Muscarinic Agonist Research Articles

Efficacy and Safety of Xanomeline-Trospium Chloride in Schizophrenia

A significant need exists for new antipsychotic medications with different mechanisms of action, greater efficacy, and better tolerability than existing agents. Xanomeline is a dual M1/M4 preferring muscarinic receptor agonist with no direct D2 dopamine receptor blocking activity. KarXT combines xanomeline with the peripheral muscarinic receptor antagonist trospium chloride with the goal of reducing adverse events due to xanomeline-related peripheral muscarinic receptor activation. In prior trials, xanomeline-trospium chloride was effective in reducing symptoms of psychosis and generally well tolerated in people with schizophrenia. To evaluate the efficacy and safety of xanomeline-trospium vs placebo in adults with schizophrenia. EMERGENT-3 (NCT04738123) was a phase 3, multicenter, randomized, double-blind, placebo-controlled, 5-week trial of xanomeline-trospium in people with schizophrenia experiencing acute psychosis, conducted between April 1, 2021, and December 7, 2022, at 30 inpatient sites in the US and Ukraine. Data were analyzed from February to June 2023. Participants were randomized 1:1 to receive xanomeline-trospium chloride (maximum dose xanomeline 125 mg/trospium 30 mg) or placebo for 5 weeks. The prespecified primary end point was change from baseline to week 5 in Positive and Negative Syndrome Scale (PANSS) total score. Secondary outcome measures were change from baseline to week 5 in PANSS positive subscale score, PANSS negative subscale score, PANSS Marder negative factor score, Clinical Global Impression-Severity score, and proportion of participants with at least a 30% reduction in PANSS total score. Safety and tolerability were also evaluated. A total of 256 participants (mean [SD] age, 43.1 [11.8] years; 191 men [74.6%]; 156 of 256 participants [60.9%] were Black or African American, 98 [38.3%] were White, and 1 [0.4%] was Asian) were randomized (125 in xanomeline-trospium group and 131 in placebo group). At week 5, xanomeline-trospium significantly reduced PANSS total score compared with placebo (xanomeline-trospium , -20.6; placebo, -12.2; least squares mean difference, -8.4; 95% CI, -12.4 to -4.3; P < .001; Cohen d effect size, 0.60). Discontinuation rates due to treatment-emergent adverse events (TEAEs) were similar between the xanomeline-trospium (8 participants [6.4%]) and placebo (7 participants [5.5%]) groups. The most common TEAEs in the xanomeline-trospium vs placebo group were nausea (24 participants [19.2%] vs 2 participants [1.6%]), dyspepsia (20 participants [16.0%] vs 2 participants [1.6%]), vomiting (20 participants [16.0%] vs 1 participant [0.8%]), and constipation (16 participants [12.8%] vs 5 participants [3.9%]). Measures of extrapyramidal symptoms, weight gain, and somnolence were similar between treatment groups. Xanomeline-trospium was efficacious and well tolerated in people with schizophrenia experiencing acute psychosis. These findings, together with the previously reported and consistent results from the EMERGENT-1 and EMERGENT-2 trials, support the potential of xanomeline-trospium to be the first in a putative new class of antipsychotic medications without D2 dopamine receptor blocking activity. ClinicalTrials.gov Identifier: NCT04738123.

Agonist-selective activation of individual G-proteins by muscarinic receptors

Selective activation of individual subtypes of muscarinic receptors is a promising way to safely alleviate a wide range of pathological conditions in the central nervous system and the periphery as well. The flexible G-protein interface of muscarinic receptors allows them to interact with several G-proteins with various efficacy, potency, and kinetics. Agonists biased to the particular G-protein mediated pathway may result in selectivity among muscarinic subtypes and, due to the non-uniform expression of individual G-protein alpha subunits, possibly achieve tissue specificity. Here, we demonstrate that novel tetrahydropyridine-based agonists exert specific signalling profiles in coupling with individual G-protein α subunits. These signalling profiles profoundly differ from the reference agonist carbachol. Moreover, coupling with individual Gα induced by these novel agonists varies among subtypes of muscarinic receptors which may lead to subtype selectivity. Thus, the novel tetrahydropyridine-based agonist can contribute to the elucidation of the mechanism of pathway-specific activation of muscarinic receptors and serve as a starting point for the development of desired selective muscarinic agonists.

Muscarinic Receptors in Cardioprotection and Vascular Tone Regulation.

