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Background and Purpose Experimental Approach Key Results Conclusions and Implications Botulinum neurotoxin type A1 (BoNT/A) is one of the most potent neurotoxins known. At the same time, it is also one of the safest therapeutic agents used for the treatment of several human disorders and in aesthetic medicine. Notwithstanding great effectiveness, strategies to accelerate the onset and prolong BoNT/A action would significantly ameliorate its pharmacological effects with beneficial outcomes for clinical use.Here, we combined BoNT/A with two fast‐acting inhibitors of excitation–contraction coupling inhibitors (ECCI), either the μ‐conotoxin CnIIIC or dantrolene, and tested the effect of their co‐injection on a model of hind‐limb paralysis in rodents using behavioural, biochemical, imaging and electrophysiological assays.The BoNT/A‐ECCI combinations accelerated the onset of muscle relaxation. Surprisingly, they also potentiated the peak effect and extended the duration of the three BoNT/A commercial preparations OnabotulinumtoxinA, AbobotulinumtoxinA and IncobotulinumtoxinA. ECCI co‐injection increased the number of BoNT/A molecules entering motoneuron terminals, which induced a faster and greater cleavage of SNAP‐25 during the onset and peak phases, and prolonged the attenuation of nerve‐muscle neurotransmission during the recovery phase. We estimate that ECCI co‐injection yields a threefold potentiation in BoNT/A pharmacological activity.Overall, our results show that the pharmacological activity of BoNT/A can be combined and synergized with other bioactive molecules and uncover a novel strategy to enhance the neuromuscular effects of BoNT/A without altering the neurotoxin moiety or intrinsic activity, thus maintaining its exceptional safety profile. [ABSTRACT FROM AUTHOR]

Darier disease (DD) is a rare severe acantholytic skin disease caused by mutations in the ATP2A2 gene that encodes for the sarco/endoplasmic reticulum calcium ATPase isoform 2 (SERCA2). SERCA2 maintains endoplasmic reticulum calcium homeostasis by pumping calcium into the ER, critical for regulating cellular calcium dynamics and cellular function. To date, there is no treatment that specifically targets the disease mechanisms in DD. Dantrolene sodium (Dl) is a ryanodine receptor antagonist that inhibits calcium release from ER to increase ER calcium levels and is currently used for non-dermatological indications. In this study, we first identified dysregulated genes and molecular pathways in DD patient skin, demonstrating downregulation of cell adhesion and calcium homeostasis pathways, as well as upregulation of ER stress and apoptosis. We then show in various in vitro models of DD and SERCA2 inhibition that Dl aided in the retention of ER calcium and promoted cell adhesion. In addition, Dl treatment reduced ER stress and suppressed apoptosis. Our findings suggest that Dl specifically targets pathogenic mechanisms of DD and may be a potential treatment. Synopsis: In this study we show that Dantrolene, an approved ryanodine receptor antagonist, improved various pathophysiological hallmarks of Darier disease in in vitro models of the disease, demonstrating the potential applicability of the drug as a novel therapy. Dantrolene increases ER calcium levels and improves cell adhesion. Dantrolene partially improves ER stress and reduces apoptosis. In this study we show that Dantrolene, an approved ryanodine receptor antagonist, improved various pathophysiological hallmarks of Darier disease in in vitro models of the disease, demonstrating the potential applicability of the drug as a novel therapy. [ABSTRACT FROM AUTHOR]

Abstract Darier disease (DD) is a rare severe acantholytic skin disease caused by mutations in the ATP2A2 gene that encodes for the sarco/endoplasmic reticulum calcium ATPase isoform 2 (SERCA2). SERCA2 maintains endoplasmic reticulum calcium homeostasis by pumping calcium into the ER, critical for regulating cellular calcium dynamics and cellular function. To date, there is no treatment that specifically targets the disease mechanisms in DD. Dantrolene sodium (Dl) is a ryanodine receptor antagonist that inhibits calcium release from ER to increase ER calcium levels and is currently used for non-dermatological indications. In this study, we first identified dysregulated genes and molecular pathways in DD patient skin, demonstrating downregulation of cell adhesion and calcium homeostasis pathways, as well as upregulation of ER stress and apoptosis. We then show in various in vitro models of DD and SERCA2 inhibition that Dl aided in the retention of ER calcium and promoted cell adhesion. In addition, Dl treatment reduced ER stress and suppressed apoptosis. Our findings suggest that Dl specifically targets pathogenic mechanisms of DD and may be a potential treatment.

Background: Malignant hyperthermia (MH) is a rare pharmacogenetic disorder that can lead to a life‐threatening reaction during general anaesthesia with triggering agents. Prompt life‐saving treatment includes the immediate administration of the antidote dantrolene. This study investigated Swedish healthcare providers' awareness and adherence to guidelines and recommendations with respect to MH and whether adherence to safe MH‐praxis varies with hospital care‐complexity level and private versus public management form. Method: Agreements and procurement specifications between all 21 Swedish County Councils and privately run surgical care providers were reviewed alongside with questionnaire‐aided collection of information from 62 publicly funded health care providers (both privately and publicly run). Results: No procurement requirement specification or contract contained requirements on anaesthesia or aspects of MH. All publicly run hospitals stocked dantrolene and 28 out of 52 (54%) stocked the recommended amount. Seven out of nine (78%) of the privately run institutions stocked dantrolene, and one stocked the recommended amount. Publicly run hospitals adhered to recommendations to a greater extent than privately run institutions, both with respect to stocking of dantrolene (p =.02) and to stocking the recommended amount (p =.03). Conclusions: Contracts between Swedish county councils and private surgical care subcontractors rarely outline expectations of standards for the safe practice of anaesthesia such as preparedness to handle a life‐threatening MH reaction. Among Swedish publicly funded anaesthesia providers there is room for improvement in adherence to the EMHG guideline on dantrolene availability. Publicly run hospitals seem to have better compliance with these recommendations than privately run institutions. Raising awareness about current guidelines is important to improve safety for known and unknown MH‐susceptible individuals. [ABSTRACT FROM AUTHOR]

