Unraveling the molecular dynamics of sugammadex-rocuronium complexation: A blueprint for cyclodextrin drug design.

Sugammadex, marketed as Bridion™, is an approved cyclodextrin (CD) based drug for the reversal of neuromuscular blockade in adults undergoing surgery. Sugammadex forms an inclusion complex with the neuromuscular blocking agent (NMBA) rocuronium, allowing rapid reversal of muscle paralysis. In silico methods have been developed for studying CD inclusion complexes, aimed at accurately predicting their structural, energetic, dynamic, and kinetic properties, as well as binding constants. Here, a computational study aimed at characterizing the sugammadex-rocuronium system from the perspective of docking calculations, free molecular dynamics (MD) simulations, and biased metadynamics simulations with potential of mean force (PMF) calculations is presented. The aim is to provide detailed information about this system, as well as to use it as a model system for validation of the methods. This method predicts results in line with experimental evidence for both the optimal structure and the quantitative value for the binding constant. Interestingly, there is a less profound preference for the orientation than might be assumed based on electrostatic interactions, suggesting that both orientations may exist in solution. These results show that this technology can efficiently analyze CD inclusion complexes and could be used to facilitate the development and optimization of novel applications for CDs.

Insights into the spectrofluorometric determination of the neuromuscular blocker mivacurium chloride.

Fluorescence spectroscopy is gaining interest in the analysis and quantitative determination of different drugs. This study was carried out to investigate the fluorometric properties of the short-acting muscle relaxant mivacurium in its pure form, injection, and human plasma. It is nondepolarizing skeletal muscle relaxant for intravenous (IV) administration. Mivacurium shows a strong native fluorescence in methanol at 317 nm after excitation at 230 nm (Method I). The critical parameters that may influence the fluorescence of this drug were carefully studied. A linear response between concentration and fluorescence was constructed over the concentration range: 20.0 to 400.0 ng/mL with determination coefficient (r2) equal to 0.9998. Additionally, the correlation coefficient of the linear relationship (r) was found to be 0.9999 with a slope = 2.196 and intercept = -16.61. Limits of quantitation and detection were calculated mathematically to be 17.45 and 5.75 ng/mL respectively. Further estimation of mivacurium in spiked human plasma was performed by construction of specific calibration curve and the obtained correlation coefficient was 0.9948. Moreover, the ability to determine mivacurium in the presence of commonly co-administered drugs were investigated including propofol and thiopental. Method II includes the determination of MVC in the presence of propofol utilizing the first derivative synchronous fluorescence spectroscopy. The results of method II indicated acceptable percentage recoveries from 98.88 to 100.75 %. Statistical evaluation of the results revealed satisfactory accuracy and precision.

Rapid detection of rocuronium based on host/guest complex between a pyrene derivative and sugammadex.

Rocuronium is widely used in surgery as a neuromuscular relaxant, but it has been difficult to accurately control its specific dosage in clinical operation. Therefore, the development of fast and instant rocuronium detection methods has important application value for reducing risks and safeguarding health. In this study, N, N, N-trimethyl-4-(pyrene-1-butyl)-ammonium bromide (PyBTA) was designed as a probe to detect rocuronium rapidly. The method relied on replacing PyBTA in sugammadex with rocuronium to induce changes in fluorescence intensity of PyBTA, thereby realizing quantitative detection. Its sensing performance and detection mechanism were explored systematically by spectroscopy. The linear range of this method was 0.5-10 µM and the detection limit of it was 0.3 µM. In addition, we confirmed that the host-guest interaction among PyBTA, sugammadex, and rocuronium was mainly driven by electrostatic and hydrophobic interactions.

The effect of various dilute administration of rocuronium bromide on both vascular pain and pharmacologic onset: a randomized controlled trial.