Muscarinic acetylcholine receptors are metabotropic G-protein coupled receptors. Muscarinic receptors in the cardiovascular system play a central role in its regulation. Particularly M2 receptors slow down the heart rate by reducing the impulse conductivity through the atrioventricular node. In general, activation of muscarinic receptors has sedative effects on the cardiovascular system, including vasodilation, negative chronotropic and inotropic effects on the heart, and cardioprotective effects, including antifibrillatory effects. First, we review the signaling of individual subtypes of muscarinic receptors and their involvement in the physiology and pathology of the cardiovascular system. Then we review age and disease-related changes in signaling via muscarinic receptors in the cardiovascular system. Finally, we review molecular mechanisms involved in cardioprotection mediated by muscarinic receptors leading to negative chronotropic and inotropic and antifibrillatory effects on heart and vasodilation, like activation of acetylcholine-gated inward-rectifier K+-currents and endothelium-dependent and -independent vasodilation. We relate this knowledge with well-established cardioprotective treatments by vagal stimulation and muscarinic agonists. It is well known that estrogen exerts cardioprotective effects against atherosclerosis and ischemia-reperfusion injury. Recently, some sex hormones and neurosteroids have been shown to allosterically modulate muscarinic receptors. Thus, we outline possible treatment by steroid-based positive allosteric modulators of acetylcholine as a novel pharmacotherapeutic tactic. Keywords: Muscarinic receptors, Muscarinic agonists, Allosteric modulation, Cardiovascular system, Cardioprotection, Steroids.

KarXT: Combination of Xanomeline and Trospium

KarXT is an oral, research-stage M1/M4-preferring muscarinic agonist that is being developed to treat psychiatric and neurological conditions, such as schizophrenia and Alzheimer’s disease-related psychosis. It is a combination of the muscarinic agonist xanomeline and the muscarinic antagonist trospium. Idea behind this psychopharmaceutical is to preferentially stimulate muscarinic receptors in the central nervous system and to unlock the therapeutic potential of xanomeline, while minimizing adverse effects observed in prior studies. All in all, KarXT is the first potential medication of its kind with a genuinely distinctive dual mechanism that treats symptoms of severe mental illness without relying on the dopaminergic or serotonergic pathway. If approved, this strategy could offer people with serious mental illnesses a different kind of therapy and positively influence their lives.

Nicotinic and Muscarinic Acetylcholine Receptor Agonists Counteract Cognitive Impairment in a Rat Model of Doxorubicin-Induced Chemobrain via Attenuation of Multiple Programmed Cell Death Pathways.

Chemotherapy causes undesirable long-term neurological sequelae, chemotherapy-induced cognitive impairment (CICI), or chemobrain in cancer survivors. Activation of programmed cell death (PCD) has been proposed to implicate in the development and progression of chemobrain. Neuronal apoptosis has been extensively recognized in experimental models of chemobrain, but little is known about alternative forms of PCD in response to chemotherapy. Activation of acetylcholine receptors (AChRs) is emerging as a promising target in attenuating a wide variety of the neuronal death associated with neurodegeneration. Thus, this study aimed to investigate the therapeutic capacity of AChR agonists on cognitive function and molecular hallmarks of multiple PCD against chemotherapy neurotoxicity. To establish the chemobrain model, male Wistar rats were assigned to receive six doses of doxorubicin (DOX: 3mg/kg) via intraperitoneal injection. The DOX-treated rats received either an a7nAChR agonist (PNU-282987: 3mg/kg/day), mAChR agonists (bethanechol: 12mg/kg/day), or the two as a combined treatment. DOX administration led to impaired cognitive function via neuroinflammation, glial activation, reduced synaptic/blood-brain barrier integrity, defective mitochondrial ROS-detoxifying capacity, and dynamic imbalance. DOX insult also mediated hyperphosphorylation of Tau and simultaneously induced various PCD, including apoptosis, necroptosis, and pyroptosis in the hippocampus. Concomitant treatment with either PNU-282987, bethanechol, or a combination of the two potently attenuated neuroinflammation, mitochondrial dyshomeostasis, and Tau hyperphosphorylation, thereby suppressing excessive apoptosis, necroptosis, and pyroptosis and improving cognitive function in DOX-treated rats. Our findings suggest that activation of AChRs using their agonists effectively protected against DOX-induced neuronal death and chemobrain.

Adreno-Muscarinic Synergy of Contractile Responses From Human Hyperplastic Prostate.