BACKGROUD: Endoplasmic reticulum/sarcoplasmic reticulum (ER/SR) is crucial for maintaining intracellular calcium homeostasis due to the calcium‐signaling‐related proteins on its membrane. While ryanodine receptors (RyR) on insect ER/SR membranes are well‐known as targets for diamide insecticides, little is known about other calcium channels. Given the resistance of diamide insecticides, the establishment of molecular screening models targeting RyR or sarco/endoplasmic reticulum calcium ATPase (SERCA) is conducive to the discovery of new insecticidal molecules. RESULTS: The morphological features of Mythimna separata SR have closed vesicles with integrity and high density. The 282 proteins in the SR component contained RyR and SERCA. A measurement model for the release and uptake of calcium was successfully established by detecting calcium ions outside the SR membrane using a fluorescence spectrophotometer. In vitro testing systems using SR vesicles found that diamide insecticides could activate dose‐dependently RyR, with EC50 values of 0.14 μM (Chlorantraniliprole), 0.21 μM (Flubendiamide), and 0.57 μM (Cyantraniliprole), respectively. However, dantrolene inhibited RyR‐mediated calcium release with an IC50 value of 353.9 μM, suggesting that dantrolene can weakly antagonize RyR. Moreover, cyclopiazonic acid significantly reduced the enzyme activity and calcium uptake capacity of SERCA. On the contrary, CDN1163 markedly activated the enzyme activity and improved the calcium transport capacity of SERCA. CONCLUSIONS: SR vesicles can be used to study the function of unknown proteins on the SR membranes, as well as for high‐throughput screening of highly active compounds targeting RyR or SERCA. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Tetanus is a life-threatening, vaccine-preventable disease caused by an endotoxin produced by Clostridium tetani. We report a case of severe tetanus in an adult male with a history of intravenous drug use. The patient presented with a 1-day history of inability to open his jaw and a right lower extremity necrotic wound. Initial management consisted of tetanus toxoid, human tetanus immunoglobulin, antimicrobials and intermittent lorazepam. Due to progressive symptoms, wound debridement and placement of an advanced airway in the operating room ensued. Episodes of tetany were associated with fever, autonomic instability, acute desaturations and preemptive ventilator triggering despite maximum doses of continuous propofol and midazolam. Neuromuscular blockade with cisatracurium was added, resulting in control of tetany. Despite initial control, NMB could not be weaned due to recurrent spasms. Intravenous dantrolene was therefore sought as an alternative antispasmodic. Following an initial load, patient was successfully liberated from cisatracurium. Dantrolene was therefore converted to enteral to facilitate gradual down-titration of intravenous sedatives with subsequent conversion to oral benzodiazepines. After a prolonged hospital course, the patient was able to be discharged home. Dantrolene was thus effectively utilized as an adjunctive antispasmodic agent to facilitate liberation from cisatracurium and continuous sedation. [ABSTRACT FROM AUTHOR]

The effect of Ryanodine receptor2 (RyR2) and its stabilizer on cardiac hypertrophy is not well known. C57/BL6 mice underwent transverse aortic contraction (TAC) or sham surgery were administered dantrolene, the RyR2 stabilizer, or control drug. Dantrolene significantly alleviated TAC-induced cardiac hypertrophy in mice, and RNA sequencing was performed implying calcineurin/NFAT3 and TNF-α/NF-κB/NLRP3 as critical signaling pathways. Further expression analysis and Western blot with heart tissue as well as neonatal rat cardiomyocyte (NRCM) model confirmed dantrolene decreases the activation of calcineurin/NFAT3 signaling pathway and TNF-α/NF-κB/NLRP3 signaling pathway, which was similar to FK506 and might be attenuated by calcineurin overexpression. The present study shows for the first time that RyR2 stabilizer dantrolene attenuates cardiac hypertrophy by inhibiting the calcineurin, therefore downregulating the TNF-α/NF-κB/NLRP3 pathway. Schematic diagram of the mechanism of Dantrolene. Dantrolene attenuates cardiac hypertrophy through inhibition of TNF-α/NF-κB/NLRP3 pathway by downregulating Calcineurin/NFAT3 pathway. [ABSTRACT FROM AUTHOR]

Introduction: The loose-patch clamp technique was first developed and used in native amphibian skeletal muscle (SkM), offering useful features complementing conventional sharp micro-electrode, gap, or conventional patch voltage clamping. It demonstrated the feedback effects of pharmacological modification of ryanodine receptor (RyR)-mediated Ca2+ release on the Na+ channel (Nav1.4) currents, initiating excitation–contraction coupling in native murine SkM. The effects of the further RyR and Ca2+-ATPase (SERCA) antagonists, dantrolene and cyclopiazonic acid (CPA), additionally implicated background tubular-sarcoplasmic Ca2+ domains in these actions. Materials and methods: We extend the loose-patch clamp approach to ion current measurements in murine hippocampal brain slice cornu ammonis-1 (CA1) pyramidal neurons. We explored the effects on Na+ currents of pharmacologically manipulating RyR and SERCA-mediated intracellular store Ca2+ release and reuptake. We adopted protocols previously applied to native skeletal muscle. These demonstrated Ca2+-mediated feedback effects on the Na+ channel function. Results: Experiments applying depolarizing 15 ms duration loose-patch clamp steps to test voltages ranging from −40 to 120 mV positive to the resting membrane potential demonstrated that 0.5 mM caffeine decreased inward current amplitudes, agreeing with the previous SkM findings. It also decreased transient but not prolonged outward current amplitudes. However, 2 mM caffeine affected neither inward nor transient outward but increased prolonged outward currents, in contrast to its increasing inward currents in SkM. Furthermore, similarly and in contrast to previous SkM findings, both dantrolene (10 μM) and CPA (1 μM) pre-administration left both inward and outward currents unchanged. Nevertheless, dantrolene pretreatment still abrogated the effects of subsequent 0.5- and 2-mM caffeine challenges on both inward and outward currents. Finally, CPA abrogated the effects of 0.5 mM caffeine on both inward and outward currents, but with 2 mM caffeine, inward and transient outward currents were unchanged, but sustained outward currents increased. Conclusion: We, thus, extend loose-patch clamping to establish pharmacological properties of murine CA1 pyramidal neurons and their similarities and contrasts with SkM. Here, evoked though not background Ca2+-store release influenced Nav and Kv excitation, consistent with smaller contributions of background store Ca2+ release to resting [Ca2+]. This potential non-canonical mechanism could modulate neuronal membrane excitability or cellular firing rates. [ABSTRACT FROM AUTHOR]

Jiechu Wang,1– 3,&ast; Yao Yu,1,&ast; Ya Gao,1– 3,&ast; Tingting Wan,1– 3 Zhukai Cong,1– 3 Zhengqian Li,1– 3 Yang Zhou,1– 3 Xiaoxiao Wang,4 Luyang Feng,1– 3 Yongzheng Han,1– 3 Jing Zhang,1– 3 Yinyin Qu,1– 3 Xiangyang Guo1– 3 1Department of Anesthesiology, Peking University Third Hospital, Beijing, 100191, People’s Republic of China; 2Beijing Center of Quality Control and Improvement on Clinical Anesthesia, Peking University Third Hospital, Beijing, 100191, People’s Republic of China; 3Anesthesia and Perioperative Medicine Branch of China International Exchange and Promotive Association for Medical and Health Care (CPAM), Beijing, 100191, People’s Republic of China; 4Research Center for Clinical Epidemiology, Peking University Third Hospital, Beijing, 100191, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Xiangyang Guo; Yinyin Qu, Department of Anesthesiology, Peking University Third Hospital, North Garden Road 49, Haidian District, Beijing, 100191, People’s Republic of China, Email puthmzk@hsc.pku.edu.cn; quyinyin@bjmu.edu.cnBackground: Malignant hyperthermia (MH) is a hypermetabolic syndrome with high mortality rates. Early detection and prompt intravenous administration of dantrolene are crucial for effective management of MH. However, there is currently a lack of comprehensive nationwide surveys on the availability of dantrolene and anesthesiologists’ understanding of MH in China.Methods: A nationwide survey was conducted between January 2022 and June 2022. Online questionnaires on the cognition of MH among anesthesiologists in China were sent through social platforms to anesthesiologists in mainland China. Data regarding participants’ perception of MH-related knowledge, availability of domestic dantrolene, and reported MH cases were collected in this study.Results: Responses were collected from a total of 11,354 anesthesiologists representing 31 provinces across the Chinese mainland. Among the 11 scoring questions, the highest accuracy rates were observed for the question regarding therapeutic drugs for MH (99.3%) and the characteristics of MH (98.0%). Conversely, the question pertaining to the earliest clinical signs of MH had the lowest accuracy rate (23.5%). Significant variations were observed in the scores among different professional titles (P=0.003), academic degree (P< 0.001), hospital classification (P< 0.001), and urban hierarchy (P< 0.001). Of the respondents, 919 (8.1%) anesthesiologists reported dantrolene availability in their hospitals, and 631 (5.6%) indicated unclear. A total of 136 hospitals in this survey reported at least one previous case of MH.Conclusion: Mainland China faces challenges such as insufficient experience in diagnosing and treating MH, as well as difficulty in obtaining dantrolene. To improve the public awareness of MH, it is imperative to establish and promote a refined MH training system. Additionally, a streamlined and rapid dantrolene linkage emergency system should be implemented to ensure prompt access to the drug.Keywords: malignant hyperthermia, dantrolene, China, anesthesiologists, survey

