG is rapidly deacetylated to GSH after oral administration, with no quantifiable SAG detected in plasma at any time point; plasma GSH concentrations after SAG administration exhibited higher maximum concentration (Cmax) and area under the curve (AUC) compared to an equimolar dose of a marketed reduced glutathione product, with mean relative bioavailability exceeding that of the reference formulation.

    Preclinical pharmacology has demonstrated hepatoprotective activity against carbon tetrachloride-induced liver injury through restoration of superoxide dismutase activity, glutathione peroxidase activity, and mitochondrial function, with concurrent suppression of the TLR4/NF-kappaB inflammatory cascade and reduction of proinflammatory cytokines TNF-alpha, IL-6, IL-1beta, and MCP-1. In oncology research, SAG selectively induces apoptosis in human lymphoma cell lines (Daudi, Raji, Jurkat) through a paradoxical intracellular GSH depletion mechanism while sparing normal lymphocytes and resistant lymphoma lines (Hut-78), a selectivity that has positioned it as a research tool for mechanism-based apoptosis investigation. The compound is manufactured by selective S-acetylation of reduced glutathione, achievable in a single step with cobalt chloride catalysis in dimethylformamide-trifluoroacetic acid solvent at yields exceeding 90 percent, and is commercially available from multiple research-grade suppliers at purities exceeding 98 percent by HPLC. It is supplied as a white to off-white crystalline powder with a molecular weight of 349.36 g/mol (CAS 3054-47-5), melting point of approximately 202 to 208 degrees Celsius, and stability at ambient temperature in dry storage. This monograph reviews the chemistry, synthesis, pharmacology, pharmacokinetics, preclinical and clinical evidence, sourcing, handling, safety, and comparative assessment of SAG against five alternative glutathione-repletion strategies.

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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.

  • Alfaxalone

    Plain-language summaryIntrigue 68 / 100

    Alfaxalone is a synthetic neurosteroid IV anesthetic, originally combined with alfadolone in the human anesthetic Althesin (withdrawn 1984 after anaphylactoid reactions traced to the Cremophor solubilizer rather than the steroid). It was reformulated with a cyclodextrin solubilizer as Alfaxan and approved for veterinary use in dogs, cats, and rabbits. Structurally it mirrors the endogenous neurosteroid allopregnanolone. Mechanism is positive modulation of GABA-A receptors at a steroid binding site distinct from the benzodiazepine and barbiturate sites, with channel-opening activity at higher concentrations. Cardiovascular and respiratory profiles are favorable for an IV induction agent (less hypotension and apnea than propofol at induction doses), driving widespread veterinary use in cardiac-compromised patients. It serves as the canonical reference compound for synthetic neurosteroid GABA-A pharmacology, underpinning the design of brexanolone, ganaxolone, and zuranolone. Not stocked by Kodiac. This monograph is provided for research and educational reference.

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

    Neuroactive steroid general anesthetic and GABAA receptor positive allosteric modulator

    A synthetic pregnane neurosteroid originally developed by Glaxo as the active component of the intravenous anesthetic Althesin, reformulated in cyclodextrin carriers for veterinary registration and under active clinical investigation for human anesthesia with emerging evidence for neuroprotection and postoperative cognitive preservation.

    Abstract

    Alfaxalone (3-alpha-hydroxy-5-alpha-pregnane-11,20-dione) is a synthetic neuroactive steroid with potent general anesthetic properties mediated principally through positive allosteric modulation and, at higher concentrations, direct activation of gamma-aminobutyric acid type A (GABAA) receptors. First synthesized at the Glaxo UK Pharmacology Department in the late 1960s and introduced in 1971 as the principal active component of the intravenous anesthetic formulation Althesin (CT-1341), alfaxalone was administered in an estimated three million human anesthetic procedures across the United Kingdom, Europe, and other jurisdictions before its withdrawal from human clinical use in 1984 owing to anaphylactoid reactions attributed to the Cremophor EL solubilizing vehicle rather than to the active steroid itself. The compound was subsequently reformulated in 2-hydroxypropyl-beta-cyclodextrin (HPCD) by Jurox Animal Health and re-entered clinical practice as Alfaxan, a veterinary injectable anesthetic registered for induction and maintenance of general anesthesia in dogs and cats in Australia, New Zealand, the United Kingdom, continental Europe, the United States, and other jurisdictions. The HPCD formulation is devoid of the histamine-releasing properties of Cremophor EL and produces rapid-onset, short-duration, non-cumulative anesthesia with a cardiovascular safety profile superior to propofol in published comparative studies.

