Development of β-cyclodextrin/polyvinypyrrolidone-co-poly (2-acrylamide-2-methylpropane sulphonic acid) hybrid nanogels as nano-drug delivery carriers to enhance the solubility of Rosuvastatin: An in vitro and in vivo evaluation

The present study is aimed at enhancing the solubility of rosuvastatin (RST) by designing betacyclodextrin/polyvinypyrrolidone-co-poly (2-acrylamide-2-methylpropane sulphonic acid) crosslinked hydrophilic nanogels in the presence of crosslinker methylene bisacrylamide through free-radical polymerization method. Various formulations were fabricated by blending different amounts of betacyclodextrin, polyvinylpyrrolidone, 2-acrylamide-2-methylpropane sulphonic acid, and methylene bisacrylamide. The developed chemically crosslinked nanogels were characterized by FTIR, SEM, PXRD, TGA, DSC, sol-gel analysis, zeta size, micromeritics properties, drug loading percentage, swelling, solubility, and release studies. The FTIR spectrum depicts the leading peaks of resultant functional groups of blended constituents while a fluffy and porous structure was observed through SEM images. Remarkable reduction in crystallinity of RST in developed nanogels revealed by PXRD. TGA and DSC demonstrate the good thermal stability of nanogels. The size analysis depicts the particle size of the developed nanogels in the range of 178.5 ±3.14 nm. Drug loading percentage, swelling, solubility, and release studies revealed high drug loading, solubilization, swelling, and drug release patterns at 6.8 pH paralleled to 1.2 pH. In vivo experiments on developed nanogels in comparison to marketed brands were examined and better results regarding pharmacokinetic parameters were observed. The compatibility and non-toxicity of fabricated nanogels to biological systems was supported by a toxicity study that was conducted on rabbits. Efficient fabrication, excellent physicochemical properties, improved dissolution, high solubilization, and nontoxic nanogels might be a capable approach for the oral administration of poorly water-soluble drugs.

Molecular Dynamics Protocols for the Study of Cyclodextrin Drug Delivery Systems

Hypertension treatment is a current therapeutic priority as there is a constantly increasing part of the population that suffers from this risk factor, which may lead to cardiovascular and encephalic episodes and eventually to death. A number of marketed medicines consist of active ingredients that may be relatively potent; however, there is plenty of room to enhance their pharmacological profile and therapeutic index by improving specific physicochemical properties. In this work, we focus on a class of blood pressure regulators, called sartans, and we present the computational scheme for the pharmacological improvement of irbesartan (IRB) as a representative example. IRB has been shown to exert increased pharmacological action compared with other sartans, but it appears to be highly lipophilic and violates Lipinski rule (MLogP >4.15). To circumvent this drawback, proper hydrophilic molecules, such as cyclodextrins, can be used as drug carriers. This chapter describes the combinatory use of computational methods, namely molecular docking, quantum mechanics, molecular dynamics, and free energy calculations, to study the interactions and the energetic contributions that govern the IRB:cyclodextrin association. We provide a detailed computational protocol, which aims to assist the improvement of the pharmacological properties of sartans. This protocol can also be applied to any other drug molecule with diminished hydrophilic character.

Co-responsive smart cyclodextrin-gated mesoporous silica nanoparticles with ligand-receptor engagement for anti-cancer treatment

Combination of both internal- and external-stimuli responsive strategies in nanoplatforms can maximize therapeutic outcomes by overcoming drug efflux-mediated resistance and prolonging sustained release of therapeutic payloads in controlled and sequential manner. Here, we show a light/redox dual-stimuli responsive β-cyclodextrin (β-CD)-gated mesoporous silica nanoparticles (MSN) that can effectively load and seal the chemotherapeutics, doxorubicin (DOX), inside MSN with a dual-capped system. The primary gatekeeper was achieved by capping β-CD via a disulfide linkage. An azobenzene/galactose-grafted polymer (GAP) was introduced to functionalize the MSN surface through host-guest interaction. GAP not only served as a secondary non-covalent polymer-gatekeeper to further prevent molecules from leaking out, but also presented targeting ligand for engagement of the asialoglycoprotein receptor (ASGPR) on hepatocellular carcinoma (HepG2) cells. The controlled and stimuli release of DOX could be realized via dissociation of azobenzene moieties from β-CD cage upon UV-irradiation, followed by liberation with the endogenous glutathione. The in vitro studies verified the redox-sensitive DOX release behavior, and the UV irradiation could accelerate this process to trigger DOX burst from MSN-ss-CD/GAP. Notably, the DOX@MSN-ss-CD/GAP could more efficiently deliver DOX into HepG2 cells and demonstrate enhanced cytotoxicity as compared with HeLa and COS7 cells. The smart MSN-ss-CD/GAP delivery system holds the potential for universal therapeutic uses in both biomedical research and clinical settings.