Background: Repurposing dantrolene to treat Alzheimer's disease has been shown to be effective in amyloid transgenic mouse models but has not been examined in a model of tauopathy. Objective: The effects of a nanoparticle intranasal formulation, the Eagle Research Formulation of Ryanodex (ERFR), in young adult and aged wild type and PS19 tau transgenic mice was investigated. Methods: The bioavailability of intranasal ERFR was measured in 2 and 9–11-month-old C57BL/6J mice. Blood and brain samples were collected 20 minutes after a single ERFR dose, and the plasma and brain concentrations were analyzed. Baseline behavior was assessed in untreated PS19 tau transgenic mice at 6 and 9 months of age. PS19 mice were treated with intranasal ERFR, with or without acrolein (to potentiate cognitive dysfunction), for 3 months, beginning at 2 months of age. Animal behavior was examined, including cognition (cued and contextual fear conditioning, y-maze), motor function (rotarod), and olfaction (buried food test). Results: The dantrolene concentration in the blood and brain decreased with age, with the decrease greater in the blood resulting in a higher brain to blood concentration ratio. The behavioral assays showed no significant changes in cognition, olfaction, or motor function in the PS19 mice compared to controls after chronic treatment with intranasal ERFR, even with acrolein. Conclusions: Our studies suggest the intranasal administration of ERFR has higher concentrations in the brain than the blood in aged mice and has no serious systemic side effects with chronic use in PS19 mice. [ABSTRACT FROM AUTHOR]

Muscle relaxants and pain killers with their different types are widely used as combination approach for treatment of pain associated with several muscle spasm conditions. A sensitive and simple HPLC-UV detection method was developed in this work for simultaneous assay of Dantrolene (DNT) and co-administrated: Ibuprofen (IBU) and Diclofenac (DIC). After simple protein precipitation, separation was achieved using C18 column (150 × 4.6 mm) with a mobile phase of acidified water with orthophosphoric acid (pH = 3.5) and acetonitrile using gradient elution with a flow rate of 1 mL/min. The DAD was adjusted at 380, 219, 280 and 240 nm to measure DNT, IBU, DIC, and dexamethasone (internal standard), respectively. Linearity was demonstrated over the range from 0.1 to 3 μg/mL, 1 to 40 μg/mL, and 0.1 to 2 μg/mL for DNT, IBU, and DIC, respectively. The validated method was applied successfully to compare the effect of co-administration of IBU or DIC on the pharmacokinetic profile of DNT. [ABSTRACT FROM AUTHOR]

Background: Postoperative cognitive dysfunction (POCD) is a common disorder after general anesthesia in elderly patients, the precise mechanisms of which remain unclear. Methods: We investigated the effect of isoflurane with or without dantrolene pretreatment on intracellular calcium concentration ([Ca2+]i), reactive oxygen species (ROS) production, cellular lactate dehydrogenase (LDH) leak, calpain activity, and cognitive function using the Morris water maze test of young (3 months), middle-aged (12–13 months), and aged (24–25 months) C57BL6/J mice. Results: Aged cortical and hippocampal neurons showed chronically elevated [Ca2+]i compared to young neurons. Furthermore, aged hippocampal neurons exhibited higher ROS production, increased LDH leak, and elevated calpain activity. Exposure to isoflurane exacerbated these markers in aged neurons, contributing to increased cognitive deficits in aged mice. Dantrolene pretreatment reduced [Ca2+]i for all age groups and prevented or significantly mitigated the effects of isoflurane on [Ca2+]i, ROS production, LDH leak, and calpain activity in aged neurons. Dantrolene also normalized or improved age-associated cognitive deficits and mitigated the cognitive deficits caused by isoflurane. Conclusions: These findings suggest that isoflurane-induced cytotoxicity and cognitive decline in aging are linked to disruptions in neuronal intracellular processes, highlighting the reduction of [Ca2+]i as a potential therapeutic intervention. [ABSTRACT FROM AUTHOR]

Context: Ryanodine receptors (RyRs) are large intracellular ligand-gated calcium release ion channels. Mutations in human RyR1 in combination with a volatile anesthetic or muscle relaxant are known to cause leaky RyRs resulting in malignant hyperthermia (MH). This has long been primarily treated with the RyR inhibitory drug dantrolene. Alternatives to dantrolene as a RyR inhibitor may be found through computer-aided drug design. Additionally, molecular dynamics (MD) studies of dantrolene interacting with RyRs may reveal its full mechanism of action. The availability of accurate force field parameters is important for the success of both. Methods: In this study, force field parameters for dantrolene were obtained from the CHARMM General Force Field (CGenFF) program and optimized using the force field toolkit (FFTK) and FFParam programs. The obtained parameters were then validated by a comparison between calculated and experimental IR spectra and normal mode analysis, among other techniques. [ABSTRACT FROM AUTHOR]

IntroductionThe loose-patch clamp technique was first developed and used in native amphibian skeletal muscle (SkM), offering useful features complementing conventional sharp micro-electrode, gap, or conventional patch voltage clamping. It demonstrated the feedback effects of pharmacological modification of ryanodine receptor (RyR)-mediated Ca2+ release on the Na+ channel (Nav1.4) currents, initiating excitation–contraction coupling in native murine SkM. The effects of the further RyR and Ca2+-ATPase (SERCA) antagonists, dantrolene and cyclopiazonic acid (CPA), additionally implicated background tubular-sarcoplasmic Ca2+ domains in these actions.Materials and methodsWe extend the loose-patch clamp approach to ion current measurements in murine hippocampal brain slice cornu ammonis-1 (CA1) pyramidal neurons. We explored the effects on Na+ currents of pharmacologically manipulating RyR and SERCA-mediated intracellular store Ca2+ release and reuptake. We adopted protocols previously applied to native skeletal muscle. These demonstrated Ca2+-mediated feedback effects on the Na+ channel function.ResultsExperiments applying depolarizing 15 ms duration loose-patch clamp steps to test voltages ranging from −40 to 120 mV positive to the resting membrane potential demonstrated that 0.5 mM caffeine decreased inward current amplitudes, agreeing with the previous SkM findings. It also decreased transient but not prolonged outward current amplitudes. However, 2 mM caffeine affected neither inward nor transient outward but increased prolonged outward currents, in contrast to its increasing inward currents in SkM. Furthermore, similarly and in contrast to previous SkM findings, both dantrolene (10 μM) and CPA (1 μM) pre-administration left both inward and outward currents unchanged. Nevertheless, dantrolene pretreatment still abrogated the effects of subsequent 0.5- and 2-mM caffeine challenges on both inward and outward currents. Finally, CPA abrogated the effects of 0.5 mM caffeine on both inward and outward currents, but with 2 mM caffeine, inward and transient outward currents were unchanged, but sustained outward currents increased.ConclusionWe, thus, extend loose-patch clamping to establish pharmacological properties of murine CA1 pyramidal neurons and their similarities and contrasts with SkM. Here, evoked though not background Ca2+-store release influenced Nav and Kv excitation, consistent with smaller contributions of background store Ca2+ release to resting [Ca2+]. This potential non-canonical mechanism could modulate neuronal membrane excitability or cellular firing rates.