BACKGROUND: Rocuronium bromide (RB) is known to cause vascular pain. Although there have been a few reports that diluted administration causes less vascular pain, there have been no studies investigating diluted administration and the onset time of muscle relaxation. Therefore, we examined the influence of diluted administration of RB on the onset time of muscle relaxation and vascular pain. METHODS: 39 patients were randomly assigned to three groups: RB stock solution 10 mg/ml (Group 1), two-fold dilution 5 mg/ml (Group 2), or three-fold dilution 3.3 mg/ml (Group 3). After the largest vein of the forearm was secured, anesthesia was induced by propofol and 0.6 mg/kg of RB was administered. The evaluation method devised by Shevchenko et al. was used to evaluate the degree of vascular pain. The time from RB administration until the maximum blocking of T1 by TOF stimulation was measured. RESULTS: There was no significant difference in escape behaviors of vascular pain among the three groups, and the onset time of muscle relaxation was significantly slower in Group 3 than in Group 1 (p = 0.033). CONCLUSION: Our results suggested that it is unnecessary to dilute RB before administration if a large vein in the forearm is used. TRIAL REGISTRATION: UMINCTR Registration number UMIN000026737 . Registered 29 Mar 2017.

Screen printed potentiometric sensor for therapeutic monitoring of rocuronium at the point of care.

Rocuronium bromide (ROC) is currently regarded as the 'gold-standard' in emergency medicine and anesthesia. Globally, millions of human beings are daily administered ROC at emergency settings where it is favored among all the neuromuscular blockers, particularly succinylcholine, for both its fast onset of action and short duration. However, it has been reported that 45% of patients in the post-anesthesia care unit are susceptible to residual postoperative paralysis, undesired ventilator effects and incomplete recovery after ROC administration. From an analytical chemistry perspective, direct determination of ROC is a difficult approach due to the complexity in isolation from biological specimens as well as the lack of a sensitive detection techniques and detectable chromophore. This contribution describes the development of a calix[6]arene-based screen-printed electrode (SPE) that is capable of ROC detection in biological samples at the point of care. This fabricated SPE (sensor 1) exhibited superior performance characteristics (slope, LOD and life time) with respect to an ionophore-free liquid-contact electrode, LCE, (sensor 2). The proposed SPE showed a linear response over a concentration from 1 µM to 10 mM, with a Nernstian slope of 57.9 mV/decade and a detection limit of 0.39 µM. Moreover, this sensor showed a considerable selectivity towards ROC in presence of the anticipated interfering ions. To investigate the ability of the SPE to detect ROC in real biological specimens, ROC has been spiked at a concentration comparable to its anticipated level in human plasma (Cmax~ 40 µM) and the proposed SPE displayed an excellent platform for therapeutic drug monitoring (TDM) of ROC with respect to UV-spectrophotometry and LC/MS. Finally, the developed SPE was used for the determination of ROC in its commercial pharmaceutical formulation.

Dexamethasone Does Not Inhibit Sugammadex Reversal After Rocuronium-Induced Neuromuscular Block.

BACKGROUND: Sugammadex is a relatively new molecule that reverses neuromuscular block induced by rocuronium. The particular structure of sugammadex traps the cyclopentanoperhydrophenanthrene ring of rocuronium in its hydrophobic cavity. Dexamethasone shares the same steroidal structure with rocuronium. Studies in vitro have demonstrated that dexamethasone interacts with sugammadex, reducing its efficacy. In this study, we investigated the clinical relevance of this interaction and its influence on neuromuscular reversal. METHODS: In this retrospective case-control study, we analyzed data from 45 patients divided into 3 groups: dexamethasone after induction group (15 patients) treated with 8 mg dexamethasone as an antiemetic drug shortly after induction of anesthesia; dexamethasone before reversal group (15 patients) treated with dexamethasone just before sugammadex injection; and control group (15 patients) treated with 8 mg ondansetron. All groups received 0.6 mg/kg rocuronium at induction, 0.15 mg/kg rocuronium at train-of-four ratio (TOF) 2 for neuromuscular relaxation, and 2 mg/kg sugammadex for reversal at the end of the procedure at TOF2. Neuromuscular relaxation was monitored with a TOF-Watch® system. RESULTS: The control group had a recovery time of 154 ± 54 seconds (mean ± SD), the dexamethasone after induction group 134 ± 55 seconds, and the dexamethasone before reversal group 131 ± 68 seconds. The differences among groups were not statistically significant (P = 0.5141). CONCLUSIONS: Our results show that the use of dexamethasone as an antiemetic drug for the prevention of postoperative nausea and vomiting does not interfere with reversal of neuromuscular blockade with sugammadex in patients undergoing elective surgery with general anesthesia in contrast to in vitro studies that support this hypothesis.

