Encapsulation Dynamics of Neuromuscular Blocking Drugs by Sugammadex.

BACKGROUND: The clinical actions of sugammadex have been well studied, but the detailed molecular mechanism of the drug encapsulation process has not been systematically documented. The hypothesis was that sugammadex would attract rocuronium and vecuronium via interaction with the sugammadex side-chain "tentacles," as previously suggested. METHODS: Computational molecular dynamics simulations were done to investigate docking of sugammadex with rocuronium and vecuronium. To validate these methods, strength of binding was assessed between sugammadex and a heterogeneous group of nine other drugs, the binding affinities of which have been experimentally determined. These observations hinted that high concentrations of unbound sugammadex could bind to propofol, potentially altering its pharmacokinetic profile. This was tested experimentally in in vitro cortical slices. RESULTS: Sugammadex encapsulation of rocuronium involved a sequential progression down a series of metastable states. After initially binding beside the sugammadex molecule (mean ± SD center-of-mass distance = 1.17 ± 0.13 nm), rocuronium then moved to the opposite side to that hypothesized, where it optimally aligned with the 16 hydroxyl groups (distance, 0.82 ± 0.04 nm) before entering the sugammadex cavity to achieve energetically stable encapsulation by approximately 120 ns (distance, 0.35 ± 0.12 nm). Vecuronium formed fewer hydrogen bonds with sugammadex than did rocuronium; hence, it was less avidly bound. For the other molecules, the computational results showed good agreement with the available experimental data, showing a clear bilogarithmic relation between the relative binding free energy and the association constant (R2 = 0.98). Weaker binding was manifest by periodic unbinding. The brain slice results confirmed the presence of a weak propofol-sugammadex interaction. CONCLUSIONS: Computational simulations demonstrate the dynamics of neuromuscular blocking drug encapsulation by sugammadex occurring from the opposite direction to that hypothesized and also how high concentrations of unbound sugammadex can potentially weakly bind to other drugs given during general anesthesia.

Utility of neuromuscular blockade reversal in the evaluation of acute neurosurgical patients: A retrospective case-series.

OBJECTIVE: Sugammadex reversal of neuromuscular blocking agents (NMBAs) is usually performed postoperatively. A scarcity of literature exists exploring sugammadex use for timely neurological examination of neurosurgical patients. NMBAs, like rocuronium, are used in the Emergency Department during intubation and their unpredictable duration of action often impedes timely and accurate assessment of patient neurological status. We aim to explore the role of sugammadex in evaluating patients in need of acute neurosurgical care. METHODS: Retrospective assessment of patients presenting with traumatic brain injury or intracranial hemorrhage was conducted at our level 1 trauma center. Patients of interest were those for whom sugammadex reversal of rocuronium neuromuscular blockade, from intubating doses, was pursued to ensure timely neurologic assessment. Nine patients were identified for whom GCS pre-/post-sugammadex, rocuronium dosing, elapsed time between rocuronium administration and reversal, and clinical course data were retrieved. RESULTS: Arrival GCS was 5.2 ± 3.2, with intubation accomplished within 10 ± 2.5 min of presentation. Rocuronium dosing was consistent between patients, average single dose of 1.2 ± 0.3 mg/kg. Lingering neuromuscular blockade ranged from 28 to 132 min (87.3 ± 34.3 min). All patients exhibited a GCS of 3 T upon initial neurosurgical evaluation, prior to reversal. Post-reversal GCS rose to 6.0 T ± 2.2. Sugammadex facilitated more accurate clinical decision making in 8 of 9 patients, including prevention of unnecessary invasive procedures. Two of 9 patients were eventually discharged home or to a rehabilitation facility. CONCLUSIONS: Rocuronium neuromuscular blockade can linger beyond pharmacokinetic predictions, thus delaying timely and precise neurologic assessment. Our data suggests sugammadex may be a useful addition to the clinician's armamentarium for acute neurologic assessment in the neurosurgical population. Sugammadex may impact clinical decision-making in certain patients and allow for more informed decision-making by families and physicians alike. Prospective studies are needed to definitively assess the impact of sugammadex on outcomes in acute neurosurgical settings.

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.

Safety, tolerability, and pharmacokinetics of adamgammadex sodium, a novel agent to reverse the action of rocuronium and vecuronium, in healthy volunteers.