Dantrolene sodium (DS) was first introduced as an oral antispasmodic drug. However, in 1975, DS was demonstrated to be effective for managing malignant hyperthermia (MH) and was adopted as the primary therapeutic drug after intravenous administration. However, it is difficult to administer DS intravenously to manage MH. MH is life-threatening, pharmacogenomically related, and induced by depolarizing neuromuscular blocking agents or inhalational anesthetics. All anesthesiologists should know the pharmacology of DS. DS suppresses Ca2+ release from ryanodine receptors (RyRs). RyRs are expressed in various tissues, although their distribution differs among subtypes. The anatomical and physiological functions of RyRs have also been demonstrated as effective therapeutic drugs for cardiac arrhythmias, Alzheimer’s disease, and other RyR-related diseases. Recently, a new formulation was introduced that enhanced the hydrophilicity of the lipophilic DS. The authors summarize the pharmacological properties of DS and comment on its indications, contraindications, adverse effects, and interactions with other drugs by reviewing reference articles.

The objective – to summarize the current literature data on the etiology, pathogenesis, diagnosis and treatment of malignant hyperthermia. The search and analysis of literature data on malignant hyperthermia in the medical information systems PubMed, Сochrane librarу, Cyberleninka for the last 10 years was performed with using the keywords: «malignant hyperthermia», «dantrolene», «general anesthesia», «succinylcholine», «inhalation anesthetics». The search criteria were met by 96 publications. In addition, references to selected articles were manually checked for applicable articles including recent reports of malignant hyperthermia, in addition to works of historical significance. It was shown that malignant hyperthermia develops in susceptible individuals during or after general anesthesia with the use of trigger agents – inhaled halogen-containing anesthetics and succinylcholine. Until recently, the problem of treatment in Russia remained unresolved, since specific therapy for this syndrome was not available. In connection with the official registration of Dantrolene in the Russian Federation, this problem no longer has a life-threatening potential. Doctors should recognize the symptoms of this disease as early as possible in order to quickly begin the pathogenetic treatment of malignant hyperthermia in order to prevent fatal complications. The material is intended for a wide audience of anesthesiologists, resuscitators and surgeons who may encounter this pathology in clinical practice.

Koichi Nisijima1,2 1Department of Psychiatry, Nasukougen Hospital, Nasu-machi, Tochigi, Japan; 2Department of Psychiatry, Jichi Medical University, Shimotuke City, Tochigi, JapanCorrespondence: Koichi Nisijima, Shimotuke City, Tochigi, 329-0433, Japan, Tel/Fax +81-285-44-2411, Email poppo0309@cc9.ne.jpAbstract: Anticholinergic drugs, such as biperiden, benztropine, and diphenhydramine, were used for neuroleptic malignant syndrome (NMS) in the 1980s and 1990s. However, they have not been recommended for pharmacotherapy in NMS since 2000, as they may prevent a decrease in body temperature by suppressing sweating. However, whether anticholinergic drugs actually exacerbate NMS remains unclear. This study highlights the usefulness of anticholinergic drugs, which are no longer attracting attention as current pharmacological treatments for NMS. I treated four NMS patients using anticholinergic drugs. Two patients were treated with biperiden alone, and the other two patients were treated with a combination of biperiden and other drugs, including dantrolene, amantadine, or diazepam. Intramuscular injection of biperiden improved muscle rigidity, tremors, dysphagia, and akinetic mutism. Psychiatrists are familiar with anticholinergic drugs as they are used for antipsychotic-induced akathisia and Parkinsonism. My study suggests that anticholinergic drugs, especially injectable formulations, can be a therapeutic option for NMS.Keywords: anticholinergic drug, dantrolene, intramuscular injection, Parkinsonism

Background: Arsenic can increase the risk of osteoporosis among the population in arsenic–endemic areas compared with the general population in non-endemic areas. And calcium overload is the related mechanisms of arsenic-induced osteoporosis However, there is a relative lack of clinical research on the treatment of arsenic-induced osteoporosis. Dantrolene and 2-APB, as Ca2+ influx inhibitor, can reduce calcium overload and play an important role in the excitation–contraction coupling of skeletal muscle. Therefore, we study the effects of dantrolene and 2-APB on arsenic-induced osteoporosis in this study. Objective: To study the effects of arsenic on the trabeculae of rats, and observe the effects of dantrolene and 2-aminoethoxydiphenyl borate (2-APB) on the trabeculae. Results: Compared with the control group, some indices of micro-CT (BV/TV, Tb.Th, Tb.N, BMD, and DA) and the alkaline phosphatase (ALP) activity of bone marrow stromal cells (BMSCs) decreased, while some indices of micro-CT (Tb.Sp, Tb.Pf, and SMI), biochemical indicators (ALT, AST, ALP, and GGT), and the Ca2+concentration of BMSCs increased in the Sodium arsenite (NaAsO2) group (P < 0.05). Compared with the NaAsO2 group, the indices of micro-CT and biochemical indicators improved, the Ca2+ concentration of BMSCs decreased, and the ALP activity of BMSCs increased in the dantrolene group, 2-APB group and dantrolene + 2-APB group (P < 0.05), especially dantrolene + 2-APB group. Conclusion: NaAsO2 can lead to osteoporosis in rats, dantrolene and 2-APB can reduce the degree of arsenic-induced osteoporosis. [ABSTRACT FROM AUTHOR]

Introduction: The aim of the present work was to elucidate the possible protective role of Verapamil (VPM) and Dantrolene (Da) in controlling experimentally induced early acute pancreatitis (AP) in male albino rats. Materials and Methods: Thirty- two adult male wistar-albino rats were divided randomly into: Group I (Control group; n. 8). Group II ((AP) group; n.24): 8 for each experimental subgroup: Subgroup (IIa) untreated AP: each was injected intraperitoneal (IP) by 250mg L- arginine/100g body weight. Subgroup (IIb) AP treated with VPM: each was pre-treated with VPM (0.25mg/100g body weight) by IP injection an hour before L-arginine induction. Subgroup (IIc) AP treated with Da: each was pre-treated with Da (1mg/100g body weight) by IP injection an hour before induction. Twenty-four hours following L-arginine injection, the rats were sacrificed by cervical dislocation under anesthesia by IP injection of pentobarbital at dose of 50mg/ Kg body weight. Serological assessment of serum lipase and amylase, histological, histochemical, immunohistochemical and morphometric studies were done. Biochemical Study for Malondialdehyde (MDA), catalase, trypsin and Tumor necrosis factor alpha (TNFα) assessment by quantitative polymerase chain reaction (qPCR) were performed. All studies were followed by statistical analysis. Results: Subgroup IIa showed morphological changes indicating inflammation and degeneration that regressed in subgroups IIb & IIc with more obvious regression in subgroup IIb. The mean values of serum (s) amylase and lipase indicated a significant increase in AP subgroup compared to control and treated subgroups also a significant decrease was found in verapamil subgroup versus dantrolene subgroups. Morphometric and biochemical quantitative values were confirmative. Conclusions: Verapamil and Dantrolene therapy proved definite protective effect, more obvious in response to verapamil, in controlling experimentally induced early AP in male albino rats. [ABSTRACT FROM AUTHOR]