    Alfaxalone binds at the transmembrane beta-plus/alpha-minus subunit interface of GABAA receptors, a site structurally characterized by X-ray crystallography and cryo-electron microscopy of alpha1-beta3-gamma2 receptor assemblies. At sub-micromolar concentrations the compound potentiates GABA-evoked chloride conductance (positive allosteric modulation); at concentrations exceeding approximately one micromolar it directly gates the chloride channel in the absence of GABA (direct agonism). The composite dose-dependent pharmacology produces a continuum from anxiolysis and sedation through surgical anesthesia. Unlike the endogenous neurosteroid allopregnanolone and unlike classical progestogens, alfaxalone has no measurable activity at glucocorticoid, mineralocorticoid, or progesterone nuclear hormone receptors, a selectivity that simplifies its pharmacological profile and eliminates endocrine confounding in chronic or repeated dosing.

    A second molecular activity, characterized by in vitro studies from the Goodchild laboratory, is activation of the human pregnane X receptor (PXR) with greater efficacy than allopregnanolone. PXR activation drives transcription of brain-derived neurotrophic factor (BDNF) and other neuroprotective gene targets, providing a mechanistic basis for the observation in a double-blind randomized clinical trial that alfaxalone total intravenous anesthesia preserves postoperative serum mature BDNF levels and cognitive function relative to propofol and propofol-sevoflurane comparator arms (Serrao and Goodchild, 2022).

    Pharmacokinetics across species are dominated by rapid hepatic biotransformation. In dogs, plasma clearance after intravenous bolus is approximately 59 mL/kg/min (approaching hepatic blood flow), terminal elimination half-life is approximately 25 minutes, and volume of distribution is approximately 2.4 L/kg. In cats, clearance is approximately 25 mL/kg/min, half-life approximately 45 minutes, and volume of distribution approximately 1.8 L/kg. In the Phase 1 human trial of Phaxan (alfaxalone formulated in sulfobutylether-beta-cyclodextrin), plasma clearance was high and equal to hepatic blood flow, with rapid onset and offset of anesthesia comparable to propofol. The compound does not accumulate on repeated bolus dosing or continuous rate infusion at clinical doses, supporting its use for total intravenous anesthesia.

    Drawbridge Pharmaceuticals has advanced the human formulation (Phaxan) through Phase 1 dose-finding (Goodchild et al., 2019), a Phase 1c randomized double-blind comparison with propofol (Monagle et al., 2015), and a Phase 3 pilot study in hip arthroplasty (Serrao and Goodchild, 2022). Results demonstrate fast-onset, short-duration anesthesia with cognitive recovery comparable to propofol, less cardiovascular depression, less airway obstruction, and no pain on injection. The compound is not currently approved for human use in any jurisdiction. Additional research applications include anticonvulsant activity in refractory status epilepticus models, anxiolytic and sedative-hypnotic effects at sub-anesthetic doses, and neuroprotective activity through the PXR-BDNF pathway.

    This monograph documents the chemistry, synthesis, and stereochemistry of alfaxalone; the GABAA receptor pharmacology in structural and electrophysiological detail; the pregnane X receptor neuroprotective mechanism; comprehensive pharmacokinetics across species; the clinical and veterinary evidence base; sourcing and quality verification for research applications; reconstitution and handling; stack-interaction considerations; the adverse-event and safety signal; and a structured comparative assessment of five alternative intravenous anesthetic or neurosteroid agents (propofol, etomidate, ketamine, brexanolone, ganaxolone) against alfaxalone on five competency standards.

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

  • 5-MeO-DMT

    Plain-language summaryIntrigue 76 / 100

    5-MeO-DMT is a tryptamine psychedelic chemically related to DMT but with strikingly different pharmacology: it prefers the 5-HT1A receptor over 5-HT2A, the opposite of N,N-DMT, which produces a qualitatively distinct experience generally described as an undifferentiated state rather than the visionary content of classical psychedelics. It is concentrated in the parotoid gland secretions of the Sonoran Desert toad (Bufo alvarius), the source of toad medicine ceremonies, and is found in several plants used in South American snuffs. Clinical interest in single-dose treatment for depression and substance use disorders is growing, with several small studies underway. The intensity and brevity of the experience pose unusual clinical and safety challenges. Not stocked by Kodiac. This monograph is provided for research and educational reference.