Neuromuscular blockers (NMBs) selectively block neuromuscular transmission at the N2-nicotinic receptor on motor neurons to paralyze skeletal muscles, and are mainly used to facilitate tracheal intubation and surgical procedures. Rapid reversal is necessary in clinical practice to avoid profound block and reduce recovery time. Adamgammadex sodium is a modified γ-cyclodextrin derivative consisting of a lipophilic core and a hydrophilic outer end that forms an inactive tight inclusion complex with free molecules of rocuronium and vecuronium. In preclinical study, adamgammadex produced a concentration-dependent reversion effect of neuromuscular blockade induced by rocuronium in beagle dogs. Furthermore, adamgammadex had a less potential side effects than sugammadex and other clinical used neuromuscular block antagonists. In this study, the objective was to assess the safety, tolerability, and pharmacokinetics of single intravenous injection of adamgammadex in healthy volunteers. Approved by the China Food and Drug Administration, 52 healthy volunteers (half male and half female) were enrolled in this single-center, randomized, double-blind placebo-controlled study. No serious adverse effects were happened in this study. The overall frequency of adverse effects in adamgammadex was similar for that in placebo, and there was no specific adverse effect in adamgammadex. All of the volunteers bearing the adverse effects were recovered to normal without any treatment or intervention. In pharmacokinetic study, the value of half-time, Tmax, and clearance were not changed significantly, and the Cmax and AUC0-∞ increased with a similar ratio of the escalating doses. For dose proportionality analysis of adamgammadex, the estimate of slope was close to 1, and it was not significantly different from 1 after doses (AUC0-∞, 0.9965 [90%CI, 0.9468, 1.046]; Cmax, 0.9462 [90%CI, 0.8800, 1.012]). Therefore, adamgammadex exposure in plasma increased in a dose- proportional manner. The urinary route is a significant excretory pathway for adamgammadex, and it is mostly completed at 8 h. All the results in this study showed that adamgammadex may be a novel safe neuromuscular blockade reversal agent .

S-protected thiolated cyclodextrins as mucoadhesive oligomers for drug delivery.

AIM: The purpose of this study was to develop a novel mucoadhesive thiolated and S-protected gamma cyclodextrin (γ-CD) with an intact ring backbone to assure a prolonged residence time at specific target sites. METHOD: Thiolated γ-CD was generated through bromine substitution of its hydroxyl groups followed by replacement to thiol groups using thiourea. In the second step, thiol groups were protected by disulfide bond formation with 2-mercaptonicotinic acid (2-MNA). RESULT: Thiolated γ-CD displayed 1385 ±â€¯84 µmol thiol groups per gram of oligomer and the amount of MNA determined in the S-protected oligomer was 1153 ±â€¯41 µmol per gram of oligomer. In-vitro screening of mucoadhesive properties of thiolated and S-protected γ-CD was done by two methods. Rheological investigation revealed the conjugates non-mucolytic with only a slight increase in viscosity of thiolated and S-protected γ-CD as compared to unmodified γ-CD, whereas mucoadhesive properties of the new thiolated and S-protected γ-CD performed on freshly excised porcine intestinal mucosa showed 44.4- and 50.9-fold improvement in mucoadhesion, respectively. The new conjugates did not show any cytotoxicity to Caco-2 cells even at a concentration of 1% (m/v) for 24 h. In addition, in-vitro studies of α-amylase degradation of γ-CD, γ-CD-SH and γ-CD-SS-MNA confirmed that all conjugates are biodegradable. CONCLUSION: These outcomes predict that these new conjugates of γ-CD might provide a new favorable tool for drug delivery providing a prolonged residence time on mucosal surfaces.

Pharmacokinetics of sugammadex in subjects with moderate and severe renal impairment
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AIMS: Sugammadex rapidly reverses moderate and deep rocuronium- or vecuronium-induced neuromuscular blockade at doses of 4 mg/kg and 2 mg/kg, respectively. Sugammadex is renally eliminated. This study evaluated the pharmacokinetics of sugammadex in subjects with renal impairment versus those with normal renal function. METHODS: This open-label, two-part, phase 1 study included adults with moderate (creatinine clearance (CLcr) 30 - < 50 mL/min) and severe (CLcr < 30 mL/min) renal impairment and healthy controls (CLcr ≥ 80 mL/min). A single intravenous (IV) bolus injection of sugammadex 4 mg/kg was administered into a peripheral vein over 10 seconds directly by straight needle in part 1 (n = 24; 8/group), and via an IV catheter followed by a saline flush in part 2 (n = 18; 6/group). Plasma concentrations of sugammadex were collected after drug administration. Due to dosing issues in part 1, pharmacokinetic parameters were determined for part 2 only. Safety was assessed throughout the study. RESULTS: Pharmacokinetic data were obtained from 18 subjects. Mean sugammadex exposure (AUC0-∞) in subjects with moderate and severe renal impairment was 2.42- and 5.42-times, respectively, that of healthy controls. Clearance decreased and apparent terminal half-life was prolonged with increasing renal dysfunction. Similar Cmax values were observed in subjects with renal impairment and healthy controls. There were no serious adverse events. CONCLUSIONS: Sugammadex exposure is increased in subjects with moderate and severe renal insufficiency due to progressively decreased clearance as a function of worsening renal function. Sugammadex 4 mg/kg was well tolerated in subjects with renal impairment, with a safety profile similar to that of healthy subjects. These results indicate that dose adjustment of sugammadex is not required in patients with moderate renal impairment; however, current safety experience is insufficient to support the use of sugammadex in patients with CLcr < 30 mL/min.
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γ-Cyclodextrin.

