Topical noninvasive retinal drug delivery of a tyrosine kinase inhibitor: 3% cediranib maleate cyclodextrin nanoparticle eye drops in the rabbit eye.

PURPOSE: Tyrosine kinase inhibitors inhibit VEGF receptors. If delivered to the retina, they might inhibit oedema and neovascularization such as in age-related macular degeneration and diabetic retinopathy. The aim of this study was to formulate cediranib maleate, a potent VEGF inhibitor, as γ-cyclodextrin nanoparticle eye drops and measure the retinal delivery and overall ocular pharmacokinetics after a single-dose administration in rabbits. METHODS: A novel formulation technology with 3% cediranib maleate as γ-cyclodextrin micro-suspension was prepared by autoclaving method. Suitable stabilizers were tested for heat-stable eye drops. The ophthalmic formulation was topically applied to one eye in rabbits. The pharmacokinetics in ocular tissues, tear film and blood samples were studied at 1, 3 and 6 hr after administration. RESULTS: γ-cyclodextrin formed complex with cediranib maleate. The formation of γ-cyclodextrin nanoparticles occurred in concentrated complexing media. Combined stabilizers prevented the degradation of drug during the autoclaving process. Three hours after administration of the eye drops, treated eyes showed cediranib levels of 737 ± 460 nM (mean ± SD) in the retina and 10 ± 6 nM in the vitreous humour. CONCLUSIONS: Cediranib maleate in γ-cyclodextrin nanoparticles were stable to heat in presence of stabilizers. The drug as eye drops reached the retina in concentrations that are more than 100 times higher than the 0.4 nM IC50 value reported for the VEGF type-II receptor and thus, presumably, above therapeutic level. These results suggest that γ-cyclodextrin-based cediranib maleate eye drops deliver effective drug concentrations to the retina in rabbits after a single-dose administration.

Exploring Charged Polymeric Cyclodextrins for Biomedical Applications.

Over the years, cyclodextrin uses have been widely reviewed and their proprieties provide a very attractive approach in different biomedical applications. Cyclodextrins, due to their characteristics, are used to transport drugs and have also been studied as molecular chaperones with potential application in protein misfolding diseases. In this study, we designed cyclodextrin polymers containing different contents of ß- or γ-cyclodextrin, and a different number of guanidinium positive charges. This allowed exploration of the influence of the charge in delivering a drug and the effect in the protein anti-aggregant ability. The polymers inhibit Amiloid ß peptide aggregation; such an ability is modulated by both the type of CyD cavity and the number of charges. We also explored the effect of the new polymers as drug carriers. We tested the Doxorubicin toxicity in different cell lines, A2780, A549, MDA-MB-231 in the presence of the polymers. Data show that the polymers based on γ-cyclodextrin modified the cytotoxicity of doxorubicin in the A2780 cell line.

Delivering Crocetin across the Blood-Brain Barrier by Using γ-Cyclodextrin to Treat Alzheimer's Disease.

Crocetin (CRT) has shown various neuroprotective effects such as antioxidant activities and the inhibition of amyloid ß fibril formation, and thus is a potential therapeutic candidate for Alzheimer's disease (AD). However, poor water solubility and bioavailability are the major obstacles in formulation development and pharmaceutical applications of CRT. In this study, a novel water-soluble CRT-γ-cyclodextrin inclusion complex suitable for intravenous injection was developed. The inclusion complex was nontoxic to normal neuroblastoma cells (N2a cells and SH-SY5Y cells) and AD model cells (7PA2 cells). Furthermore, it showed stronger ability to downregulate the expression of C-terminus fragments and level of amyloid ß in 7PA2 cell line as compared to the CRT free drug. Both inclusion complex and CRT were able to prevent SH-SY5Y cell death from H2O2-induced toxicity. The pharmacokinetics and biodistribution studies showed that CRT-γ-cyclodextrin inclusion complex significantly increased the bioavailability of CRT and facilitated CRT crossing the blood-brain barrier to enter the brain. This data shows a water-soluble γ-cyclodextrin inclusion complex helped to deliver CRT across the blood-brain barrier. This success should fuel further pharmaceutical research on CRT in the treatment for AD, and it should engender research on γ-cyclodextrin with other drugs that have so far not been explored.

Sugammadex: A Review of Neuromuscular Blockade Reversal.