Ryanodine receptors (RyRs), the intracellular Ca2+ release channels, are expressed in T lymphocytes and other types of immune cells. Modulation of RyRs has been shown to affect T cell functions in vitro and immune responses in vivo. The effects of modulation of RyRs on the development of autoimmune diseases have not been investigated. Here we studied how modulation of RyRs through administration of RyR inhibitor dantrolene or introducing a gain-of-function RYR1-p.R163C mutation affects clinical progression of experimental autoimmune encephalomyelitis (EAE) in mice, a T cell-mediated autoimmune neuroinflammatory disease. We found that daily intraperitoneal administration of 5 or 10 mg/kg dantrolene beginning at the time of EAE induction significantly reduced the severity of EAE clinical symptoms and dampened inflammation in the spinal cord. The protective effect of dantrolene on EAE was reversible. Dantrolene administration elicited dose-dependent skeletal muscle weakness: mice that received 10 mg/kg dose developed a waddling gait, while 5 mg/kg dantrolene dose administration produced a reduction in four-limb holding impulse values. Mice bearing the gain-of-function RYR1-p.R163C mutation developed the EAE clinical symptoms faster and more severely than wild-type mice. This study demonstrates that RyRs play a significant role in EAE pathogenesis and suggests that inhibition of RyRs with low doses of dantrolene may have a protective effect against autoimmunity and inflammation in humans.

The objective of the present is to present the anesthetic management that occurred before a critical event malignant hyperthermia HM) in an electively scheduled Madden radical mastectomy and which was managed with what was available at that time for not having the drug specific (dantrolene) for this type of event HM. Breast cancer is a complex disease, being the leading cause of death in women worldwide, with 70% occurring in developed countries. Mexico is at an intermediate level, being a health problem with a tendency to rise due to the aging of the population. population and higher prevalence of risk factors. Malignant hyperthermia (MH) is an anesthetic-triggered pharmacogenetic disorder that triggers a massive accumulation of calcium in the sarcoplasm, leading to accelerated metabolism and increased skeletal muscle contractile activity. Leading to a hypermetabolic state showing an increase in body temperature, leading to significant sequelae and high mortality. It was a 40-year-old female with no relevant history for anesthetic procedures, being managed with balanced general anesthesia at 60 minutes present data clinicians that they suggested malignant hyperthermia, being managed. With the available means, obtaining a favorable result from the point of view of morbidity and mortality. [ABSTRACT FROM AUTHOR]

Malignant hyperthermia is a rare but life-threatening pharmacogenetic disorder triggered by exposure to specific anesthetic agents. Although this occurrence could affect virtually any patient during the perioperative time, the pediatric population is particularly vulnerable, and it has a five-fold higher incidence in children compared to adults. In the last few decades, synergistic efforts among leading anesthesiology, pediatrics, and neurology associations have produced new evidence concerning the diagnostic pathway, avoiding unnecessary testing and limiting false diagnoses. However, a personalized approach and an effective prevention policy focused on clearly recognizing the high-risk population, defining perioperative trigger-free hospitalization, and rapid activation of supportive therapy should be improved. Based on epidemiological data, many national scientific societies have produced consistent guidelines, but many misconceptions are common among physicians and healthcare workers. This review shall consider all these aspects and summarize the most recent updates. [ABSTRACT FROM AUTHOR]

Dantrolene binds to the Leu601-Cys620 region of the N-terminal domain of cardiac ryanodine receptor (RyR2), which corresponds to the Leu590-Cys609 region of the skeletal ryanodine receptor, and suppresses diastolic Ca2+ leakage through RyR2. We investigated whether the chronic administration of dantrolene prevented left ventricular (LV) remodeling and ventricular tachycardia (VT) after myocardial infarction (MI) by the same mechanism with the mutation V3599K of RyR2, which indicated that the inhibition of diastolic Ca2+ leakage occurred by enhancing the binding affinity of calmodulin (CaM) to RyR2. A left anterior descending coronary artery ligation MI model was developed in mice. Wild-type (WT) were divided into four groups: sham-operated mice (WT-Sham), sham-operated mice treated with dantrolene (WT-Sham-DAN), MI mice (WT-MI), and MI mice treated with dantrolene (WT-MI-DAN). Homozygous V3599K RyR2 knock-in (KI) mice were divided into two groups: sham-operated mice (KI-Sham) and MI mice (KI-MI). The mice were followed for 12 weeks. Survival was significantly higher in the WT-MI-DAN (73%) and KI-MI groups (70%) than the WT-MI group (40%). Echocardiography, pathological tissue, and epinephrine-induced VT studies showed that LV remodeling and VT were prevented in the WT-MI-DAN and KI-MI groups compared to the WT-MI group. An increase in diastolic Ca2+ spark frequency and a decrease in the binding affinity of CaM to the RyR2 were observed at 12 weeks after MI in the WT-MI group, although significant improvements in these values were observed in the WT-MI-DAN and KI-MI groups. Pharmacological or genetic stabilization of RyR2 tetrameric structure improves survival after MI by suppressing LV remodeling and proarrhythmia. [Display omitted] • Dantrolene, a stabilizer of RyR2, prevented diastolic Ca2+ leakage from RyR2 by enhancing the binding affinity of calmodulin (CaM) to RyR2 in MI. • The mutation V3599K of RyR2 inhibited the diastolic Ca2+ leakage by enhancing the binding affinity of CaM to RyR2 in MI. • Pharmacological or genetic stabilization of tetrameric RyR2 improved survival after MI by suppressing LV remodeling and proarrhythmia. [ABSTRACT FROM AUTHOR]

Introduction: A cerebral vasospasm (CVSP) is a potent vasoconstriction of the cerebral vasculature and the primary cause of morbidity and mortality following a subarachnoid hemorrhage. The middle cerebral artery (MCA) is commonly affected by CVSPs. Concomitant administration of dantrolene and nimodipine synergistically reduces vasospasms in aortic rings from Sprague Dawley rats. To determine if the effects observed in the systemic vasculature extend to the cerebral circulation, we investigated the effect of intravenous administration of dantrolene (2.5 mg/kg) and nimodipine (1 mg/kg and 2 mg/kg) on MCA blood flow velocity (BFV) 7 days after the induction of CVSPs. Methods: Vasospasms were induced by bathing the left common carotid artery with autologous whole blood. Age-matched sham rats were used as controls. BFV, mean arterial pressure (MAP), and heart rate (HR) were measured with a PeriFlux 5000 Laser Doppler System, and a CODA non-invasive blood pressure system, before and after administering the drugs. Morphometric evaluations were also performed to assess vascular alterations. Results: BFV was reduced by 37% with dantrolene alone (n = 6, p ≤ 0.05) and by 27% with 2 mg/kg nimodipine (n = 6, p < 0.05), while it was not affected by 1 mg/kg nimodipine. The combination of 1 mg/kg nimodipine with dantrolene, however, decreased BFV by 35% (from 435.70 ± 21.53 to 284.30 ± 23.13 perfusion units, n = 7, p ≤ 0.05). A similar reduction (31%) was obtained with dantrolene and 2 mg/kg nimodipine (from 536.00 ± 32.61 to 367.80 ± 40.93 perfusion units, n = 6, p ≤ 0.05). Neither MAP nor HR was affected by dantrolene or nimodipine alone. The combination of dantrolene with 2 mg/kg nimodipine, however, decreased MAP and increased HR. Furthermore, 7 days after the induction of vasospasms, lumen area of the left common carotid artery decreased, whereas media thickness and the wall-to-lumen ratio increased when compared to contralateral controls. The latter finding suggests that vascular remodeling was present at this stage. Conclusion: Altogether, our results indicate that 2.5 mg/kg dantrolene significantly reduces BFV in the MCA without altering systemic hemodynamic parameters to a similar extent than the highest dose of nimodipine or the combination of dantrolene and the lowest dose of nimodipine. Therefore, dantrolene may provide a promising alternative to lower the risk, or partially revert, CVSP. [ABSTRACT FROM AUTHOR]