[Curare-Like Camphor Derivatives and Their Biological Activity].

The synthesis and evaluation of muscle relaxant activity of series of dimeric camphor derivatives are described. Compounds in which the quaternary nitrogen atoms are separated by aromatic chain exhibited the highest efficiency as muscle relaxant. It was shown the screening of a charged atom and counter-ion does not have a significant role on the activity of the studied agents.

Structural characterization of a degradation product of rocuronium using nanoelectrospray-high resolution mass spectrometry.

Rocuronium bromide is a non-depolarizing neuromuscular blocking agent that causes rapid muscle relaxation after intravenous injection. Regulatory authorities for registration of pharmaceuticals for human use require the evaluation of the stability of active compounds under various stress conditions. Forced degradation of rocuronium bromide was performed under hydrolytic, thermal, photolytic, and oxidative settings. HPLC-UV/vis analysis revealed an unknown degradation product under oxidative conditions (1% H2 O2 , reflux for 1 h). Investigation of the respective HPLC fraction by high resolution mass spectrometry indicated a formal loss of CH2 and an addition of one oxygen atom to the intact drug molecule. Additional multistage mass spectrometric structural elucidation experiments aided by complementary information from analysis of the intact drug and known rocuronium-related compounds showed that the morpholine moiety was unstable under oxidative stress. The data demonstrated that the morpholine ring was opened and transformed to an N-ethanoyl-formamide group. The structure was supported by appropriate mechanistic explanations.

[Physicochemical stability study of injectable solutions of cisatracurium besilate in clinical conditions]. / Stabilité physico-chimique des solutions injectables de bésilate de cisatracurium dans les conditions cliniques d'utilisation.

OBJECTIVES: To assess the stability of cisatracurium besilate solution stored at 5°C and 25°C. MATERIALS AND METHODS: Cisatracurium solutions at 2, 5 and 0.1mg/mL in 0.9 % sodium chloride or 5 % glucose were exposed to 5°C and 25°C under 60 % relative humidity for seven days. The physicochemical stability was assessed at 24, 48hours and seven days with dosage of the active substance, detection of degradation products and a possible racemization, measuring pH, osmolality and turbidity, assessment of coloration, visible particles and invisible particles count. RESULTS: Cisatracurium besilate present good stability for 24hours at 5°C and 25°C for concentrations between 0.1 and 5mg/mL. Beyond 24hours, the solutions at 2 and 5mg/mL remained stable for seven days at 5°C. At 25°C, potentially toxic degradation products appear in solutions of 0.1mg/mL between 24 and 48hours. No racemization was detected, the drug remains in its active form cis. CONCLUSION: Cisatracurium solutions at 2 and 5mg/mL may be stored at 5°C or 25°C for seven days. It's advisable to keep the solutions in a dilution of 0.1mg/mL in 0.9 % sodium chloride or 5 % glucose in the refrigerator. No diluted solution should be stored at room temperature beyond 24hours.

[Possible clinical potential in reverting muscular block with sugammadex in anaesthesia and surgery]. / Muligt klinisk potentiale ved revertering af neuromuskulær blokade med sugammadex ved anæstesi og kirurgi.

Neuromuscular blockers (NMBs) provide good conditions for endotracheal intubation and surgery. NMBs have been associated with higher morbidity and mortality, mainly due to post-operative residual neuromuscular block. This may become history with the advent of sugammadex - an antidote to the NMB rocuronium - which within 1-3 minutes neutralizes the effects of rocuronium. High-dose rocuronium is now an alternative to suxamethonium in acute or short procedures and in a situation, where ventilation/intubating cannot be performed, sugammadex can reverse the rocuronium blockade within minutes.