Sugammadex (Bridion(®)) is a modified γ-cyclodextrin that reverses the effect of the steroidal nondepolarizing neuromuscular blocking agents rocuronium and vecuronium. Intravenous sugammadex resulted in rapid, predictable recovery from moderate and deep neuromuscular blockade in patients undergoing surgery who received rocuronium or vecuronium. Recovery from moderate neuromuscular blockade was significantly faster with sugammadex 2 mg/kg than with neostigmine, and recovery from deep neuromuscular blockade was significantly faster with sugammadex 4 mg/kg than with neostigmine or spontaneous recovery. In addition, recovery from neuromuscular blockade was significantly faster when sugammadex 16 mg/kg was administered 3 min after rocuronium than when patients spontaneously recovered from succinylcholine. Sugammadex also demonstrated efficacy in various special patient populations, including patients with pulmonary disease, cardiac disease, hepatic dysfunction or myasthenia gravis and morbidly obese patients. Intravenous sugammadex was generally well tolerated. In conclusion, sugammadex is an important option for the rapid reversal of rocuronium- or vecuronium-induced neuromuscular blockade.

Effect of 18ß-glycyrrhetinic acid and hydroxypropyl γcyclodextrin complex on indomethacin-induced small intestinal injury in mice.

Non-steroidal anti-inflammatory drugs (NSAIDs)-induced small intestinal injury is a serious clinical event with recent advances of diagnostic technologies, but a successful therapeutic method to treat such injuries is still lacking. Licorice, a traditional herbal medicine, and its derivatives have been widely used for the treatment of a variety of diseases due to their extensive biological actions. However, it is unknown whether these derivatives have an effect on NSAIDs-induced small intestinal damage. Previously, the anti-inflammatory effects of three compounds extracted from the licorice root, glycyrrhizin, 18ß-glycyrrhetinic acid, and dipotassium glycyrrhizinate, were compared in vitro cell culture. The most prominent inhibitory effect on the tumor necrosis factor-α (TNF-α) production was observed with the administration of 18ß-glycyrrhetinic acid as an active metabolite of glycyrrhizin. In this study, a complex compound of 18ß-glycyrrhetinic acid and hydroxypropyl γcyclodextrin was examined to improve the oral bioavailability. After administration of this complex to indomethacin treated mice, a significantly high plasma concentration of 18ß-glycyrrhetinic acid was detected using the tandem mass spectrometry coupled with the HPLC. Furthermore, the complex form of 18ß-glycyrrhetinic acid and hydroxypropyl γcyclodextrin reduced mRNA expressions of TNF-α, interleukin (IL)-1ß, and IL-6, which was histologically confirmed in the improvement of indomethacin-induced small intestinal damage. These results suggest that the complex of 18ß-glycyrrhetinic acid and hydroxypropyl γcyclodextrin has the potential therapeutic value for preventing the adverse effects of indomethacin-induced small intestinal injury.

Dialysability of sugammadex and its complex with rocuronium in intensive care patients with severe renal impairment.

BACKGROUND: Renal excretion is the primary route for the elimination of sugammadex. We evaluated the dialysability of sugammadex and the sugammadex-rocuronium complex in patients with severe renal impairment in the intensive care unit (ICU). METHODS: Six patients in the ICU with acute severe renal impairment received general anaesthesia for transoesophageal echocardiography, to replace their tracheal tubes, or for bronchoscopy. Five of the six patients were in the ICU after cardiac/vascular surgery and one for pneumonia-induced respiratory failure. They all received rocuronium 0.6 mg kg(-1), followed 15 min later by sugammadex 4.0 mg kg(-1). Two patients were studied for two dialysis episodes and four patients for four episodes. Rocuronium and sugammadex concentrations were measured in plasma and dialysate at several time points before, during, and after high-flux dialysis. Dialysis clearance in plasma and dialysate, and reduction ratio (RR) (the extent of the plasma concentration reduction at the end of a dialysis episode when compared with before dialysis) were calculated for each dialysis episode. RESULTS: Dialysis episodes lasted on average 6 h. Observed RRs indicated mean reductions of 69% and 75% in the plasma concentrations of sugammadex and rocuronium, respectively, during the first dialysis episode. Reductions were around 50% during sequential dialysis episodes. On average, dialysis clearance of sugammadex and rocuronium in blood was 78 and 89 ml min(-1), respectively. CONCLUSIONS: Haemodialysis using a high-flux dialysis method is effective in removing sugammadex and the sugammadex-rocuronium complex in patients with severe renal impairment.