Adreno-muscarinic synergy, a supra-additional contractile response to simultaneous application of α-adrenoreceptor and muscarinic receptor agonists, is a feature of several lower urinary tract regions that have dual sympathetic and parasympathetic innervation. We tested the hypothesis that synergy is also a feature of prostate tissue obtained from men with benign prostatic enlargement. Isolated tissue strips were dissected from prostate 'chips', collected after transurethral prostate resection procedures for in vitro experiments, to measure isometric tension at 36°C. Added separately to the superfusate, phenylephrine and carbachol generated contractions with mean pEC50 (-log10EC50) values of 5.36 and 5.58, respectively, although phenylephrine maximal responses were about six-fold greater. In the presence of carbachol, the mean phenylephrine pEC50 was significantly increased to 5.84 and maximal response increased by 28%; overall, a significant synergistic response was demonstrated. The synergistic response was reduced by muscarinic receptor antagonists, most potently by the M3-selective agent 4-DAMP (1,1-dimethyl-4-diphenylacetoxypiperidinium iodide), and less so by M2 and M1-selective inhibitors gallamine and pirenzepine, but with an overall profile indicating M3/M2 mediation of the synergistic response. The magnitude of the synergistic response was variable between prostate chips that provided isolated preparations suggesting regional heterogenicity, although their zonal origin could not be determined. These experiments show that adreno-muscarinic contractile synergy is a feature of human hyperplastic prostate tissue. This has implications for the use of a combination therapy of α-blockers and anti-muscarinic agent to relieve secondary symptoms associated with benign prostatic hyperplasia, at least in men who can tolerate antimuscarinics without a risk of retention.

Long-acting B-2 agonists (LABA) or long-acting muscarinic antagonists (LAMA): which one may be the first option in group A COPD patients?

Long-acting muscarinic antagonists (LAMA) or beta-2 agonists (LABA) have been recommended for symptom control in group A COPD patients as a first-line bronchodilator treatment in GOLD guidelines. However, there is no mention of priority/superiority between the two treatment options. We aimed to compare the effectiveness of these treatments in this group. The study cohort was formed of all subjects from six pulmonology clinics with an initial diagnosis of COPD who were new users of a LAMA or LABA from January 2020 to December 2021. Seventy-six group A COPD patients, in whom LABA or LAMA therapy had been started in the last 1month as a first-line treatment, were included in our study. Participants were evaluated with spirometry, COPD Assessment Test (CAT), mMRC scale, and St. George Respiratory Questionnaire (SGRQ) for three times (baseline, 6-12th months). There were 76 group A COPD patients with LAMA (67.1%) and LABA (32.9%). The number of patients who improved in CAT score at the end of the first year was significantly higher in patients using LAMA than those using LABA (p = 0.022); the improvement at minimum clinically important difference (MCID) in CAT score of LAMA group at 1st year was also significant (p = 0.044). SGRQ total and impact scores were found to be statistically lower at 1st year compared to baseline in patients using LAMA (p = 0.010 and 0.006, respectively). Significant improvement was detected in CAT and SGRQ scores at the 6th month visit in the LAMA group having emphysema (p = 0.032 and 0.002, respectively). According to significant improvements in CAT and SGRQ score, LAMA may be preferred over LABA as a bronchodilator agent in group A COPD patients, especially in emphysema-dominant phenotype.

Development and characterization of niosomes loaded mucoadhesive biodegradable ocular inserts for extended release of pilocarpine HCl

Abstract Background Pilocarpine HCl is a non-selective muscarinic receptor agonist that is prescribed for the treatment of glaucoma. The use of pilocarpine conventional eye drops is associated with several side effects, such as loss of visual acuity, and the need for several applications due to rapid drainage away via the nasolacrimal duct, especially for elderly people. Such adverse effects can lead to low patient compliance and poor clinical outcomes. Therefore, the aim of this project was to develop, optimise and characterise a biodegradable pilocarpine HCl ocular insert using niosomes as a drug delivery vehicle. To achieve that, various polymers such as hydroxypropyl methylcellulose (HPMC), polyvinyl alcohol (PVA), and a blend of both were investigated to prepare the ocular inserts using solvent casting technique. The niosomes of pilocarpine HCl were prepared using span-60 and cholesterol by thin film hydration method. The produced noisome-loaded ocular inserts were characterised using various analytical techniques, including Fourier Transform Infrared (FTIR), X-ray Diffractions (XRD), thermal analysis, particle size analysis, weight and content uniformity, surface pH and drug release profile, among others. Results The results indicated that drug-free ocular inserts of the two polymers (HPMC + PVA) were better than single polymer-based ocular inserts (HPMC or PVA alone). The formed niosomes demonstrated good entrapment efficiency of 49.7% ± 7.0, with an average particle size of 325.7 ± 3.5 nm. The FTIR analysis showed no interaction between the compositions of niosomes. Four optimal formulations with various co-polymer ratios and pilocarpine content were further evaluated. Pilocarpine-containing niosomes-loaded ocular inserts provided uniformity in pilocarpine content (89–96%), with 34.8% moisture content and an average pH of 7. The release profile of niosomes-loaded inserts demonstrated an initial burst release within 2 h ranging from 26.54% (T4) to 41.22% (T2), and continuous sustained release for the next 24 h (68.32 ± 5.11% (T4) to 82.11 ± 6.01% (T2)). Conclusions This work successfully optimised biodegradable ocular inserts containing slow-release pilocarpine HCl encapsulated in niosomes for the treatment of glaucoma without dose dumping, resulting in a user-friendly drug delivery system. Graphical abstract