Supramolecularly Engineered NIR-II and Upconversion Nanoparticles In Vivo Assembly and Disassembly to Improve Bioimaging

Contrast agents for bioimaging suffer from low accumulation at lesion area and high uptake in the reticuloendothelial system (RES). Assembly of nanoparticles in vivo improves their enrichment at tumors and inflamed areas. However, uncontrollable assembly also occurs at the liver and spleen owing to the uptake of nanoparticles by the RES. This is known to probably cause a higher bioimaging background and more severe health hazards, which may hamper the clinical application. Herein, a new near-infrared (NIR)-controlled supramolecular engineering strategy is developed for in vivo assembly and disassembly between lanthanide upconversion nanoparticles and second near-infrared window (NIR-II, 1000-1700 nm) nanoprobes to realize precision bioimaging of tumors. A supramolecular structure is designed to realize assembly via host-guest interactions of azobenzene and β-cyclodextrin to enhance the retention of NIR-II nanoprobes in the tumor area. Meanwhile NIR-laser-controllable nanoprobes disassembly brings about a reduction in the bioimaging background as well as acceleration of their RES clearance rate. This strategy may also be used in other nano-to-micro-scale contrast agents to improve bioimaging signal-to-noise ratio and reduce long-term cytotoxicity.

Rufloxacin Eyedrops: Effect of Different Formulations on Ocular Pharmacokinetics in Rabbits

PURPOSE

To evaluate the aqueous humor pharmacokinetics of rufloxacin in rabbits after topical administration of different formulations, and to individuate the ones showing the best pharmacokinetic profile.

METHODS

Six formulations were instilled in rabbit eyes: two pH 7.2 suspensions of non-salified rufloxacin base, or zwitterion (RUF), one of which was viscosized with tamarind seed polysaccharide (TSP); two pH 7.2 solutions of RUF obtained using hydroxypropyl-beta-cyclodextrin (CD), one of which was viscosized with TSP; and two pH 5.0 solutions of rufloxacin hydrochloride (RUF-HCl ), one of which was viscosized with TSP. At different times after administration, samples of aqueous humor were withdrawn and analyzed by high-pressure liquid chromatography. The main pharmacokinetic parameters of RUF in the aqueous humor produced by the different formulations were calculated and statistical differences were assessed.

RESULTS

The best results, in terms of aqueous humor bioavailability, were observed with two TSP-viscosized formulations: a solution of the hydrochloride (TSP/RUF-HCl) and a suspension of the base (TSP/RUF), followed by the non-viscosized solution of RUF-HCl. The formulations containing CD-solubilized RUF were much less effective.

CONCLUSIONS

The present data confirm the significant availability-enhancing properties of tamarind seed polysaccharide, and indicate that solubilization of RUF with hydroxypropyl-beta-cyclodextrin (CD/RUF) results in decreased drug availability with respect to standard formulations. Two of the TSP-viscosized formulations (RUF suspension and RUF-HCl solution) produced aqueous humor RUF concentrations in the range of activity against Enterobacteriaceae and Pseudomonas aeruginosa, thus warranting further studies on applications of rufloxacin in ocular therapy.

An Injectable System for Local and Sustained Release of Antimicrobial Agents in the Periodontal Pocket

Periodontitis treatments usually require local administration of antimicrobial drugs with the aim to reduce the bacterial load inside the periodontal pocket. Effective pharmaceutical treatments may require sustained local drug release for several days in the site of interest. Currently available solutions are still not able to fulfill the clinical need for high-quality treatments, mainly in terms of release profiles and patients' comfort. This work aims to fill this gap through the development of an in situ gelling system, capable to achieve controlled and sustained release of antimicrobial agents for medium-to-long-term treatments. The system is composed of micrometer-sized β-cyclodextrin-based hydrogel (bCD-Jef-MPs), featured by a strong hydrophilic character, suspended in a synthetic block-co-polymer solution (Poloxamer 407), which is capable to undergo rapid thermally induced sol-gel phase transition at body temperature. The chemical structure of bCD-Jef-MPs was confirmed by cross-correlating data from Fourier transform infrared (FTIR) spectroscopy, swelling test, and degradation kinetics. The thermally induced sol-gel phase transition is demonstrated by rheometric tests. The effectiveness of the described system to achieve sustained release of antimicrobial agents is demonstrated in vitro, using chlorhexidine digluconate as a drug model. The results achieved in this work disclose the potential of the mentioned system in effectively treating periodontitis lesions.

Efficacy and Safety Profile of Diclofenac/Cyclodextrin and Progesterone/Cyclodextrin Formulations: A Review of the Literature Data

Background

According to health technology assessment, patients deserve the best medicine. The development of drugs associated with solubility enhancers, such as cyclodextrins, represents a measure taken in order to improve the management of patients. Different drugs, such as estradiol, testosterone, dexamethasone, opioids, non-steroidal anti-inflammatories (NSAIDs; i.e. diclofenac), and progesterone are associated with cyclodextrins. Products containing the association of diclofenac/cyclodextrins are available for subcutaneous, intramuscular, and intravenous administration in doses that range from 25 to 75 mg. Medicinal products containing the association of progesterone/cyclodextrins are indicated for intramuscular and subcutaneous injection at a dose equal to 25 mg.

Objectives and Methods

The effects of cyclodextrins have been discussed in the solubility profile and permeability through biological membranes of drug molecules. A literature search was performed in order to give an overview of the pharmacokinetic characteristics, and efficacy and safety profiles of diclofenac/hydroxypropyl-β-cyclodextrin (HPβCD) and progesterone/HPβCD associations.