[Storage at room temperature does not change cisatracurium onset time: a prospective, randomized, double-blind controlled study]. / La température de conservation du cisatracurium ne modifie pas le délai d'action: étude randomisée, en double insu

OBJECTIVE: Storage of cisatracurium at room temperature seems to have no effect on its degradation in vitro contrary to the recommendations of storage at +4°C. The purpose of this study was to evaluate the influence of cisatracurium' s storage temperature on its onset time. STUDY DESIGN: Prospective, randomized, double-blind trial study. PATIENTS AND METHODS: Thirty patients were enrolled. The control group consisted of 15 patients receiving cisatracurium (0.15mg/kg) stored at room temperature and the intervention consisted of 15 patients receiving cisatracurium (0.15mg/kg) stored at +4°C. The primary endpoint was to compare cisatracurium onset time depending on the storage temperature. RESULTS: Cisatracurium onset time was 235 (180-292) seconds in the "room temperature" group vs. 240 (210-292) seconds in the "refrigerated" group. There was no difference between the onset of cisatracurium depending on the temperature of storage (p=0.51). Subgroups analysis in the "room temperature" group did not show any difference in cisatracurium onset depending on whether it was stored at room temperature for one, two or three weeks. Excellent intubation score was obtained for 100% of the patients. CONCLUSION: This study demonstrated that cisatracurium's storage at room temperature had no influence on its onset time. It provides an argument for the preservation of cisatracurium at room temperature for a period not exceeding 21 days. Monitoring the onset of curarization may increase the quality score of intubation.

The cyclodextrin sugammadex and anaphylaxis to rocuronium: is rocuronium still potentially allergenic in the inclusion complex form?

Rocuronium, a non-depolarizing neuromuscular blocking drug has a rapid onset of action, a comparatively low potency and, with a more favourable side effects profile than succinylcholine, it has become a popular alternative to that drug for rapid sequence inductions in anaesthesia. The rocuronium-binding cyclodextrin derivative sugammadex, prepared by per-6 substitution of the primary hydroxyls of γ-cyclodextrin with thiol ether-linked propionic acid side chains to extend the hydrophobic cavity to accommodate rocuronium, is used to reverse neuromuscular blockade by encapsulating the drug as an inclusion complex and removing it from the neuromuscular junction to the plasma. It has recently been suggested that sugammadex might also be of value in the management of rocuronium-induced anaphylaxis and this has been potentially supported by recent case reports. However, before sugammadex can be recommended for this purpose, it is important to establish whether or not the allergenic substituted ammonium groups at each end of the rocuronium molecule in the inclusion complex are masked within the cavity or left exposed for interaction with rocuronium-reactive IgE antibodies in the sera of rocuronium-allergic patients. Detailed experimental strategies and experimental protocols to investigate the allergenic potential of the sugammadex-rocuronium inclusion complex are presented and a possible explanation of the apparently rapid and successful reversal of anaphylaxis by administration of sugammadex is advanced and discussed.

Drug-specific cyclodextrins with emphasis on sugammadex, the neuromuscular blocker rocuronium and perioperative anaphylaxis: implications for drug allergy.

Cyclodextrins, oligosaccharides linked in a circular arrangement around a central cavity, are used extensively in the pharmaceutical industry to improve drug delivery. Their usefulness depends on their capacity to form a drug inclusion, or host-guest, complex within the cavity. In an attempt to improve the delivery of the widely used neuromuscular blocking drug (NMBD) rocuronium, a rocuronium inclusion complex was formed with a chemically modified γ-cyclodextrin. The high binding affinity and specificity of the modified carrier (named sugammadex) for rocuronium (and other aminosteroid NMBDs) led to its use in anaesthesia as an innovative and useful agent for rapid reversal of rocuronium-induced neuromuscular block by sequestering the drug as an inclusion complex. This, in turn, led to the suggestion that sugammadex might be useful to remove the NMBD from the circulation of patients experiencing rocuronium-induced anaphylaxis, a suggestion subsequently supported in case reports where traditional treatment had failed. Successful resuscitations suggested that sugammadex might be a valuable new treatment for such intractable cases but, given the inappropriateness of clinical trials, confirmation or refutation will have to await the slow accumulation of results of individual case reports. Important questions related to antibody accessibility of drug allergenic structures on the rocuronium-sugammadex inclusion complex, and the competition between sugammadex and IgE antibodies (both free and cell bound) for rocuronium, also remain and can be investigated in vitro. The sugammadex findings indicate that the use of carrier molecules such as the cyclodextrins to improve drug delivery will sometimes give rise to changed immunologic and allergenic behaviour of some drugs and this will have to be taken into account in preclinical drug safety assessments of drug-carrier complexes. The possibility of encapsulating and removing other allergenic drugs, e.g., penicillins and cephalosporins, in cases of difficult-to-reverse anaphylaxis to these drugs is discussed.