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

    Indolealkylamine tryptamine psychedelic with preferential 5-HT1A receptor agonism and broad serotonergic activity

    A naturally occurring 5-methoxy-substituted tryptamine distinguished from classical psychedelics by preferential high-affinity 5-HT1A receptor agonism, ultra-short duration of action, and emerging Phase 2 clinical evidence in treatment-resistant depression.

    Abstract

    5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT; CAS 1019-45-0; molecular formula C13H18N2O; molecular weight 218.30 g/mol) is a naturally occurring indolealkylamine tryptamine psychedelic first synthesized by Hoshino and Shimodaira in 1936, subsequently identified as a constituent of Anadenanthera peregrina seeds, Virola species bark resins, and the parotoid gland secretions of the Sonoran Desert toad Incilius alvarius (formerly Bufo alvarius). The compound is pharmacologically distinguished from other tryptamine psychedelics (N,N-dimethyltryptamine, psilocin, bufotenine) by a receptor binding profile that strongly favors the serotonin 5-HT1A receptor (Ki approximately 1.9 to 3 nM) over the 5-HT2A receptor (Ki approximately 900 nM), producing a 300- to 1000-fold selectivity ratio that inverts the binding preference of the classical 5-HT2A-preferring psychedelics. Functional pharmacology demonstrates full agonist activity at 5-HT1A receptors and partial to full agonism at 5-HT2A receptors, with additional binding at the serotonin transporter (SERT), sigma-1 receptors, and trace amine-associated receptor 1 (TAAR1).

    The subjective psychedelic experience produced by inhaled 5-MeO-DMT is characterized by a rapid onset (30 to 60 seconds), intense peak (5 to 15 minutes), and brief total duration (15 to 20 minutes), rendering the compound the shortest-acting of the classical tryptamine psychedelics. The ultra-short duration and the predominance of 5-HT1A-mediated pharmacology produce qualitative differences from 5-HT2A-preferring psychedelics: less visual perceptual distortion, more ego-dissolution and dissociative phenomenology, and high scores on mystical experience questionnaires comparable to high-dose psilocybin.

    Metabolism proceeds through two principal pathways. Monoamine oxidase A (MAO-A) catalyzes oxidative deamination to 5-methoxyindoleacetic acid, the primary inactivation route that accounts for the rapid systemic clearance and the oral inactivity of the compound in the absence of MAO inhibition. Cytochrome P450 2D6 (CYP2D6) catalyzes O-demethylation to bufotenine (5-hydroxy-N,N-dimethyltryptamine), a pharmacologically active metabolite with preferential 5-HT2A receptor affinity. CYP2D6 polymorphism substantially modulates the bufotenine metabolic fraction; poor metabolizers produce less bufotenine but experience prolonged parent compound exposure, while ultrarapid metabolizers generate more bufotenine with potential for additive serotonergic burden. The dual-enzyme metabolic architecture creates clinically significant drug-drug interactions, most critically with MAO inhibitors (harmine, harmaline, moclobemide, phenelzine, tranylcypromine), which increase 5-MeO-DMT systemic exposure 3.6- to 4.4-fold and bufotenine exposure 6.1- to 9.9-fold, with documented risk of serotonin toxicity and fatalities.

    Clinical development is led by GH Research (Dublin), whose inhalable mebufotenin formulation GH001 met the primary endpoint in a randomized, double-blind, placebo-controlled Phase 2b trial in 81 patients with treatment-resistant depression (TRD), demonstrating a placebo-adjusted Montgomery-Asberg Depression Rating Scale (MADRS) reduction of 15.5 points at day 8 and remission rates of 77.8 percent at 6 months in the open-label extension (announced February 2025). A Phase 1/2 open-label trial (Reckweg et al. 2023) in 12 TRD patients reported 87.5 percent remission at day 7 and no serious adverse events. Preclinical pharmacology demonstrates neuroplasticity effects including increased dendritic spine density in mouse medial frontal cortex, increased neurogenesis in the dentate gyrus, and anxiolytic effects in stressed animal models. The compound is classified as Schedule I in the United States, is not approved by any regulatory authority for medical use, and all research applications are subject to controlled substance research licensure. This monograph reviews the chemistry, natural occurrence, dual-enzyme metabolism, receptor pharmacology, pharmacokinetics, preclinical and clinical evidence, safety signal, sourcing, reconstitution, stack interactions, and a comparative assessment of five tryptamine psychedelic candidates against 5-MeO-DMT on five competency standards.

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