Differential effects of intra-RMTg infusions of pilocarpine or 4-DAMP on regulating depression- and anxiety-like behaviors

Depression and anxiety are associated with dysfunction of the mesolimbic dopamine system. The rostromedial tegmental nucleus (RMTg) is predominantly composed of GABAergic neurons that exhibit dense projections and strongly inhibit mesolimbic dopaminergic neurons, proposed as a major “brake” for the system. Consequently, the RMTg may be a crucial brain region for regulating these emotions. The central cholinergic system, particularly the muscarinic receptors, plays an important regulatory role in depression and anxiety. M3 muscarinic receptors are distributed on GABAergic neurons in the RMTg, but their involvement in the regulation of depression and anxiety remains uncertain. This study aimed to examine the effects of RMTg M3 muscarinic receptors on regulating depression- and anxiety-like behaviors in adult male Wistar rats, as assessed through the forced swim, tail suspension, and elevated plus maze tests. The results showed that intra-RMTg injections of the M1/M3 muscarinic receptors agonist, pilocarpine (3, 10, and 30 μg/side), or the M3 muscarinic receptors antagonist, 4-DAMP (0.5, 1, and 2 μg/side), did not alter the immobility time in the forced swim and tail suspension tests. Additionally, pilocarpine (30 μg/side) decreased time spent in open arms and increased time in closed arms in the elevated plus maze; while 4-DAMP (1 and 2 μg/side) played the opposite role by increasing time spent in open arms and decreasing time in closed arms. These findings suggest that RMTg M3 muscarinic receptors have differential effects on regulating depression- and anxiety-like behaviors. Enhancing or inhibiting these receptors can produce anxiogenic or anxiolytic effects, but have no impact on depression-like behavior. Therefore, RMTg M3 muscarinic receptors are involved in regulating anxiety and may be a potential therapeutic target for anxiolytic drugs.

The potential of muscarinic M1 and M4 receptor activators for the treatment of cognitive impairment associated with schizophrenia.

Cognitive impairment is a core symptom of schizophrenia and a major determinant of poor long-term functional outcomes. Despite considerable efforts, we do not yet have any approved pharmacological treatments for cognitive impairment associated with schizophrenia (CIAS). A combination of advances in pre-clinical research and recent clinical trial findings have led to a resurgence of interest in the cognition-enhancing potential of novel muscarinic acetylcholine receptor (mAChR) agonists in schizophrenia. This article provides an overview of the scientific rationale for targeting M1 and M4 mAChRs. We describe the evolution of neuroscience research on these receptors since early drug discovery efforts focused on the mAChR agonist xanomeline. This work has revealed that M1 and M4 mAChRs are highly expressed in brain regions that are implicated in cognition. The functional significance of M1 and M4 mAChRs has been extensively characterized in animal models via use of selective receptor subtype compounds through neuronal and non-neuronal mechanisms. Recent clinical trials of a dual M1/M4 mAChR agonist show promising, replicable evidence of potential pro-cognitive effects in schizophrenia, with several other mAChR agonists in clinical development.

Muscarinic Receptors as Targets for Metronomic Therapy in Ovarian Cancer

Aim: In this study, the effects of muscarinic acetylcholine receptor (mAChR) agonist carbachol on the proliferation of cisplatin-resistant (A2780cis) and cisplatin-free (SKOV-3) ovarian cancer cell line were for the first time investigated to further evaluate the potential therapeutic effect of metronomic chemotherapy.&#x0D; Material and Methods: The inhibitory effect of carbachol on cell proliferation was detected using the xCELLigence Real-Time Cell Analyzer (RTCA) dual plate (DP) system. A preliminary study was conducted to determine the dose of carbachol 100 µM, cisplatin 1 µM, and two combination studies were carried out with 100 µM carbachol + cisplatin 1 µM and 100 µM carbachol + 10 µM atropine, over cancer cells without drugs was used as the control group. The cell proliferation curve was monitored for 96 hours. The cell index value of inhibition in cell proliferation was automatically measured every hour for each well using RTCA 1.2.1 software.&#x0D; Results: Co-administration of carbachol with cisplatin caused a decrease in cell number in both A2780cis and SKOV-3 cell lines in a time-dependent manner (p

Cognitive-Enhancing Effects of Acetylcholine Receptor Agonists in Group-Housed Cynomolgus Monkeys Who Drink Ethanol.