A structural and mutagenic blueprint for molecular recognition of strychnine and d-tubocurarine by different cys-loop receptors.

Cys-loop receptors (CLR) are pentameric ligand-gated ion channels that mediate fast excitatory or inhibitory transmission in the nervous system. Strychnine and d-tubocurarine (d-TC) are neurotoxins that have been highly instrumental in decades of research on glycine receptors (GlyR) and nicotinic acetylcholine receptors (nAChR), respectively. In this study we addressed the question how the molecular recognition of strychnine and d-TC occurs with high affinity and yet low specificity towards diverse CLR family members. X-ray crystal structures of the complexes with AChBP, a well-described structural homolog of the extracellular domain of the nAChRs, revealed that strychnine and d-TC adopt multiple occupancies and different ligand orientations, stabilizing the homopentameric protein in an asymmetric state. This introduces a new level of structural diversity in CLRs. Unlike protein and peptide neurotoxins, strychnine and d-TC form a limited number of contacts in the binding pocket of AChBP, offering an explanation for their low selectivity. Based on the ligand interactions observed in strychnine- and d-TC-AChBP complexes we performed alanine-scanning mutagenesis in the binding pocket of the human α1 GlyR and α7 nAChR and showed the functional relevance of these residues in conferring high potency of strychnine and d-TC, respectively. Our results demonstrate that a limited number of ligand interactions in the binding pocket together with an energetic stabilization of the extracellular domain are key to the poor selective recognition of strychnine and d-TC by CLRs as diverse as the GlyR, nAChR, and 5-HT(3)R.

Diquaternized curarelike myorelaxants: structure and biological activity.

This review discusses the most active natural and synthetic curarelike compounds demonstrating myorelaxants activity. The data are grouped according to chemical structures, namely, quinoline and isoquinoline myorelaxants, myorelaxants with saturated heterocyclic or alkylamine fragments, myorelaxants with a steroid framework, natural and synthetic alkaloid myorelaxants.

Aconitum and Delphinium alkaloids of curare-like activity. QSAR analysis and molecular docking of alkaloids into AChBP.

Early studies have shown that some of diterpenoid alkaloids, found in highly toxic plants of the genera Aconitum and Delphinium, act at neuronal nicotinic acetylcholine receptors (nAChRs) and exhibit potent N-cholinolytic activity. In the current study, GA-MLRA and GA-PLS approaches have been used to build QSAR models to predict N-cholinolytic activity measured in vivo (blockade of neuromuscular conductivity, BNMC and third eyelid relaxing activity, TYRA) and in vitro (suppression of frog's abdominal straight muscles on acetylcholine, SAM) for a series of diterpenoid alkaloids. Random splitting of a data set (five trials in total) produced QSAR models of a good level of correlation between experimental in vitro/in vivo and calculated N-cholinolytic activity expressed as log(1/ED(50)) with following average statistical parameters: log BNMC (r(2) = 0.87, s = 0.14, q(2) = 0.82), log TYRA (r(2) = 0.80, s = 0.29, q(2) = 0.67), log SAM (r(2) = 0.84, s = 29, q(2) = 0.64). QSAR results suggest descriptors accounting for H-bond capability of molecules influence all three type of N-cholinolytic activity with additional contribution of steric and reactivity features as identified for TYRA and SAM data, respectively. The alkaloid-receptor complexes were further analyzed by means of AutoDock Vina docking program using the binding site of MLA complexed with AChBP (homolog of the ligand binding domain of nAChRs) as template. All compounds were shown to be well fitted in the binding pocket of native MLA with good correlation exhibited between their ED(50) and AutoDock Vina binding free energy. An analysis of the possible factors significant for the ligand recognition has been enhanced by comparative docking studies performed for structurally related lycoctonine-type alkaloids (lappaconitine and aconitine) that are known to bind to voltage-gated Na(+) channel, but not to nAChRs.