Objective: The aim of this publication was to describe the occurrence of malignant hyperthermia (MH) in the Czech and Slovak populations, including genetic results and reasons for reporting to the MH diagnostic centre. Design: Retrospective observational cohort study. Setting: Academic Centre of Malignant Hyperthermia of Masaryk University. Material and methods: All probands referred to our MH diagnostic centre from 2002 to 2022 were enrolled. Each proband was a representative of one unrelated family. Probands were investigated according to diagnostic guidelines valid at the time of reporting by molecular genetic testing and muscle in vitro contraction test (IVCT). All probands with completed MH diagnostics were included in the final analysis. Results: By the end of 2022, there were a total of 303 reports related to the risk of MH. A total of 236 IVCT tests were performed, 129 negatives and 107 positives. There were 223 persons susceptible to MH (MHS) registered from 75 Czech and 8 Slovak families. A diagnostic pathogenic variant in the RYR1 gene was found only in 37 MHS families (45%). MH was excluded in 87 families (MHN). Conclusion: In 20 years of systematic work, a unique set of 83 MHS families has been collected in our Czech and Slovak populations. Despite the routine availability of state-of-the-art MH diagnostics, more than half of our MH families do not have a confirmed MH genetic background and can benefit from scientific progress and further research. [ABSTRACT FROM AUTHOR]

Malignant hyperthermia (MH) is a rare but potentially life-threatening emergency characterized by a hypermetabolic state which leads to pyrexia and muscle rigidity. It is a genetic disorder that displays autosomal dominant inheritance. Defects of the RyR1 and CACNA1S genes cause dysregulated calcium release within skeletal myocytes on exposure to triggering agents, causing tetanic contraction of the myocyte. Triggering agents are the halogenated volatile anaesthetic agents and suxamethonium chloride. Diagnosing MH involves genetic testing and an in-vitro contracture test. This is performed at specialist MH centres. An unexplained rise in end-tidal CO 2 and tachycardia should prompt the anaesthetist to consider an MH crisis. This can occur at any time during an anaesthetic or within the ensuing hours. A previous uneventful general anaesthetic does not rule out a crisis happening on subsequent anaesthetics. Crisis management comprises of stopping the offending triggering agent and provision of a clean volatile-free anaesthetic circuit. Activated charcoal filters are useful for the sequestration of halogenated vapours. Dantrolene is the only available treatment and should be immediately available in every area providing anaesthetic assistance. Active body cooling should be implemented to target core body temperatures below 38.5°C. Supportive measures should be instigated until the reaction has subsided. Guidelines produced by the Association of Anaesthetists of Great Britain and Ireland and the European Malignant Hyperpyrexia Group are available to aid in the management of the MH-susceptible patient and an MH crisis. [ABSTRACT FROM AUTHOR]

Ryanodine receptor (RYR) mutations confer stress-triggered malignant hyperthermia (MH) susceptibility. Dietary caffeine (CAF) is the most commonly consumed psychoactive compound by humans. CAF-triggered Ca2+ release and its influences on skeletal muscle contractility are widely used as experimental tools to study RYR function/dysfunction and diagnose MH susceptibility. We hypothesize that dietary CAF achieving blood levels measured in human plasma exacerbates the penetrance of RYR1 MH susceptibility mutations triggered by gaseous anesthetic, affecting both central and peripheral adverse responses. Heterozygous R163C-RYR1 (HET) MH susceptible mice are used to investigate the influences of dietary CAF on both peripheral and central responses before and after induction of halothane (HAL) maintenance anesthesia under experimental conditions that maintain normal core body temperature. HET mice receiving CAF (plasma CAF 893 ng/ml) have significantly shorter times to respiratory arrest compared with wild type, without altering blood chemistry or displaying hyperthermia or muscle rigor. Intraperitoneal bolus dantrolene before HAL prolongs time to respiratory arrest. A pilot electrographic study using subcutaneous electrodes reveals that dietary CAF does not alter baseline electroencephalogram (EEG) total power, but significantly shortens delay to isoelectric EEG, which precedes respiratory and cardiac arrest. CAF ± HAL are studied on RYR1 single-channel currents and HET myotubes to define molecular mechanisms of gene-by-environment synergism. Strong pharmacological synergism between CAF and HAL is demonstrated in both single-channel and myotube preparations. Central and peripheral nervous systems mediate adverse responses to HAL in a HET model of MH susceptibility exposed to dietary CAF, a modifiable lifestyle factor that may mitigate risks of acute and chronic diseases associated with RYR1 mutations. SIGNIFICANCE STATEMENT: Dietary caffeine at a human-relevant dose synergizes adverse peripheral and central responses to anesthesia in malignant hyperthermia susceptible mice. Synergism of these drugs can be attributed to their actions at ryanodine receptors.

Malignant hyperthermia (MH) is a rare and life-threatening pharmacogenetic disorder triggered by volatile anesthetics, the depolarizing muscle relaxant succinylcholine, and rarely by strenuous exercise or environmental heat. The exact prevalence of MH is unknown, and it varies from 1:16 000 in Denmark to 1:100 000 in New York State. The underlying mechanism of MH is excessive calcium release from the sarcoplasmic reticulum (SR), leading to uncontrolled skeletal muscle hyper-metabolism. Genetic mutations in ryanodine receptor type 1 ( RYR1) and CACNA1S have been identified in approximately 50% to 86% and 1% of MH-susceptible (MHS) individuals, respectively. Classic clinical symptoms of MH include hypercarbia, sinus tachycardia, masseter spasm, hyperthermia, acidosis, muscle rigidity, hyperkalemia, myoglobinuria, and etc. There are two types of testing for MH: a genetic test and a contracture test. Contracture testing is still being considered as the gold standard for MH diagnosis. Dantrolene is the only available drug approved for the treatment of MH through suppressing the calcium release from SR. Since clinical symptoms of MH are highly variable, it can be difficult to establish a diagnosis of MH. Nevertheless, prompt diagnosis and treatments are crucial to avoid a fatal outcome. Therefore, it is very important for anesthesiologists to raise awareness and understand the characteristics of MH. This review summarizes epidemiology, clinical symptoms, diagnosis and treatments of MH and any new developments.