The cognitive impairments that are often observed in patients with alcohol use disorder (AUD) partially contribute to the extremely low rates of treatment initiation and adherence. Brain acetylcholine receptors (AChR) mediate and modulate cognitive and reward-related behavior, and their distribution can be altered by long-term heavy drinking. Therefore, AChRs are promising pharmacotherapeutic targets for treating the cognitive symptoms of AUD. In the present study, the procognitive efficacy of two AChR agonists, xanomeline and varenicline, were evaluated in group-housed monkeys who self-administered ethanol for more than 1 year. The muscarinic AChR antagonist scopolamine was used to disrupt performance of a serial stimulus discrimination and reversal (SDR) task designed to probe cognitive flexibility, defined as the ability to modify a previously learned behavior in response to a change in reinforcement contingencies. The ability of xanomeline and varenicline to remediate the disruptive effects of scopolamine was compared between socially dominant and subordinate monkeys, with lighter and heavier drinking histories, respectively. We hypothesized that subordinate monkeys would be more sensitive to all three drugs. Scopolamine dose-dependently impaired performance on the serial SDR task in all monkeys at doses lower than those that produced nonspecific impairments (e.g., sedation); its potency did not differ between dominant and subordinate monkeys. However, both AChR agonists were effective in remediating the scopolamine-induced deficit in subordinate monkeys but not in dominant monkeys. These findings suggest xanomeline and varenicline may be effective for enhancing cognitive flexibility in individuals with a history of heavy drinking. SIGNIFICANCE STATEMENT: Procognitive effects of two acetylcholine (ACh) receptor agonists were assessed in group-housed monkeys who had several years' experience drinking ethanol. The muscarinic ACh receptor agonist xanomeline and the nicotinic ACh receptor agonist varenicline reversed a cognitive deficit induced by the muscarinic ACh receptor antagonist scopolamine. However, this effect was observed only in lower-ranking (subordinate) monkeys and not higher-ranking (dominant monkeys). Results suggest that ACh agonists may effectively remediate alcohol-induced cognitive deficits in a subpopulation of those with alcohol use disorder.

Efficacy and safety of the muscarinic receptor agonist KarXT (xanomeline–trospium) in schizophrenia (EMERGENT-2) in the USA: results from a randomised, double-blind, placebo-controlled, flexible-dose phase 3 trial

New treatments with new mechanisms are urgently needed for people with schizophrenia. Xanomeline is a dual M1 and M4-preferring muscarinic receptor agonist that does not block D2 dopamine receptors, unlike all currently approved treatments for schizophrenia. Xanomeline-trospium (KarXT) combines xanomeline with the peripherally restricted muscarinic receptor antagonist trospium chloride with the goal of ameliorating xanomeline-related adverse events associated with peripheral muscarinic receptors. The EMERGENT-2 trial aimed to assess the efficacy and safety of KarXT in people with schizophrenia experiencing acute psychosis. EMERGENT-2 was a randomised, double-blind, placebo-controlled, flexible-dose, 5-week, inpatient, phase 3 trial in people with schizophrenia. Participants were adults aged 18-65 years with a diagnosis of schizophrenia who had a recent worsening of psychosis warranting hospital admission, a Positive and Negative Syndrome Scale (PANSS) score of 80 or higher, and a Clinical Global Impression-Severity score of 4 or higher. The participants were recruited from 22 inpatient sites in the USA, and were randomly assigned (1:1) to KarXT or placebo twice per day. Participants randomly assigned to KarXT received 50 mg xanomeline and 20 mg trospium twice per day for the first 2 days and then 100 mg xanomeline and 20 mg trospium twice per day for days 3-7. Beginning on day 8, KarXT dosing was flexible with an optional increase to 125 mg xanomeline and 30 mg trospium twice per day and the option to return to 100 mg xanomeline and 20 mg trospium based on tolerability. The primary endpoint was change from baseline to week 5 in PANSS total score. Efficacy analyses used the modified intention-to-treat population (all randomly assigned participants who received at least one trial medication dose and had at least one post-baseline PANSS assessment). Least squares mean change from baseline, SE, and least squares mean difference between the KarXT and placebo groups at week 5, along with the 95% CI and two-sided p values were calculated for the primary and secondary continuous efficacy endpoints. Safety analyses included all participants receiving at least one trial medication dose and used descriptive statistics. This trial is registered with ClinicalTrials.gov (NCT04659161). From Dec 16, 2020, to April 13, 2022, of 407 people who were screened, 252 participants meeting enrolment criteria were randomly assigned to the KarXT (n=126) or placebo (n=126). Baseline PANSS total scores were 98·3 (KarXT; n=126) and 97·9 (placebo; n=125). The trial met the primary endpoint with a mean change from baseline to week 5 in PANSS total score that favoured KarXT (-21·2 points, SE 1·7) versus placebo (-11·6 points, 1·6; least squares mean difference -9·6; 95% CI -13·9 to -5·2; p<0·0001, Cohen's d effect size=0·61). All secondary endpoints were also met, and favoured KarXT versus placebo (p<0·05). The most common adverse events with KarXT versus placebo were constipation (27 [21%] vs 13 [10%]), dyspepsia (24 [19%] vs 10 [8%]), headache (17 [14%] vs 15 [12%]), nausea (24 [19%] vs seven [6%]), vomiting (18 [14%] vs one [1%]), hypertension (12 [10%] vs one [1%]), dizziness (11 [9%] vs four [3%]), gastro-oesophageal reflux disease (eight [6%] vs zero [0%]), and diarrhoea (seven [6%] vs four [3%]). Treatment-emergent adverse event rates of extrapyramidal motor symptoms (KarXT, zero [0%] vs placebo, zero [0%]), akathisia (one [1%] vs one [1%]), weight gain (zero [0%] vs one [1%]), and somnolence (six [5%] vs five [4%]) were similar between the KarXT and placebo groups, as were adverse event-related discontinuation rates (nine [7%] vs seven [6%]). In the EMERGENT-2 trial, KarXT was effective in reducing positive and negative symptoms and was generally well tolerated. These results support the potential for KarXT to represent a new class of effective and well tolerated antipsychotic medicines based on activating muscarinic receptors, not the D2 dopamine receptor-blocking mechanism of all current antipsychotic medications. Results from additional trials, including the identical EMERGENT-3 trial and the 52-week, open-label EMERGENT-4 and EMERGENT-5 trials, will provide additional information on the efficacy and safety of KarXT in people with schizophrenia. Karuna Therapeutics.