Flucloxacillin and diclofenac do not cause recurrence of neuromuscular blockade after reversal with sugammadex.

BACKGROUND: Sugammadex, a modified γ-cyclodextrin, facilitates rapid reversal of rocuronium- and vecuronium-induced neuromuscular blockade (NMB). Cyclodextrins are known for their ability to form inclusion complexes with various drugs. Theoretically, molecules with a high affinity for sugammadex could interact and displace sugammadex from the sugammadex-rocuronium or sugammadex-vecuronium complex, potentially resulting in the recurrence of NMB due to recirculation of free rocuronium or vecuronium. OBJECTIVE: This study aimed to evaluate whether the administration of high doses of flucloxacillin or diclofenac can result in recurrence of NMB through displacement of sugammadex from its complex with rocuronium or vecuronium, following successful reversal of NMB by a suboptimal dose of sugammadex 2 mg/kg. Flucloxacillin has previously been identified using a modelling approach as a drug with displacement potential, while diclofenac was assessed due to its common intravenous use in the peri-operative and post-surgery setting. METHODS: This was a randomized, open-label, parallel, single-centre study conducted at SGS Life Services-CPU, Antwerp, Belgium. Twenty-four healthy, propofol-anaesthetized, adult volunteers were randomized to either rocuronium 0.6 mg/kg or vecuronium 0.1 mg/kg, followed by a suboptimal dose of sugammadex 2 mg/kg 15 minutes after induction of NMB. Five minutes after successful sugammadex reversal, subjects received either diclofenac 75 mg (15-minute infusion) or flucloxacillin 2 g (5-minute infusion) according to randomization. The suboptimal dose of sugammadex and relatively high doses of diclofenac and flucloxacillin were applied to create favourable conditions for the potential displacement of sugammadex from the sugammadex-rocuronium or sugammadex-vecuronium complex, and thus possible recurrence of NMB due to recirculation of free rocuronium or vecuronium. Possible recurrence of NMB was assessed by neuromuscular monitoring, performed with acceleromyography, and was continued until ∼90 minutes after the start of diclofenac or flucloxacillin administration. Recurrence of NMB was concluded if three consecutive train-of-four (TOF) ratios were <0.8. RESULTS: Following successful reversal with a suboptimal dose of sugammadex 2 mg/kg administered 15 minutes after NMB induction, subsequent administration of diclofenac or flucloxacillin did not result in recurrence of NMB in any subject based on measurement of TOF ratios during anaesthesia and neuromuscular function tests upon awakening. There were no adverse events considered to be related to sugammadex. CONCLUSION: Administration of flucloxacillin or diclofenac does not result in recurrence of NMB through displacement of sugammadex from the sugammadex-rocuronium or sugammadex-vecuronium complex.

Efficacy, safety, and pharmacokinetics of sugammadex for the reversal of rocuronium-induced neuromuscular blockade in elderly patients.

BACKGROUND: The management of elderly patients can be challenging for anesthesiologists for many reasons, including altered pharmacokinetics and dynamics. This study compared the efficacy, safety, and pharmacokinetics of sugammadex for moderate rocuronium-induced neuromuscular blockade reversal in adult (aged 18-64 yr) versus elderly adult (aged 65 yr or older) patients. METHODS: This phase 3a, multicenter, parallel-group, comparative, open-label study enrolled 162 patients aged 18 yr and older, American Society of Anesthesiologists class 1-3, scheduled for surgery with general anesthesia and requiring neuromuscular blockade. After anesthesia induction, patients received rocuronium, 0.6 mg/kg, before tracheal intubation, with maintenance doses of 0.15 mg/kg as required. At the end of surgery, patients received sugammadex, 2.0 mg/kg, at reappearance of the second twitch of the train-of-four (TOF) for reversal. The primary efficacy variable was time from sugammadex administration to recovery of the TOF ratio to 0.9 or greater. Pharmacokinetics and safety were also evaluated. RESULTS: Overall, 150 patients were treated and had at least one postbaseline efficacy assessment; 48 were aged 18-64 yr (adult), 62 were aged 65-74 yr (elderly), and 40 were aged 75 yr or older (old-elderly). The geometric mean time (95% confidence interval) from sugammadex administration to recovery of the TOF ratio to 0.9 increased with age, from 2.3 (2.0-2.6) min (adults) to 2.9 (2.7-3.2) min (elderly/old-elderly groups combined). Recovery of the TOF ratio to 0.9 was estimated to be 0.7 min faster in adults compared with patients aged 65 yr or older (P = 0.022). Sugammadex was well tolerated by all patients. CONCLUSION: Sugammadex facilitates rapid reversal from moderate rocuronium-induced neuromuscular blockade in adults of all ages.