γ-Cyclodextrin (γCD) is a cyclic oligosaccharide formed by bacterial digestion of starch and used as solubilizing agent and stabilizer in a variety of pharmaceutical and food products. γCD is a large (molecular weight 1297Da) hydrophilic molecule that does not readily permeate biological membranes and is rapidly digested by bacteria in the gastrointestinal tract. In humans γCD is metabolized by α-amylase that is found in, for example, saliva, bile fluid and tears. Thus, bioavailability of γCD is negligible. Also, γCD is readily excreted unchanged in the urine after parenteral administration. Like other cyclodextrins, γCD can form water-soluble inclusion complexes with many poorly-soluble compounds. In comparison with the natural αCD and ßCD, γCD has the largest hydrophobic cavity, highest water solubility and the most favorable toxicological profile. The focus of this review is production, physiochemical properties, pharmacokinetics, toxicity and applications of γCD and its derivatives. Also, the aggregation behavior of γCD in aqueous media is discussed.

Bioavailability of an R-α-Lipoic Acid/γ-Cyclodextrin Complex in Healthy Volunteers.

R-α-lipoic acid (R-LA) is a cofactor of mitochondrial enzymes and a very strong antioxidant. R-LA is available as a functional food ingredient but is unstable against heat or acid. Stabilized R-LA was prepared through complexation with γ-cyclodextrin (CD), yielding R-LA/CD. R-LA/CD was orally administered to six healthy volunteers and showed higher plasma levels with an area under the plasma concentration-time curve that was 2.5 times higher than that after oral administration of non-complexed R-LA, although the time to reach the maximum plasma concentration and half-life did not differ. Furthermore, the plasma glucose level after a single oral administration of R-LA/CD or R-LA was not affected and no side effects were observed. These results indicate that R-LA/CD could be easily absorbed in the intestine. In conclusion, γ-CD complexation is a promising technology for delivering functional but unstable ingredients like R-LA.

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.

A PK-PD model-based assessment of sugammadex effects on coagulation parameters.

Exposure-response analyses of sugammadex on activated partial thromboplastin time (APTT) and prothrombin time international normalized ratio (PT(INR)) were performed using data from two clinical trials in which subjects were co-treated with anti-coagulants, providing a framework to predict these responses in surgical patients on thromboprophylactic doses of low molecular weight or unfractionated heparin. Sugammadex-mediated increases in APTT and PT(INR) were described with a direct effect model, and this relationship was similar in the presence or absence of anti-coagulant therapy in either healthy volunteers or surgical patients. In surgical patients on thromboprophylactic therapy, model-based predictions showed 13.1% and 22.3% increases in respectively APTT and PT(INR) within 30min after administration of 16mg/kg sugammadex. These increases remain below thresholds seen following treatment with standard anti-coagulant therapy and were predicted to be short-lived paralleling the rapid decline in sugammadex plasma concentrations.

Efficacy, safety and pharmacokinetics of sugammadex 4 mg kg-1 for reversal of deep neuromuscular blockade in patients with severe renal impairment.