Population-Based Characterization of the Pharmacokinetics and Food Effect of ANAVEX3-71, a Novel Sigma-1 Receptor and Allosteric M1 Muscarinic Receptor Agonist in Development for Treatment of Frontotemporal Dementia, Schizophrenia, and Alzheimer Disease.

Pharmacokinetic (PK) data from 28 subjects who received 5-200-mg single ascending doses of ANAVEX3-71, formerly AF710B, were analyzed to characterize the PK of ANAVEX3-71 and its M8 metabolite. PK data from 12 subjects who received 160mg ANAVEX3-71 under fed and fasted conditions were analyzed to characterize the effect of food on the PK of the drug and its M8 metabolite. PK was characterized using the standard 2-stage approach and the nonlinear mixed-effects modeling approach. Dose proportionality was determined using the power model. Two- and 3-compartment linear PK models were tested for the characterization of the PK of ANAVEX3-71 and its M8 metabolite. The PK of ANAVEX3-71 is linear, dose proportional, and time invariant. The drug is rapidly eliminated with a mean (standard deviation) apparent terminal elimination half-life of 3.56 (4.09)hours, while the M8 metabolite was eliminated with a mean (standard deviation) apparent terminal elimination half-life of 6.59 (1.64)hours. The population PK model was used to investigate the effects of covariates on the PK of ANAVEX3-71 and M8. Age, weight, and creatinine clearance were not explanatory of the variability in apparent clearance and apparent volume of the central compartment of ANAVEX3-71. Food had no effect on the PK of ANAVEX3-71 and its M8 metabolite.

Design of ADEPT‐2, a phase 3, parallel group study to evaluate KarXT [xanomeline‐trospium] as a treatment for psychosis associated with Alzheimer’s disease