Lingcan Tan,1 Hong Yu,1 Junyu Yan,2 Chunyuan Liu,3 Kun Xiao,4 Jin Yin,5 Yunxia Zuo,1 Tao Zhu,1 Xiaoqian Deng1 1Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, 610041, People’s Republic of China; 2Department of Anesthesiology, Karamay Hospital of Integrated Traditional Chinese and Western Medicine, Karamay, People’s Republic of China; 3Department of Anesthesiology, Chongqing Liangping District People’s Hospital, Chongqing, 405200, People’s Republic of China; 4School of Information and Software Engineering, University of Electronic Science and Technology of China, Chengdu, 610054, People’s Republic of China; 5West China Biomedical Big Data Center, West China Hospital, Sichuan University, Chengdu, 610041, People’s Republic of ChinaCorrespondence: Xiaoqian Deng, Department of Anesthesiology, West China Hospital, Sichuan University, No. 37 Guoxue Alley, Chengdu, 610041, People’s Republic of China, Email d_xiaoqian@163.comPurpose: The National Remote Emergency System for Malignant Hyperthermia (MH-NRES) is an applet in China, designed to help anesthesiologists manage MH crisis. However, there is limited information about encountered difficulties in dealing with MH among Chinese anesthesiologists. The purpose of the study was to explore the current competency and encountered difficulties in the management of MH, as a key first step for assessing the potential user needs to develop the MH-NRES.Methods: The hospitals of different levels in different provinces across China were invited to participate in an online survey from November to December 2021. Anesthesiologists completed the online questionnaire containing four sections including demographic information, knowledge, competency, and continuing education about MH.Results: A total of 1357 valid questionnaires were completed from anesthesiologists, most respondents (66.7%, n = 905) correctly answered the MH trigger drugs included volatile anesthetics and succinylcholine. However, most respondents (77.0%, n = 1045) did not know that the recommended initial dose of domestic dantrolene. Up to 83.9% (n = 1138) stated that their hospitals did not store dantrolene for MH emergency. More than half of respondents thought that it would take more than one hour to obtain dantrolene in emergency. Less work experiences, lower levels of hospital and educations and professional titles were associated with lower competency scores in managing MH. Only 31.0% (n = 936) reported that their hospital had ever conducted MH continuing education curricula. Scenario simulation is the training method that most interests the participants (79.0%, n = 1072) but a whopping 46.9% (n = 637) never received simulation.Conclusion: The study indicated that difficulty in obtaining dantrolene, lack of competency in management of MH, difficulty in obtaining professional help, and poor teamwork were the main problems of most anesthesiologists in face of MH.Keywords: malignant hyperthermia, questionnaire, competency, dantrolene, education

Systemic delivery of antisense oligonucleotides (AO) for DMD exon skipping has proven effective for reframing DMD mRNA, rescuing dystrophin expression, and slowing disease progression in animal models. In humans with Duchenne muscular dystrophy treated with AOs, low levels of dystrophin have been induced, and modest slowing of disease progression has been observed, highlighting the need for improved efficiency of human skipping drugs. Here, we demonstrate that dantrolene and Rycals S107 and ARM210 potentiate AO-mediated exon skipping of exon 44 or exon 45 in patient-derived myotube cultures with appropriate mutations. Further, dantrolene is shown to boost AO-mediated exon skipping in patient-derived, induced cardiomyocyte cultures. Our findings further validate the ryanodine receptors (RyR) as the likely target responsible for exon skip boosting and demonstrate potential applicability beyond exon 51 skipping. These data provide preclinical support of dantrolene trial as an adjuvant to AO-mediated exon-skipping therapy in humans and identify a novel Rycal, ARM210, for development as a potential exon-skipping booster. Further, they highlight the value of mutation-specific DMD culture models for basic discovery, preclinical drug screening and translation of personalized genetic medicines.

Lingcan Tan,1,&ast; Yi Teng,1,&ast; Hong Yu,1 Chunyuan Liu,2 Kun Xiao,3 Jin Yin,4 Yunxia Zuo,1 Tao Zhu,1 Xiaoqian Deng1 1Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, 610041, People’s Republic of China; 2Department of Anesthesiology, Chongqing Liangping District People’s Hospital, Chongqing, 405200, People’s Republic of China; 3School of Information and Software Engineering, University of Electronic Science and Technology of China, Chengdu, 610054, People’s Republic of China; 4West China Biomedical Big Data Center, West China Hospital, Sichuan University, Chengdu, 610041, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Xiaoqian Deng, Department of Anesthesiology, West China Hospital, Sichuan University, No. 37 Guoxue Alley, Chengdu, 610041, People’s Republic of China, Tel +86 885423592, Email d_xiaoqian@163.comPurpose: Malignant hyperthermia (MH) is a rare but fatal pharmacogenetic disorder, triggered by inhalational anesthetics or succinylcholine. Since the first nonprofit academic organization China Malignant Hyperthermia Emergency Assistance WeChat-based Group (CMHEA Group) was established in 2015, they have actively participated in the diagnosis and treatment of MH patients. Based on the CMHEA Group, the aim of the study was to retrospectively analyze the characteristics of suspected MH in China from 2015 to 2020.Methods: We conducted a retrospective analysis of the suspected MH patients from 2015 to 2020, for analyzing the current clinical diagnosis, treatment and prognosis of MH in China.Results: A total of 58 suspected MH cases occurred from 2015 to 2020, of these, 36 cases were collected with detailed data. The MH clinical grading score of 36 patients ranged from 33 to 73, with a median of 55. Abnormal hyperthermia and hypercarbia were the most common early signs of MH. Four patients were confirmed carrying six different potential MH-causative mutations. Of the total 58 cases, 14 patients (24.1%) received dantrolene and the whole mortality rate was 53.4%. Compared to the patients not receiving dantrolene treatment, the survival rate of patients receiving dantrolene treatment was significantly higher than that of patients not receiving dantrolene (78.6% vs 36.4%, p = 0.007).Conclusion: The current main diagnostic methods of suspected MH in China are still clinical diagnosis. Hence, it is critical to keep dantrolene for immediate accessibility with the introduction of domestic dantrolene to China. The WeChat group model has played an important but limited role in quick diagnosis and treatment of MH.Keywords: malignant hyperthermia, dantrolene, mortality, China

Abstract Background Intravenous dantrolene is often prescribed for hypermetabolic syndromes other than the approved indication of malignant hyperthermia (MH). To clarify the extent of and indications for dantrolene use in conditions other than MH, we sought to document current practices in the frequency, diagnoses, clinical characteristics and outcomes associated with dantrolene treatment in critical care settings. Methods Inpatients receiving intravenous dantrolene from October 1, 2004 to September 30, 2014 were identified retrospectively in the U.S. Veterans Health Administration national database. Extracted data included; diagnoses of hypermetabolic syndromes; triggering drugs; dantrolene dosages; demographics; vital signs; laboratory values; in-hospital mortality; complications; and lengths of stay. Frequency and mortality of patients who did not receive dantrolene were obtained in selected diagnoses for exploratory comparisons. Results Dantrolene was administered to 304 inpatients. The most frequent diagnoses associated with dantrolene treatment were neuroleptic malignant syndrome (NMS; N = 108, 35.53%) and sepsis (N = 47, 15.46%), with MH accounting for only 13 (4.28%) cases. Over half the patients had psychiatric comorbidities and received psychotropic drugs before dantrolene treatment. Common clinical findings in patients receiving dantrolene included elevated temperature (mean ± SD; 38.7 ± 1.3 °C), pulse (116.33 ± 22.80/bpm), respirations (27.75 ± 9.58/min), creatine kinase levels (2,859.37 ± 6,646.88 IU/L) and low pO2 (74.93 ± 40.16 mmHg). Respiratory, renal or cardiac failure were common complications. Mortality rates in-hospital were 24.01% overall, 7.69% in MH, 20.37% in NMS and 42.55% in sepsis, compared with mortality rates in larger and possibly less severe groups of unmatched patients with MH (5.26%), NMS (6.66%), or sepsis (41.91%) who did not receive dantrolene. Conclusions In over 95% of cases, dantrolene administration was associated with diagnoses other than MH in critically-ill patients with hypermetabolic symptoms and medical and psychiatric comorbidities. Exploratory survey data suggested that the efficacy and safety of dantrolene in preventing mortality in hypermetabolic syndromes other than MH remain uncertain. However, randomized and controlled studies using standardized criteria between groups matched for severity are essential to guide practice in using dantrolene.