BACKGROUND: This study evaluated efficacy and safety of sugammadex 4 mg kg(-1) for deep neuromuscular blockade (NMB) reversal in patients with severe renal impairment (creatinine clearance [CLCR] <30 ml min(-1)) vs those with normal renal function (CLCR ≥80 ml min(-1)). METHODS: Sugammadex 4 mg kg(-1) was administered at 1-2 post-tetanic counts for reversal of rocuronium NMB. Primary efficacy variable was time from sugammadex to recovery to train-of-four (T4/T1) ratio 0.9. Equivalence between groups was demonstrated if two-sided 95% CI for difference in recovery times was within -1 to +1 min interval. Pharmacokinetics of rocuronium and overall safety were assessed. RESULTS: The intent-to-treat group comprised 67 patients (renal n=35; control n=32). Median (95% CI) time from sugammadex to recovery to T4/T1 ratio 0.9 was 3.1 (2.4-4.6) and 1.9 (1.6-2.8) min for renal patients vs controls. Estimated median (95% CI) difference between groups was 1.3 (0.6-2.4) min; thus equivalence bounds were not met. One control patient experienced acceleromyography-determined NMB recurrence, possibly as a result of premature sugammadex (4 mg kg(-1)) administration, with no clinical evidence of NMB recurrence observed. Rocuronium, encapsulated by Sugammadex, was detectable in plasma at day 7 in 6 patients. Bioanalytical data for sugammadex were collected but could not be used for pharmacokinetics. CONCLUSIONS: Sugammadex 4 mg kg(-1) provided rapid reversal of deep rocuronium-induced NMB in renal and control patients. However, considering the prolonged sugammadex-rocuronium complex exposure in patients with severe renal impairment, current safety experience is insufficient to support recommended use of sugammadex in this population. CLINICAL TRIAL REGISTRATION: NCT00702715.

Pharmacokinetics of sugammadex 16 mg/kg in healthy Chinese volunteers.

OBJECTIVE: Elimination of sugammadex occurs predominantly via the kidneys, with the majority of the drug excreted unchanged in the urine. To date, most studies with sugammadex have been performed in non-Asian populations. The objectives of this open-label study were to determine the pharmacokinetics (PK) and safety of single-dose sugammadex (16 mg/kg) in healthy Chinese adult volunteers. METHODS: 12 Chinese subjects (6 male; 6 female) received intravenous sugammadex (16 mg/kg) as a 10-second bolus infusion. Blood samples were collected pre-sugammadex and at regular intervals up to 24 hours post-sugammadex for PK assessment. Safety was assessed via AEs, vital signs, electrocardiogram, and laboratory parameters. RESULTS: Following sugammadex 16 mg/kg infusion, peak sugammadex concentration was 197 µg/mL, clearance was 99.7 mL/min, and apparent volume of distribution at equilibrium was 10.5 L. Plasma sugammadex concentrations showed a polyexponential decline over time, with an overall geometric mean (CV%) terminal half-life of 145 minutes (17.9%) (139 minutes (17.7%) for males; 152 minutes (18.6%) for females). No influence of gender on the PK of sugammadex was observed. Three subjects experienced an adverse events (AE) (dysgeusia of mild intensity), which was considered possibly or probably related to sugammadex. There were no clinically significant changes in vital signs, electrocardiography or laboratory parameters. CONCLUSION: PK of sugammadex (16 mg/kg) was characterized in healthy Chinese subjects. Overall between-subject variability on clearance and apparent volume of distribution was ~ 10%. Sugammadex was generally well tolerated.

Optimized on-line enantioselective capillary electrophoretic method for kinetic and inhibition studies of drug metabolism mediated by cytochrome P450 enzymes.

Pharmacokinetic and pharmacodynamic properties of a chiral drug can significantly differ between application of the racemate and single enantiomers. During drug development, the characteristics of candidate compounds have to be assessed prior to clinical testing. Since biotransformation significantly influences drug actions in an organism, metabolism studies represent a crucial part of such tests. Hence, an optimized and economical capillary electrophoretic method for on-line studies of the enantioselective drug metabolism mediated by cytochrome P450 enzymes was developed. It comprises a diffusion-based procedure, which enables mixing of the enzyme with virtually any compound inside the nanoliter-scale capillary reactor and without the need of additional optimization of mixing conditions. For CYP3A4, ketamine as probe substrate and highly sulfated γ-cyclodextrin as chiral selector, improved separation conditions for ketamine and norketamine enantiomers compared to a previously published electrophoretically mediated microanalysis method were elucidated. The new approach was thoroughly validated for the CYP3A4-mediated N-demethylation pathway of ketamine and applied to the determination of its kinetic parameters and the inhibition characteristics in presence of ketoconazole and dexmedetomidine. The determined parameters were found to be comparable to literature data obtained with different techniques. The presented method constitutes a miniaturized and cost-effective tool, which should be suitable for the assessment of the stereoselective aspects of kinetic and inhibition studies of cytochrome P450-mediated metabolic steps within early stages of the development of a new drug.

Effects of sugammadex on activated partial thromboplastin time and prothrombin time in healthy subjects.