AbstractBackgroundPsychosis represents a major unmet medical need in patients with Alzheimer’s disease (AD) dementia. With no approved medications for AD dementia psychosis (ADP), current treatment relies on off‐label uses of antipsychotics with limited efficacy and significant safety concerns. Xanomeline is an M1/M4 preferring muscarinic receptor agonist that has previously been shown to have antipsychotic effects in subjects with AD (Bodick et al., 1997). While xanomeline had promising efficacy for potentially treating psychosis in AD, cholinergic adverse events limited further clinical development of xanomeline. KarXT is an investigational treatment that combines xanomeline with trospium, an FDA‐approved non‐specific muscarinic receptor antagonist. Unlike xanomeline, trospium does not measurably cross the blood‐brain barrier, providing a mechanism to mitigate peripheral cholinergic effects of xanomeline while maintaining its muscarinic receptor agonist activities in the brain.MethodsADEPT‐2 trial is a phase 3, randomized, double‐blind, placebo‐controlled, parallel group study to evaluate the safety and efficacy of KarXT for the treatment of ADP. Subjects aged 55‐90 years with moderate to severe psychosis associated with mild to severe AD dementia will be enrolled into the study. Eligible subjects will be randomized to receive either KarXT or placebo in a double‐blinded manner for 14 weeks and subjects who complete the study will be eligible to participate in a one‐year, open‐label safety extension study.ResultsThe primary efficacy endpoint of the study is change from Randomization to End of Treatment in the Neuropsychiatric Inventory‐Clinical (NPI‐C): Hallucinations and Delusions (H+D) score and the key secondary efficacy endpoint is change from Randomization to End of Treatment in the Cohen‐Mansfield Agitation Inventory (CMAI). The safety endpoints include the evaluation of safety and tolerability of KarXT compared with placebo in subjects with ADP. The study is planned to start in 2023 and will enroll approximately 360 subjects with psychosis associated with AD dementia.ConclusionADEPT‐2 is designed to assess the safety and efficacy of KarXT for the treatment of psychosis in patients with AD dementia. If ADEPT‐2 is successful, KarXT has the potential to be the first in a new class of pharmacologic treatment for AD psychosis based on muscarinic receptor agonism.

8-[(4-benzylpiperazin-1-yl)methyl]-3-(2-chlorophenyl)-7-hydroxy-chromen-4-one is an activator of contractile activity of intestinal smooth muscles with reversible M2 cholinomimetic properties

Background. Several pathologies (such as diabetes mellitus, Parkinson’s and Alzheimer’s diseases, multiple sclerosis, etc.) are accompanied by degeneration of cholinergic neurons, which are key regulators of the contractile function of the gastrointestinal tract walls, leading to atony and paresis. An effective strategy for normalizing the lack of contractile function of visceral SM is the use of drugs - selective agonists of muscarinic acetylcholine receptors (mAChRs) of the M2 subtype. The high similarity of the structure of the agonist-binding sites of different subtypes of mAChRs causes problems to develop selective ligands for these receptors. Nowadays, there is an urgent necessity to develop selective agonists of M2 subtype receptors as pharmacological tools for laboratory research and promising drugs. The aim of the present research was to investigate the effect of the 8-[(4-benzylpipe­razin-1-yl)methyl]-3-(2-chlorophenyl)-7-hydroxy-chromen-4-one (compound 1), which was in silico predicted to bind mAChRs, on the contractile activity of rat caecum circular smooth muscle. Materials and Methods. The research was carried out on rats. The contractile activity was studied tensometrically in the isometric mode on preparations of the circular smooth muscles of the caecum of Wistar rats. The kinetic properties of individual spontaneous contractions of SM preparations were determined in accordance with the method of multivariate mechanokinetic analysis with the calculation of mechanokinetic parameters for the phases of contraction and relaxation: time (τ0, τC and τR), force (Fmax, FC and FR), velocity (VC and VR) and impulse (Imax, IC and IR). The kinetic properties of acetylcholine-induced contractions were analyzed by calculating the normalized maximum velocities of the contraction (Vnc) and relaxation (Vnr) phases. Results. It was found that compound 1 caused an increase in the amplitude of acetylcholine-induced contractions; this effect was eliminated by preincubation of SM with the mAChRs M2 subtype inhibitor AF-DX 116. It was revealed that compound 1 (0.1–50 μM) also has the ability to significantly activate the functional activity of colonic SM in a dose-dependent manner, increasing the force and frequency of spontaneous contractions, as well as their mechanokinetic parameters. It was found that the presence of compound 1 (0.1 μM) in the solution washing the smooth muscle for a long time leads to a significant increase in the amplitude and frequency of spontaneous contractions, which tends to reach a stationary mode after 40 minutes of its action. The effect of compound 1 was stable for at least an hour of application to the caecum, and was reversible and significantly eliminated by washing the SM. Conclusions. Compound 1 stimulates the contractile activity of the cecal smooth muscle and exhibits M2 cholinergic properties.