[Indications and clinical use of sugammadex]. / Indications et utilisation clinique du sugammadex.

Sugammadex, a cyclodextrin, is a novel agent designed to encapsulate selectively steroidal neuromuscular blocking agents such as rocuronium and vecuronium as well. One molecule of sugammadex is able to encapsulate only one molecule of muscle relaxant. This original pharmacological property allows a very rapid reversal of muscle paralysis. After sugammadex injection, a train of four ratio higher than 0.9 is obtained in less than 5 minutes in all the patients whatever the degree of muscle paralysis at the time of reversal and even when anesthesia is maintained with halogenated agents. However, in order to preserve this efficacy, the dose of sugammadex needs to be adjusted to the degree of muscle paralysis at the time of reversal : 2 mg/kg after obtaining 2 responses at the adductor pollicis muscle after a train of four stimulation, 4 mg/kg with a post-tetanic count between 1 and 3 responses, and 12 to 16 mg/kg in case of rescue reversal (3 to 15 minutes after 0.6 to 1.2 mg/kg rocuronium). Even if the original property of sugammadex lets us think that per-operative neuromuscular transmission monitoring would not be furthermore useful, the assessment of the exact degree of muscle paralysis before reversal is mandatory for choosing the right dose of sugammadex.

[Pharmacology of sugammadex]. / Pharmacologie du sugammadex.

Sugammadex is a new molecule derived from a known pharmacological class : the cyclodextrins known and used in human for many years. It was recently demonstrated that cyclodextrins could encapsulate and bind strongly steroidal neuromuscular blocking agents. Among cyclodextrins gamma-cyclodextrins proved to be more efficient. The binding of cyclodextrins to rocuronium and compound's water solubility was greatly improved by addition of 8 side chains to glycopyranoses units and the presence of a negative charge to the end of these side-chains. Animal studies have clearly demonstrated that sugammadex is faster in onset than anticholinesterase agents and is specific of steroidal neuromuscular blocking agents. It cannot reverse neuromuscular block induced by succinylcholine or benzylisoquinolines such as atracurium or cisatracurium. In human, the dose of sugammadex required to reverse shallow block is 2 mg/kg approximately whereas 4 mg/kg is needed to reverse deep level of neuromuscular block with a few responses at the post tetanic count at the adductor pollicis. The use of sugammadex was not associated with recurrence of block when an adequate dose was administered.

[Sugammadex: something new to improve patient safety or simply a gadget?]. / Le sugammadex : une nouveauté qui s'inscrit dans le cadre de l'amélioration de la sécurité des patients ou un simple gadget ?

The launch on the market of a new compound is always an important event for a specialty, particularly when the mechanism of action is completely new. It is the case with sugammadex, a cyclodextrin able to encapsulate specifically and only nondepolarizing steroidal muscles relaxant, rocuronium or vecuronium. The clinical trials which have been performed for sugammadex approval have demonstrated promising results. Sugammadex is able to rapidly reverse (2-5 min) different levels of neuromuscular blockade: moderate (e.g., T2 recovery), deep (e.g., PTC 1-2 recovery) and also few minutes (3-15) after rocuronium administration. Thus, the sugammadex's onset time is about 10 times more rapid than neostigmine without the need of concomitantly atropine administration. Sugammadex has only been tested in small sample size of patients. Therefore, the exact place in the anesthetic practice, the potential indications, the safety profile on a large-scale, thus remain to determine. In particular, how it will modify our current practices characterized to date by 1) under-use of neuromuscular monitoring, 2) a marginal practice of reversal and 3) a wide use of benzylisoquinolines : atracurium and cis-atracurium? Finally, what will be the medical strategies to justify an additional cost when compared to neostigmine?