OBJECTIVES: To assess the impact of sugammadex on activated partial thromboplastin time (APTT) and international normalized ratio for prothrombin time (PT(INR)) in healthy subjects and characterize the concentration-dependency of sugammadex effects on APTT and prothrombin time (PT) in normal human plasma in vitro. METHODS: Eight healthy subjects (18 - 45 years of age) were administered intravenous doses of 4 mg/kg sugammadex, 16 mg/kg sugammadex, or placebo in a randomized, placebo-controlled, three period cross-over trial. The primary endpoint was area under the curve from 2 to 60 minutes post-dose (AUC2-60min) for APTT and PT(INR). In vitro, the effects of sugammadex on APTT and PT were assessed in pooled normal human citrate plasma. RESULTS: In subjects dosed with 4 and 16 mg/kg sugammadex, geometric mean ratios (treated vs. placebo) for AUC2-60min were 1.085 (95% confidence interval, 0.888 - 1.325) and 1.019 (0.868 - 1.195), respectively, for APTT, and 1.047 (0.904 - 1.213) and 1.096 (0.953 - 1.261), respectively, for PT(INR). At individual timepoints, mean APTT and PT(INR) increased by up to 22% after 16 mg/kg sugammadex compared with placebo. All such increases occurred within 30 minutes post-dose. Sugammadex was generally well tolerated. In the in vitro experiments, addition of sugammadex to plasma resulted in limited, concentration dependent increases in both APTT and PT. At 200 µg/mL (the mean maximum concentration reached therapeutically), the relative increases were 29% and 19%, respectively. CONCLUSIONS: Administration of sugammadex is associated with a dose-related, limited and transient prolongation of APTT and PT(INR) that is unlikely to be of clinical relevance.

Kinetics of γ-cyclodextrin nanoparticle suspension eye drops in tear fluid.

PURPOSE: We have developed nanoparticle γ-cyclodextrin dexamethasone (DexNP) and dorzolamide (DorzNP) eye drops that provide sustained high drug concentrations on the eye surface. To test these characteristics, we measured dexamethasone and dorzolamide levels in tear fluid in humans following eye drop administration. METHODS: Concentration of dexamethasone was measured by mass spectrometry. One drop of DexNP was instilled into one eye. Tear fluid was sampled with microcapillary pipettes at seven time-points after drop instillation. Control eyes received Maxidex(®) (dexamethasone). The same procedure was performed for dorzolamide with DorzNP and Trusopt(®) . RESULTS: Six subjects were included in each group. The peak concentration (µg/ml ± standard deviation) of dexamethasone for DexNP eye drops (636.6 ± 399.1) was up to 19-fold higher than with Maxidex(®) (39.3 ± 18.9) (p < 0.001). At 4 hr, DexNP was still 10 times higher than Maxidex(®) . In addition, DexNP resulted in about 30-fold higher concentration of dissolved dexamethasone in the tear fluid of extended time period allowing more drug to partition into the eye tissue. The overall concentration of dorzolamide was about 50% higher for DorzNP (59.5 ± 76.9) than Trusopt(®) (40.0 ± 76.7) (p < 0.05). CONCLUSION: The results indicate high and extended concentration of dissolved dexamethasone with DexNP, which can explain the greater and longer lasting effect of dexamethasone in the cyclodextrin nanoparticle drug delivery platform. Dexamethasone seems to fit the cyclodextrin nanoparticle suspension drug delivery platform with longer duration and higher concentrations in tear fluid than available commercial drops, while dorzolamide is less suitable.

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.

Enhancement of diosgenin distribution in the skin by cyclodextrin complexation following oral administration.

Orally administrated diosgenin, a steroidal saponin found in several plants including Dioscorea villosa, recovers skin thickness reduced in ovariectomized mice, and plays an important role in the treatment of hyperlipidemia. Thus, diosgenin is an active element of cosmeceutical and dietary supplements. However, we have already elucidated that the skin distribution and absolute oral bioavailability of diosgenin is very low. The aim of this study is to evaluate the efficacy of diosgenin-cyclodextrin (CD) complexes in improving the skin concentration of diosgenin. The formation of the CD complex was indicated by powder X-ray diffraction (XRD), differential scanning calorimetry (DSC), and scanning electron microscope (SEM) studies. Oral administration of the diosgenin/ß-CD complex resulted in a significant enhancement in terms of the skin distribution of diosgenin, maximum plasma level (C(max)), area under the plasma concentration-time curve (AUC), and absolute oral bioavailability over those of the drug alone. These results suggest that the inclusion complex of diosgenin/ß-CD can be used to improve low skin content of diosgenin.