Functional characterization of three G protein-coupled acetylcholine receptors in parasitic nematode Trichinella spiralis

The physiological significance of metabotropic acetylcholine receptors in parasitic nematodes remains largely unexplored. Here, three different Trichinella spiralis G protein-coupled acetylcholine receptors (TsGAR-1, -2, and -3) were identified in the genome of T. spiralis. The phylogenetic analyses showed that TsGAR-1 and -2 receptors belong to a distinct clade specific to invertebrates, while TsGAR-3 is closest to the cluster of mammalian-type muscarinic acetylcholine receptors (mAChR). The mRNA of TsGAR-1, -2, and -3 was detected in muscle larvae, newborn larvae, and adults. The functional aequorin-based assay in Chinese hamster ovary cells revealed that all three types of T. spiralis GARs trigger the Gq/11 pathway upon activation of the receptor with the acetylcholine ligand. TsGAR-1 and TsGAR-2 showed atypical affinity with classical muscarinic agonists, while TsGAR-3 was sensitive to all muscarinic agonists tested. High concentrations of propiverine antagonist blocked the activities of all three TsGARs, while atropine and scopolamine antagonists effectively inhibited only TsGAR-3. Our data indicate that the distinct pharmacological profile of TsGAR-1 and -2 receptors, as well as the phylogenetic distance between them and their mammalian orthologs, place them as attractive targets for the development of selective anthelmintic drugs interfering with nematodes’ cholinergic system.

Three‐Photon Infrared Stimulation of Endogenous Neuroreceptors in Vivo

AbstractTo interrogate neural circuits and crack their codes, in vivo brain activity imaging must be combined with spatiotemporally precise stimulation in three dimensions using genetic or pharmacological specificity. This challenge requires deep penetration and focusing as provided by infrared light and multiphoton excitation, and has promoted two‐photon photopharmacology and optogenetics. However, three‐photon brain stimulation in vivo remains to be demonstrated. We report the regulation of neuronal activity in zebrafish larvae by three‐photon excitation of a photoswitchable muscarinic agonist at 50 pM, a billion‐fold lower concentration than used for uncaging, and with mid‐infrared light of 1560 nm, the longest reported photoswitch wavelength. Robust, physiologically relevant photoresponses allow modulating brain activity in wild‐type animals with spatiotemporal and pharmacological precision. Computational calculations predict that azobenzene‐based ligands have high three‐photon absorption cross‐section and can be used directly with pulsed infrared light. The expansion of three‐photon pharmacology will deeply impact basic neurobiology and neuromodulation phototherapies.

Three-Photon Infrared Stimulation of Endogenous Neuroreceptors in Vivo.

To interrogate neural circuits and crack their codes, in vivo brain activity imaging must be combined with spatiotemporally precise stimulation in three dimensions using genetic or pharmacological specificity. This challenge requires deep penetration and focusing as provided by infrared light and multiphoton excitation, and has promoted two-photon photopharmacology and optogenetics. However, three-photon brain stimulation in vivo remains to be demonstrated. We report the regulation of neuronal activity in zebrafish larvae by three-photon excitation of a photoswitchable muscarinic agonist at 50 pM, a billion-fold lower concentration than used for uncaging, and with mid-infrared light of 1560 nm, the longest reported photoswitch wavelength. Robust, physiologically relevant photoresponses allow modulating brain activity in wild-type animals with spatiotemporal and pharmacological precision. Computational calculations predict that azobenzene-based ligands have high three-photon absorption cross-section and can be used directly with pulsed infrared light. The expansion of three-photon pharmacology will deeply impact basic neurobiology and neuromodulation phototherapies.

Vasodilators activate the anion channel TMEM16A in endothelial cells to reduce blood pressure.

Systemic blood pressure is acutely controlled by total peripheral resistance as determined by the diameter of small arteries and arterioles, the contractility of which is regulated by endothelial cells lining the lumen of blood vessels. We investigated the physiological functions of the chloride (Cl-) channel TMEM16A in endothelial cells. TMEM16A channels generated calcium (Ca2+)-activated Cl- currents in endothelial cells from control (TMEM16Afl/fl) mice that were absent in those from mice with tamoxifen-inducible, endothelial cell-specific knockout of TMEM16A (TMEM16A ecKO). TMEM16A currents in endothelial cells were activated by the muscarinic receptor agonist acetylcholine and an agonist of the Ca2+ channel TRPV4, which localized in nanoscale proximity with TMEM16A as assessed by single-molecule localization imaging of endothelial cells. Acetylcholine stimulated TMEM16A currents by activating Ca2+ influx through surface TRPV4 channels without altering the nanoscale properties of TMEM16A and TRPV4 surface clusters or their colocalization. In pressurized arteries, activation of TMEM16A channels in endothelial cells induced by acetylcholine; TRPV4 channel stimulation; or intraluminal ATP, another vasodilator, produced hyperpolarization and dilation. Furthermore, deficiency of TMEM16A channels in endothelial cells resulted in increased systemic blood pressure in conscious mice. These data indicate that vasodilators stimulate TRPV4 channels, leading to Ca2+-dependent activation of nearby TMEM16A channels in endothelial cells to produce arterial hyperpolarization, vasodilation, and reduced blood pressure. Thus, TMEM16A is an anion channel in endothelial cells that regulates arterial contractility and blood pressure.