Assessment of the potential for displacement interactions with sugammadex: a pharmacokinetic-pharmacodynamic modelling approach.

BACKGROUND: Sugammadex is a γ-cyclodextrin that binds with high affinity to the neuromuscular blocking agents (NMBAs) rocuronium (bromide) and vecuronium (bromide) by encapsulation. Cyclodextrins are known to form inclusion complexes with other compounds. OBJECTIVES: We utilized a previously developed pharmacokinetic-pharmacodynamic model to identify potential clinically relevant displacement interactions with sugammadex. The potential for sugammadex to capture other drug molecules, thereby reducing their efficacy, is not discussed here. METHODS: Isothermal titration calorimetry (ITC) was used to determine the binding affinity (estimated by association rate constant [k(ass)]) between sugammadex and 300 commonly prescribed drugs. The screening included drugs commonly used in or shortly after anaesthesia, commonly prescribed drugs such as antidepressants and cardiovascular drugs, drugs (both steroidal and nonsteroidal) acting on steroidal receptors (such as the corticosteroids hydrocortisone, prednisolone and dexamethasone), and the selective estrogen receptor modulator toremifene. The model took into account the population pharmacokinetic-pharmacodynamic relationships of sugammadex, rocuronium and vecuronium, the binding affinities of the NMBAs and other compounds as determined by ITC, and the relationship between the free concentration of NMBA with sugammadex in the presence of a third complexed compound. Using the model, the critical concentrations of a concomitantly administered compound required to result in a train-of-four (TOF) ratio of <0.9, indicating reoccurrence of neuromuscular blockade, for each plasma concentration of sugammadex and NMBA were calculated. For compounds with a k(ass) value of ≥ 2.5 × 104 mol/L likely to be administered during sugammadex reversal, the combinations of k(ass) and maximum plasma drug concentration (C(max)) were entered into a graph, consisting of a critical line established using a conservative approach, and those compounds above this critical line potentially resulting in a TOF ratio <0.9 were subsequently identified. Clinical validation was performed in a post hoc analysis of data from ten sugammadex studies, in which the impact of various drugs administered perioperatively on neuromuscular recovery was assessed for up to 1 hour after sugammadex administration. RESULTS: ITC analysis demonstrated that the binding affinity of rocuronium and vecuronium for sugammadex was very high, with k(ass) values of 1.79 × 107 mol/L and 5.72 × 106 mol/L, respectively. Only three compounds (flucloxacillin, fusidic acid and toremifene) were found to have critical combinations of k(ass) and C(max), and thus the potential for displacement. Sugammadex was administered to 600 patients for reversal of rocuronium- or vecuronium-induced blockade in the ten analysed studies, in which 21 co-administered drugs were selected for analysis. No reoccurrence of blockade occurred in any patient. CONCLUSION: Of 300 drugs screened, only three (flucloxacillin, fusidic acid and toremifene) were found to have potential for a displacement interaction with sugammadex, which might potentially be noticed as a delay in recovery of the TOF ratio to 0.9. A clinical study found no evidence of a clinically relevant displacement interaction of flucloxacillin with sugammadex; these findings confirm the highly conservative nature of the modelling and simulation assumptions in the present study.

Sugammadex--a short review and clinical recommendations for the cardiac anesthesiologist.