Results

The results of more than 20 clinical studies were reviewed. It was suggested that the new diclofenac/HPβCD formulation gives a rapid and effective response to acute pain and, furthermore, has pharmacokinetic and efficacy/safety profiles comparable to other medicinal products not containing cyclodextrins. One of the principal aspects of these new diclofenac formulations is that in lowering the dose (lower than 50 mg) the drugs could be more tolerable, especially in patients with comorbid conditions. Moreover, results of studies investigating the characteristics of progesterone and cyclodextrins showed that the new formulation (progesterone/HPβCD 25 mg solution) has the same bioavailability as other products containing progesterone. It is more rapidly absorbed and allows the achievement of peak plasma concentrations in a shorter time. Finally, the new formulation of progesterone was shown to be safe and not inferior to other products already on the market, with the exception of progesterone administered vaginally.

Conclusions

As shown by the results of clinical studies presented in this review, the newly approved medicines containing cyclodextrins have been found to be as effective and as well-tolerated as other medicinal products that do not contain cyclodextrins. Moreover, the newly approved lower dose of diclofenac associated with cyclodextrins is consistent with the European Medicines Agency recommendations reported in the revision of the Assessment Report for Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) and Cardiovascular Risk. Finally, the use of cyclodextrins led to significant increases in solubility and bioavailability of drugs, such as diclofenac and progesterone, and improvement in the efficacy and safety of these drugs.

[A preliminary study of pharmacokinetics of evodiamine hydroxypropyl-β-cyclodextrin inclusion complex]

OBJECTIVE

To compare the pharmacokinetic parameters of evodiamine hydroxypropyl-β-cyclodextrin inclusion complex and free evodiamine suspension in rats, and investigate the pharmacokinetic characteristics of evodiamine inclusion complex.

METHODS

Both water solubility and cumulative release percentage of EHD were tested with evodiamine as the control. Blood samples were collected from the venous plexus of SD rats after intravenous administration with evodiamine inclusion complex and free evodiamine at 100 mg/kg (equivalent evodiamine dose). Plasma concentrations of evodiamine were determined by high-performance liquid chromatography (HPLC), and the pharmacokinetic parameters were calculated using DAS 2.1.1.

RESULTS

The evodiamine inclusion complex showed a better water solubility (18.46±0.36 µg/mL) and a higher cumulative release percentage [(76.8±4.9)%] than free evodiamine. The pharmacokinetic parameters of evodiamine inclusion complex and free evodiamine in rats were as follows: Cmax, 252.5±12.43 vs 161.3±3.45 µg/L; T(max), 4.00±0 vs 4.07±0 h; MRT(0-∞), 8.46±0.91 vs 4.43±0.74 h; AUC(0-t), 2266.40±28.64 vs 911.92±8.53 µg·L(-1)·h(-1); AUC(0-∞), 2359.76±31.58 vs 919.16±9.73 µg·L(-1)·h(-1). The relative bioavailability of evodiamine inclusion complex was 256.73%.

CONCLUSION

Compared with free evodiamine, evodiamine inclusion complex has a higher bioavailability.

β-Cyclodextrin-Based Inclusion Complexation Bridged Biodegradable Self-Assembly Macromolecular Micelle for the Delivery of Paclitaxel

In this study, a novel adamantanamine-paclitaxel (AD-PTX) incorporated oligochitosan- carboxymethyl-β-cyclodextrin (CSO-g-CM-β-CD) self-assembly macromolecular (CSO-g-CM-β-CD@AD-PTX) micelle was successfully prepared in water through sonication. The formed molecules were characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance (NMR) spectroscopy, two-dimensional NMR, elemental analysis, and liquid chromatography-mass spectrometry, while the correspondent micelles were characterized by dynamic light scattering and transmission electron microscopy. We showed that the macromolecular micelle contained a spherical core-shell structure with a diameter of 197.1 ± 3.3 nm and zeta potential of -19.1 ± 4.3 mV. The CSO-g-CM-β-CD@AD-PTX micelle exhibited a high drug-loading efficacy up to 31.3%, as well as a critical micelle concentration of 3.4 × 10-7 M, which indicated good stability. Additionally, the in vitro release profile of the CSO-g-CM-β-CD@AD-PTX micelle demonstrated a long-term release pattern, 63.1% of AD-PTX was released from the micelle during a 30-day period. Moreover, the CSO-g-CM-β-CD@AD-PTX micelle displayed cytotoxicity at a sub-μM scale similar to PTX in U87 MG cells, and CSO-g-CM-β-CD exhibited a good safety profile by not manifesting significant toxicity at concentrations up to 100 μM. These results indicated that β-CD-based inclusion complexation resulting in biodegradable self-assembled macromolecular micelles can be utilized as nanocarrier, and may provide a promising platform for drug delivery in the future medical applications.