Rationale: Hyperthermia induced by psychomotor stimulants may cause leakage of the blood-brain barrier, vasogenic edema, and lethality in extreme cases. Current treatments such as whole-body cooling are only symptomatic and a clear need to develop pharmacological interventions exists. Dantrolene sodium, a peripheral muscle relaxant used in the treatment of malignant hyperthermia, has been proposed as potentially effective to treat MDMA-hyperthermia in emergency rooms. However, debate around its efficacy for this indication persists. Objectives: To investigate dantrolene as a treatment for illicit hyperthermia induced by psychomotor stimulant drugs, we examined how Ryanodex®, a concentrated formulation of dantrolene sodium produced by Eagle Pharmaceuticals, influences 3,4-methylenedioxymethamphetamine (MDMA)- and methamphetamine (METH)-induced hyperthermia in awake freely moving rats. We injected rats with moderate doses of MDMA (9 mg/kg) and METH (9 mg/kg) and administered Ryanodex® intravenously (6 mg/kg) after the development of robust hyperthermia (>2.5 °C) mimicking clinical acute intoxication. We conducted simultaneous temperature recordings in the brain, temporal muscle, and skin to determine the basic mechanisms underlying temperature responses. To assess the efficacy of dantrolene in attenuating severe hyperthermia, we administered MDMA to rats maintained in a warm ambient environment (29 °C), conditions which produce robust brain and body hyperthermia (>40 °C) and lethality. Results: Dantrolene failed to attenuate MDMA- and METH-induced hyperthermia, though locomotor activity was significantly reduced. All animals maintained at warm ambient temperatures that received dantrolene during severe drug-induced hyperthermia died within or soon after the recording session. Conclusions: Our results suggest that dantrolene sodium formulations are not mechanistically suited to treat MDMA- and METH-induced hyperthermia. [ABSTRACT FROM AUTHOR]

Dantrolene is an intra-cellularly acting skeletal muscle relaxant used for the treatment of the rare genetic disorder, malignant hyperthermia (MH). In most cases, MH susceptibility is caused by dysfunction of the skeletal ryanodine receptor (RyR1) harboring one of nearly 230 single-point MH mutations. The therapeutic effect of dantrolene is the result of a direct inhibitory action on the RyR1 channel, thus suppressing aberrant Ca2+ release from the sarcoplasmic reticulum. Despite the almost identical dantrolene-binding sequence exits in all three mammalian RyR isoforms, dantrolene appears to be an isoform-selective inhibitor. Whereas RyR1 and RyR3 channels are competent to bind dantrolene, the RyR2 channel, predominantly expressed in the heart, is unresponsive. However, a large body of evidence suggests that the RyR2 channel becomes sensitive to dantrolene-mediated inhibition under certain pathological conditions. Although a consistent picture of the dantrolene effect emerges from in vivo studies, in vitro results are often contradictory. Hence, our goal in this perspective is to provide the best possible clues to the molecular mechanism of dantrolene's action on RyR isoforms by identifying and discussing potential sources of conflicting results, mainly coming from cell-free experiments. Moreover, we propose that, specifically in the case of the RyR2 channel, its phosphorylation could be implicated in acquiring the channel responsiveness to dantrolene inhibition, interpreting functional findings in the structural context. [ABSTRACT FROM AUTHOR]

Impaired consciousness is a frequent phenomenon after general anesthesia. In addition to the classical causes (e.g., overhang of sedatives), an impairment of consciousness can also be an adverse side effect of drugs. Many drugs used in anesthesia can trigger these symptoms. Alkaloids, such as atropine can trigger a central anticholinergic syndrome, opioids can promote the occurrence of serotonin syndrome and the administration of a neuroleptic can lead to neuroleptic malignant syndrome. These three syndromes are difficult to diagnose due to the individually very heterogeneous symptoms. Mutual symptoms, such as impaired consciousness, tachycardia, hypertension and fever further complicate the differentiation between the syndromes; however, more individual symptoms, such as sweating, muscle tension or bowl sounds can be helpful in distinguishing these syndromes. The time from the trigger event can also help to differentiate the syndromes. The central anticholinergic syndrome is the fastest to appear, usually taking just a few of hours from trigger to clinical signs, serotonin syndrome takes several hours up to 1 day to show and neuroleptic malignant syndrome usually takes days. The clinical symptoms can range from mild to life-threatening. Generally, mild cases are treated with discontinuation of the trigger and extended observation. More severe cases can require specific antidotes. The specific treatment recommended for central anticholinergic syndrome is physostigmine with an initial dose of 2 mg (0.04 mg/kg body weight, BW) administered over 5 min. For serotonin syndrome an initial dose of 12 mg cyproheptadine followed by 2 mg every 2 h is recommended (maximum 32 mg/day or 0.5 mg/kgBW day−1) but this medication is only available in Germany as an oral formulation. For neuroleptic malignant syndrome 25–120 mg dantrolene (1–2.5 mg/kgBW maximum 10 mg/kgBW day−1) is the recommended treatment. [ABSTRACT FROM AUTHOR]

Purpose. Malignant hyperthermia (MH) is a rare genetic disorder but one of the most severe complications of general anesthesia. The mortality rate of MH has dropped from 70% in the 1960s to 15% because of dantrolene, the only currently accepted specific treatment for MH. In this study, we retrospectively identified the optimal dantrolene administration conditions to reduce MH mortality further. Methods. Our database performed a retrospective analysis of patients with MH clinical grading scale (CGS) grade 5 (very likely) or 6 (almost certain) between 1995 and 2020. We examined whether dantrolene administration affected mortality and compared the clinical variables associated with improved prognosis. Furthermore, a multivariable logistic regression analysis was used to identify specific variables associated with improved prognosis. Results. 128 patients met the inclusion criteria. 115 patients were administered dantrolene; 104 survived, and 11 died. The mortality rate of patients who were not administered dantrolene was 30.8%, which was significantly higher than those of patients who were administered dantrolene (P = 0.047). Among patients administered dantrolene, the interval from the first sign of MH to the start of dantrolene administration was significantly longer in the deceased than in the survivors (100 min vs. 45.0 min, P < 0.001), and the temperature at the start of dantrolene administration was also significantly higher in the deceased (41.6°C vs. 39.1°C, P < 0.001). There was no significant difference in the rate of increase in temperature between the two, but there was a substantial difference in the maximum temperature (P < 0.001). The multivariable analysis also showed that the patient's temperature at dantrolene administration and interval from the first MH sign to dantrolene administration was significantly associated with improved prognosis. Conclusions. Dantrolene should be given as rapidly as possible once MH has been diagnosed. Beginning treatment at a more normal body temperature can prevent critical elevations associated with a worse prognosis. [ABSTRACT FROM AUTHOR]