This review outlines the basic pharmacodynamic and pharmacokinetic properties of sugammadex for the cardiac anesthesiologist. It describes the different clinical scenarios when sugammadex can be used during cardiac surgery and gives clinical recommendations. Sugammadex is a unique reversal drug that binds a chemical complex with rocuronium and vecuronium, by which the neuromuscular blockade is quickly reversed. It is free of any clinical side-effects and doses of 2 mg/kg or more reliably reverse neuromuscular blockade within 5-15 min, depending on the depth of the neuromuscular blockade. Doses below 2 mg/kg should be avoided at any time because of the inherent risk of recurarization. Sugammadex should not replace good clinical practice--titration of neuromuscular blocking drugs to clinical needs and objective monitoring of neuromuscular blockade in the operating room or intensive care unit. Neuromuscular transmission should be determined in all patients before sugammadex is considered and 5 min after its administration to ensure that extubation is performed with normal neuromuscular transmission.

Update on neuromuscular pharmacology.

PURPOSE OF REVIEW: We review the efficacy and safety of gantacurium and AV002, two novel, investigational fumarate-based nondepolarizing neuromuscular blockers, as well as sugammadex and cysteine, two novel reversal drugs that have no acetylcholinesterase inhibition properties. RECENT FINDINGS: Gantacurium (with a pharmacodynamic profile similar to that of succinylcholine) and AV002 (with an intermediate duration of action) have shown efficacy in animals and, for gantacurium, in humans. Animal data have shown that exogenous administration of the amino acid cysteine accelerates the natural chemical degradation of both gantacurium and AV002 via the cysteine adduction pathway. Another reversal drug, sugammadex (a modified gamma-cyclodextrin and the first selective relaxant binding agent), forms very tight complexes in a 1: 1 ratio with steroidal neuromuscular blocking agents. SUMMARY: In a multicenter phase-2 randomized controlled study in the European Union, the efficacy and safety of gantacurium were evaluated, but results have not yet been published. Sugammadex is currently available in the European Union, but the United States Food and Drug Administration has had concerns about its safety (hypersensitivity and allergic reactions) and has asked for additional safety data. It is hoped that the widespread use of sugammadex in the European Union will provide additional information.

Sugammadex: a cyclodextrin to reverse neuromuscular blockade in anaesthesia.

BACKGROUND: Neuromuscular blocking agents are used to provide relaxation and immobility during surgery. To avoid residual paralysis after anaesthesia, reversal of blockade is commonly accomplished with anticholinesterase agents but these drugs have cardiovascular side effects and incomplete effectiveness. Sugammadex is a cyclodextrin that binds rocuronium and chemically similar neuromuscular blocking drugs. OBJECTIVE: Published data on the effectiveness of sugammadex as a reversal agent were examined. METHODS: Peer-reviewed articles on residual postoperative paralysis and sugammadex (ORG 25969) were analysed. RESULTS: Rocuronium-sugammadex complexes are formed and excreted via the kidney. The dissociation constant of the reaction is estimated at 0.1 microM. Sugammadex produces more rapid reversal of rocuronium- and vecuronium-induced blockade than current reversal agents. The dose required depends directly on intensity of blockade. To date, there appear to be few side effects. Inadequate dosage may lead to reparalysis. CONCLUSION: More data are needed, especially in patients with renal failure and those who require neuromuscular blockade again soon after receiving sugammadex.

Sugammadex: a novel agent for the reversal of neuromuscular blockade.

To achieve spontaneous ventilation after completion of surgery, the nondepolarizing effects on skeletal muscle relaxation are often reversed by administration of an acetylcholinesterase inhibitor. However, these agents increase acetylcholine at both the neuromuscular junction and the muscarinic receptors. Therefore, coadministration of an anticholinergic agent is required to prevent parasympathetic adverse effects. In addition, a relative pharmacologic ceiling effect is seen with inhibition of acetylcholinesterase, necessitating some recovery of neuromuscular function before an acetylcholinesterase inhibitor is administered. Sugammadex is a new modified gamma-cyclodextrin compound under clinical investigation in the United States. It does not interact with cholinergic mechanisms to elicit reversal. Instead, it is a selective relaxant binding agent and acts by forming a 1:1 complex with steroidal nondepolarizing neuromuscular blockers in the plasma, lowering the effective concentration available at the receptor. Due to its selectivity, sugammadex does not inhibit the effects of nondepolarizing agents of the benzylisoquinolinium class. In contrast to acetylcholinesterase inhibition, sugammadex is effective even when administered during profound blockade, and it does not require coadministration of an anticholinergic agent. It provides a novel mechanism of action for reversal of the neuromuscular block induced by nondepolarizing aminosteroidal agents.