Effects of Two Surfactants and Beta-Cyclodextrin on Beta-Cypermethrin Degradation by Bacillus licheniformis B-1

The biodegradation efficiency of beta-cypermethrin (β-CY) is low especially at high concentrations mainly due to poor contact between this hydrophobic pesticide and microbial cells. In this study, the effects of two biodegradable surfactants (Tween-80 and Brij-35) and β-cyclodextrin (β-CD) on the growth and cell surface hydrophobicity (CSH) of Bacillus licheniformis B-1 were studied. Furthermore, their effects on the solubility, biosorption, and degradation of β-CY were investigated. The results showed that Tween-80 could slightly promote the growth of the strain while Brij-35 and β-CD exhibited little effect on its growth. The CSH of strain B-1 and the solubility of β-CY were obviously changed by using Tween-80 and Brij-35. The surfactants and β-CD could enhance β-CY biosorption and degradation by the strain, and the highest degradation was obtained in the presence of Brij-35. When the surfactant or β-CD concentration was 2.4 g/L, the degradation rate of β-CY in Brij-35, Tween-80, and β-CD treatments was 89.4%, 50.5%, and 48.1%, respectively. The half-life of β-CY by using Brij-35 was shortened by 69.1 h. Beta-CY content in the soil with both strain B-1 and Brij-35 decreased from 22.29 mg/kg to 4.41 mg/kg after incubation for 22 d. This work can provide a promising approach for the efficient degradation of pyrethroid pesticides by microorganisms.

A novel nasal powder formulation of glucagon: toxicology studies in animal models

BACKGROUND

Glucagon nasal powder (GNP), a novel intranasal formulation of glucagon being developed to treat insulin-induced severe hypoglycemia, contains synthetic glucagon (10% w/w), beta-cyclodextrin, and dodecylphosphocholine. The safety of this formulation was evaluated in four studies in animal models.

METHODS

The first study evaluated 28-day sub-chronic toxicology in rats treated intranasally with 1 and 2 mg of GNP/day (0.1 and 0.2 mg glucagon/rat/day). The second study evaluated 28-day sub-chronic toxicology in dogs administered 20 and 40 mg of formulation/dog/day (2 and 4 mg glucagon/dog/day) intranasally. A pulmonary insufflation study assessed acute toxicology following intra-tracheal administration of 0.5 mg of GNP (0.05 mg glucagon) to rats. Local tolerance to 30 mg of GNP (equivalent to 3 mg glucagon, the final dose for humans) was tested through direct administration into the eyes of rabbits.

RESULTS

There were no test article-related adverse effects on body weight and/or food consumption, ophthalmology, electrocardiography, hematology, coagulation parameters, clinical chemistry, urinalysis, or organ weights, and no macroscopic findings at necropsy in any study. In rats, direct intra-tracheal insufflation at a dose of 0.5 mg of GNP/rat (0.05 mg glucagon/rat) did not result in adverse clinical, macroscopic, or microscopic effects. In dogs, the only adverse findings following sub-chronic use were transient (<30 s) salivation and sneezing immediately post-treatment and mild to moderate reversible histological changes to the nasal mucosa. Daily dosing over 28 days in rats resulted in mild to moderate, unilateral or bilateral erosion/ulceration of the olfactory epithelium, frequently with minimal to mild, acute to sub-acute inflammation of the lamina propria at the dorsal turbinates of the nasal cavity in 2/10 males and 3/10 females in the high-dose group (0.2 mg glucagon/day). These lesions resolved completely over 14 days. Histological examination of tissues from both sub-chronic studies in dogs and rats revealed no microscopic findings. In rabbits, clinical observations noted in the GNP-treated eye and/or surrounding areas included ≥1 of the following: clear discharge, red conjunctiva, partial closure, and swelling of the peri-orbital area, which correlated with erythema and edema noted during ocular observations and grading.

DISCUSSION

The studies reported here revealed no safety concerns associated with GNP in animal models. Studies published earlier have highlighted the local safety profile of intranasally administered cyclodextrins (a component of GNP). The choline group, the phosphate group, and the saturated 12-carbon aliphatic chain that are present in the dodecylphosphocholine excipient used in GNP are all present in the phospholipids and lecithins seen ubiquitously in mammalian cell membranes and are unlikely to pose safety concerns; this notion is supported by several studies conducted by the authors that revealed no safety concerns. Taken together, these results suggest that intranasal delivery of GNP holds promise as a future rescue medication for use by caregivers to treat insulin-induced hypoglycemic episodes in patients with type 1 or type 2 diabetes.

CONCLUSION

This novel drug product is well tolerated in animal models.

[Pharmacokinetics Study on Curcumin Hydroxypropyl-β-Cyclodextrin Phospholipid Complex in Rats]

OBJECTIVE

To compare the in vivo pharmacokinetics of curcumin hydroxypropyl-β-cyclodextrin phospholipid complex, curcumin hydroxypropyl-β-cyclodextrin and curcumin phospholipid complex, and to discuss the advantage of hydroxypropyl-β-cyclodextrin phospholipid complex as carrier.

METHODS

Drawing blood after SD rats were oral administered with the above preparations and free drug at 50 mg/kg( corresponding to curcumin) , and the blood concentration were determined by HPLC.

RESULTS

The AUC0-∞ of curcumin hydroxypropyl-β-cyclodextrin phospholipid complex was(1 126. 20 ± 323. 24) g/(L . h), which was 5. 89, 1. 49 and 1. 17 times as curcumin (191. 08 ± 43. 27) µg/( L . h), curcumin phospholipid complex(754. 93 ± 55. 33) µg/(L . h), curcumin hydroxypropyl-β- cyclodextrin(961. 21 ± 253. 65) µg/(L . h).

CONCLUSION

The curcumin hydroxypropyl-β-cyclodextrin phospholipid complex has a better absorption property than curcumin phospholipid complex and curcumin hydroxypropyl-β-cyclodextrin, which is more beneficial to improve the bioavailability.

Spectroscopic characterization of both aqueous and solid-state diacerhein/hydroxypropyl-β-cyclodextrin inclusion complexes

Diacerhein, a poorly water soluble antirheumatic prodrug, was spectroscopically characterized to form inclusion complexes with hydroxypropyl-β-cyclodextrin (HPβCD) in both aqueous solution and in solid phase. Complexation with the hydrophilic carriers was used to improve the solubility and dissolution rate of the compound. The kinetics of the prodrug degradation to the active rhein in aqueous buffer solution were also investigated as a function of HPβCD concentration. The solid complexes prepared by different methods such as physical mixture, kneading, co-evaporation method and freeze dried method in 1:1M ratio, were characterized by DSC and FTIR. The dissolution profiles of solid complexes were determined and compared with diacerhein alone and their physical mixture, in the simulated intestinal fluid at 37°C. The accurate molecular spectroscopic characterization of diacerhein in the presence of different amounts of aqueous cyclodextrins was essential to determine the correct binding constants for the diacerhein/HPβCD system. The binding constants were also validated by UV spectrometry and HPLC procedure in order to compare the values from the different methods. Higuchi-Connors phase solubility method has proved not suitable when either the free or/and the complexed prodrug degrade in aqueous solution.

Complexation of albendazole with hydroxypropyl-β-cyclodextrin significantly improves its pharmacokinetic profile, cell cytotoxicity and antitumor efficacy in nude mice

BACKGROUND

Albendazole (ABZ) is a microtubule depolymerizing agent with a remarkable activity against a variety of tumor cells in vitro and in vivo. However, the lack of water solubility limits its application. Therefore, the aim of this study was to formulate ABZ with acetic acid/2-hydroxypropyl-β-cyclodextrin (HPβCD) with the view of improving its aqueous solubility and therefore, its antitumor efficacy.

MATERIALS AND METHODS

ABZ was dissolved in acetic acid and 25% HPβCD (w/v). Mice received a single dose of ABZ/HPβCD or a conventional suspension in hydroxypropyl methyl cellulose (HPMC) over 24 h and the concentration of ABZ and its metabolites in plasma were measured by HPLC. The antitumor efficacy of the two formulations were then evaluated and compared in nude mice bearing HCT-116 colorectal cancer xenografts.

RESULTS

Ionization with acetic acid together with complexation with hydroxylpropyl-β-cyclodextrin (HPβCD) dramatically improved the solubility of ABZ. The area under the curve (AUC) of ABZ and its active metabolite, ABZ sulfoxide (ABZSO) were approximately 2.3- and 7.3-folds higher in mice that received ABZ/HPβCD in comparison with animals that were treated with ABZ/HPMC. Additionally, the peak plasma concentration (C(max)) of ABZSO was nearly 18-times higher in mice that received ABZ/HPβCD. Furthermore, a significant delay in tumor growth that led to longer survival in mice was observed in the ABZ/HPβCD-treated group as compared to the ABZ/HPMC group.

CONCLUSION

These findings demonstrate that the combination of acetic acid and HPβCD significantly improves the solubility, pharmacokinetic profile and antitumor efficacy of ABZ. This newly-developed formulation of ABZ may be suitable for parenteral administration.

Enhancing effect of hydroxypropyl-β-cyclodextrin on the intestinal absorption process of genipin

The purpose of this work is to investigate the effect of the genipin/hydroxypropyl-β-cyclodextrin (HP-β-CD) inclusion complex on the intestinal absorption of genipin and identify its mechanism of action. The phase solubility profile was classified as A(L) type, indicating the formulation of a 1:1 stoichiometry inclusion complex. Fourier transform infrared spectroscopy, Differential scanning calorimetry, X-ray powder diffractometry, and (1)H nuclear magnetic resonance (NMR) and two-dimensional (2D) (1)H rotating-frame Overhauser enhancement (ROESY) NMR spectroscopies further confirmed the formulation of the inclusion complex with superior dissolution properties than the drug alone. The results of single-pass intestinal perfusion showed that the intestinal absorption of genipin was affected by P-glycoprotein (Pgp). The absorption rate and permeability value of the inclusion complex were significantly higher than the free drug, suggesting that its enhancing effect was involved in its solubilizing effect and Pgp inhibitory effect. The mechanisms of HP-β-CD on Pgp inhibition were demonstrated by restraining the Pgp ATPase activity rather than changing the fluidity of the cell membrane.

A study of the interaction between rhodamine 6g and hydroxy propyl β-cyclodextrin by steady state fluorescence

The binding of rhodamine 6G and hydroxy propyl β-cyclodextrin (Hβ-CD) was investigated measuring fluorescence and absorption at pH 7.0. The solid inclusion complex of Rh6G and Hβ-CD has been studied by Ultraviolet (UV) spectroscopy, Fluorimetry, Fourier Transform Infrared (FTIR), (1)H Nuclear Magnetic Resonance ((1)HNMR) and in the Scanning Electron Microscope (SEM). Association constant K(g) and K(e) were determined by the enhancement of the fluorescence of rhodamine 6G in the presence of Hβ-CD. Fluorescence of Rh6G is generally enhanced, in complexes of Rh6G and β-Cyclodextrin in aqueous solutions. The free energy change for the ground state (ΔG(g)) and for the excited state (ΔG(e)) have also been determined. The experimental results indicated that the inclusion process is an exothermic and spontaneous.

[Biological activity of water-soluble nanostructures of dihydroquercetin with cyclodextrins]

The biological properties of dihydroquercetin (DHO) modified by including it into the ring of beta-cyclodextrin (beta-CD) to give it more water-soluble properties have been investigated. It was shown that the peroral administration of the DHQ/beta-CD complex provides a long increase of DHQ concentration in rat blood (up to 7.5 h), and, unlike pure DHQ, the complex does not accumulate in the liver. As DHQ is released from the complex, it penetrates into liposome membranes, changing their thermodynamic characteristics. DHQ decreases the specific heat absorption, enthalpies, and temperature maximum of lipid melting and increases the transition half-width. This property is used to estimate the stability of the DHQ/beta-CD complex. It was shown that complex DHQ/beta-CD is not stable, and DHQ molecules slowly leave the complex in water environment. Seven and a half hours after the peroral injection of drugs, DHQ was found in the blood plasma of rats to which water-soluble complex DHQ/betaCD was injected and in the liver of rats to which free DHQ was injected. Thus, DHQ/betaCD not only is a more water-soluble complex but also it slowly releases DHQ, supporting long a low concentration of the free form of DHQ and providing the penetration of DHQ into the blood stream. After several weeks of feeding old mice with antioxidants, the activity of mitochondrial enzymes was restored to the level observed in young animals.

β-cyclodextrin cross-linked polymer as solid-phase extraction material coupled with the spectrophotometric method for the analysis of serum albumin

The β-cyclodextrin cross-linked polymer (β-CDCP) was synthesized and used as solid-phase extraction material to preconcentrate/analysis bovine serum albumin (BSA) coupled with UV-vis spectroscopy. The method based on the complex (BSA-phenylfluorone (PF)) adsorbed on β-CDCP. Adsorption kinetics and various factors of the formation procedure of BSA-PF and its retention on β-CDCP were investigated. The linear range and detection limit (DL) was 20.0-200.0 and 0.03 mg/L, respectively. Moreover, the β-CDCP could be used repeatedly. The proposed method has been applied to analysis serum albumin with satisfactory results.

Two novel ternary albendazole-cyclodextrin-polymer systems: dissolution, bioavailability and efficacy against Taenia crassiceps cysts

The effect of two water-soluble polymers: pectin and polyvinylpyrrolidone in combination with beta-cyclodextrin, on the dissolution, bioavailability and cysticidal efficacy of albendazole was evaluated using a commercial suspension as reference product. The dissolution of the albendazole-beta-cyclodextrin-pectin formulation was slow and incomplete (44.7%). No statistical differences in C(max) and AUC were found between this formulation and the reference. Also its cysticidal efficacy (33%) was similar to the reference (38%). The albendazole-beta-cyclodextrin-polyvinylpyrrolidone formulation exhibited the highest dissolution rate (78.5%) and its bioavailability was also significantly increased (2.3-fold). In addition, the cysticidal activity of this formulation (83%) was greater than a commercial suspension. Our results suggest that the ternary system of albendazole-beta-cyclodextrin-polyvinylpyrrolidone could be a potential alternative for the treatment of systemic helmintic diseases and it is worth to continue its preclinical evaluation.

[The nasal mucosa permeability and toxicity of baicalin carrier systems liposomes, beta-cyclodextrin inclusion compound, and phospholipid complex]

To increase drug concentration in the head through intranasal administration, we have investigated the excised animal nasal mucosa permeability and nasal toxicity of the baicalin drug carrier systems, such as baicalin liposomes, beta-cyclodextrin inclusion compound, and phospholipid complex. A transport of baicalin drug carrier systems through nasal mucosa was simulated in diffusion chamber in vitro, and swine, caprine and rabbit nasal mucosa was used, the concentration of drug in the receptor was determined by HPLC. By taking the apparent permeability coefficients as evaluation standard, investigated the isolated animal nasal mucosa permeability of different baicalin drug systems was investigated for screening the best baicalin drug carrier system through nasal cavity administration. Toxicity of baicalin and its phospholipids complex on toad palate mucosal cilia movement and rats nasal mucosa long-term toxicity were studied in vivo. The apparent permeability coefficient of three kinds of baicalin drug carrier systems was better than that of baicalin (P < 0.05), and its lag-time was obviously shortened. At the same time, the apparent permeability coefficient of phospholipid complex was higher than those of other two drug carrier systems (P < 0.05). The results showed that the baicalin phospholipids complex nasal mucosa permeability was obviously superior to the other two drug systems. Baicalin phospholipids complex had no toxicity to ciliary movement, and had no irritation to rat nasal mucosa. The results show that baicalin phospholipid complex was the best baicalin drug carrier system, it could significantly enhance the permeability of baicalin across nasal mucosa, had no toxicity to nasal mucosa, and could be used for intranasal administration.

Voltammetric and spectroscopic studies on binding of antitumor Morin, Morin-Cu complex and Morin-beta-cyclodextrin with DNA

A systematic comparative study of the binding of antitumor Morin and its complexes with DNA has been investigated in the Britton-Robison (BR) buffer solutions using voltammetric and spectroscopic methods. The results show that Morin molecule, acting as an intercalator, is inserted into the cavity of the beta-cyclodextrin (beta-CD) as well as into the base stacking domain of the DNA double helix. The interaction of Morin-Cu complex or the inclusion complex of Morin-beta-CD with ds-DNA causes hypochromism in the absorption spectra, along with pronounced changes in the electrochemical behavior of the Morin complexes. An isobestic point and a new spectrum band appeared indicating the formation of the new system of Morin-Cu-DNA at lambda(m)=391 nm and Morin-beta-CD-DNA at lambda(m)=375 nm. The intercalation of Morin-Cu and Morin-beta-CD complexes with DNA produces an electrochemically inactive supramolecular complex. The binding constants were calculated from the increase of the solubility, the strong hypochromism, and the decrease in peak current of Morin and its complexes upon the addition of the host molecules. Calculation of the thermodynamic parameters of the interaction of the inclusion complex of Morin-beta-CD with DNA, including Gibbs free energy change, Helmholz free energy and entropy change shows that the complexation is a spontaneous process of association.

Nonexhaustive beta-cyclodextrin extraction as a chemical tool to estimate bioavailability of hydrophobic pesticides for earthworms

Chemical methods to assess bioavailability in soil and sediment often use synthetic polymers that mimic uptake of organic compounds in organisms or microbial degradation. In this paper we have assessed a biomimetic extraction method using hydroxyl-beta-cyclodextrin (HP-beta-CD) to estimate uptake of the two insecticides alpha-cypermethrin (alpha-CYP) and chlorfenvinphos (CFVP) in the earthworm Eisenia fetida. Additionally, a novel approach was developed to estimate the efficiency of biomimetic extractions. The study revealed that HP-beta-CD is a suitable surrogate for estimating the bioaccessibility of hydrophobic chemicals in soil. If one uses a 3.5 times higher amount of HP-beta-CD than soil, effective and reproducible extractions can be achieved within 48 h. Atthese conditions, inclusion of dissolved chemicals by HP-beta-CD mimics uptake of a given compound into earthworms and takes into account sorption-related aspects that control biological uptake. The data indicate that, with increasing hydrophobicity, the affinity of organic chemicals to HP-beta-CD does not increase to the same degree as to soil organic matter. Therefore, a high surplus of HP-beta-CD is necessaryto provide a sufficient extraction capacity in biomimetic extractions.

Multivesicular Liposomes Bearing Celecoxib-β-Cyclodextrin Complex for Transdermal Delivery

In our work depot delivery systems of celecoxib were developed using multivesicular liposomes. Moreover, the solubility of celecoxib was enhanced by complexing drug with cyclodextrin to overcome the limitation of conventional therapy. The multivesicular liposomes (MVLs) bearing celecoxib-beta -cyclodextrin inclusion complex were prepared by reverse phase evaporation method, and multilamellar vesicles (MLVs)-bearing drug complex was prepared by the cast film method. The formulations were characterized for vesicle size, encapsulation efficiency, and in vitro drug release. In vivo performance of multivesicular liposomes bearing celecoxib-beta -cyclodextrin inclusion complex was evaluated by assessing anti-inflammatory activity using carrageenan-induced rat paw edema volume method. The results were compared with that of celecoxib-cyclodextrin complex and MLVs containing celecoxib-beta -cyclodextrin inclusion complex in equal amounts. Phase solubility studies for the celecoxib-beta -cyclodextrin inclusion complex clearly indicated an increase in aqueous solubility of celecoxib with an increase in beta -CD concentration. The in vitro release studies reveal that MLVs release more than 80% drug within 48 hr whereas MVL formulations release nearly the same amount of drug in 120 hr. In vivo data reveal that reduction in paw volume with MVL formulation was not rapid and fast, but the effect was maintained for prolonged periods, and even after 24 hr there was 40.7 +/- 3.40% reduction in paw volume. MVL formulation showed more sustained and prolonged anti-inflammatory effect compared with plain drug and MLVs. We concluded that multivesicular liposome can be successfully utilized for the sustained delivery of celecoxib.

Bioavailability Enhancement of Poorly Water Soluble and Weakly Acidic New Chemical Entity with 2-Hydroxy Propyl-β-Cyclodextrin: Selection of Meglumine, a Polyhydroxy Base, as a Novel Ternary Component

The purpose of the present study was to investigate the influence of a polyhydroxy base, N-acetyl glucamine (also know as Meglumine), as a ternary component on the complexation of DRF-4367, a poorly water-soluble and weakly acidic anti-inflammatory molecule, with 2-hydroxypropyl-beta-cyclodextrin (HPbetaCD). The molecular inclusion of DRF-4367 with HPbetaCD alone and in combination with ternary component was aimed at improvement in solubility and, subsequently, dissolution rate-limited oral bioavailability. The solid complexes of DRF-4367 and HPbetaCD with or without meglumine (binary and ternary systems, respectively) were prepared as coevaporated product in different stoichiometric ratios and compared against physical mixture. The formation of inclusion complexes was confirmed by using classical instrumental techniques. Phase solubility studies suggested that meglumine was responsible for solubility improvement via multiple factors rather than just providing a favorable pH. Mechanisms and factors governing solubility enhancement were investigated by using phase solubility and thermodynamic parameters. The complexation of DRF-4367 with HPbetaCD is thermodynamically favored because the Gibbs free energies of transfer of the drug to the cyclodextrin cavity are negative. The solubilization efficiency and stability were further improved while retaining the favorable Gibbs free energies of transfer with the addition of meglumine. Inclusion ternary complex of DRF-4367 with HPbetaCD and meglumine showed significant improvement in dissolution compared with uncomplexed drug and binary system. Moreover, the phenomena of reprecipitation observed with binary system during dissolution could be avoided with meglumine as an enabling ternary component. This improved physicochemical behavior of ternary complex with the novel inclusion of a polyhydroxy base translated into an enhanced oral bioavailability of DRF-4367 compared with either uncomplexed drug or nanosuspension.

Formulation Studies and In Vivo Evaluation of a Flurbiprofen-Hydroxypropyl β-Cyclodextrin System

The purpose of this study was 1) to investigate in vivo advantages of a flurbiprofen (FPN)-hydroxypropyl beta-cyclodextrin (HPbetaCD) solid dispersion (SD) in rats, 2) to study factors affecting the drug release from SD formulations, and 3) to evaluate the pharmacokinetic profile of the drug when administered as SD, in humans. The solubility of FPN in water and dissolution media was evaluated as a function of HPbetaCD concentration. The SD was prepared by coevaporation from dilute aqueous NH3 and evaluated in rats. The release of the drug from tablet formulations and capsules of SD was studied in simulated gastric fluid and phosphate buffer, pH 7.2. The bioavailability of drug when administered as SD was evaluated in humans. HPbetaCD enhanced the solubility of the drug, and SD improved bioavailability and reduced ulcerogenicity of the drug in rats. The type of excipient used affected drug release from tablets. Presence of microcrystalline cellulose, a hydrophilic polymeric excipient, resulted in uptake of water and stabilization of the resulting gels-like structure of HPbetaCD-containing tablets. This adversely affected drug release. The release from capsules filled with SD was comparable to that obtained from plain SD powder. The drug-HPbetaCD association constant in water was much lower than the values reported in literature. The bioavailability (which could suffer in case of higher association constant) was enhanced on administration of SD-filled capsules to humans.

[Preparation of coated tablets of glycyrrhetic acid-HP-beta-cyclodextrin tablets for colon-specific release]

OBJECTIVE

To prepare coated tablets of glycyrrhetinic acid and hydroxypropyl-beta-cyclodextrin (GTA-HP-beta-CYD) inclusion complex tablets for colon-specific release.

METHOD

In order to improve the solubility of GTA, the GTA-HP-beta-CYD inclusion complex was prepared by ultrasonic-lyophilization technique and its formation were characterized by X-ray powder diffraction profiles and infrared spectrometry. The effects of inclusion condition on the inclusion efficiency and stability coefficient of inclusion complex were investigated, respectively. After prepared GTA-HP-beta-CYD tablets by powder direct compression, the pH dependant polymer Eudragit III and/or mixed with Eudragit II were used for further coating materials in fluid-bed coater. The influences of coating weight on the GTA release in different pH conditions were evaluated to establish the method for prepering colon specific delivery tablets with pulsed release properties.

RESULT

The formation of inclusion complexes were proved by X-ray powder diffraction profile and phase solubility curve. The effect of pH value of solvent was played critical role on the preparation of GTA- HP-beta-CYD inclusion complex. And the inclusion efficiency of GTA was 9. 3% and the solubility was increased to 54. 6 times at optimized method. The Eudragit III coated GTA- HP-beta-CYD tablets with coating weight 10% and 16% were showed pH dependant colon specific release profiles with slow release rate. The release profile of tablets coated with the mixture of Eudragit II and Eudragit III (1:2) were indicated typical pH dependant colon specific and pulsed release properties while the coating weight was 17%.

CONCLUSION

The preliminary method for preparation of colon specific release tablets containing glycyrrhetinic acid with improved solubility was established for further in vivo therapeutic experiment.

Biodistribution of intravenously administered amphiphilic β-cyclodextrin nanospheres

Amphiphilic beta-cyclodextrin (betaCDa) nanospheres (mean diameter 90-110 nm) prepared by the solvent displacement method were developed as a colloidal drug delivery system. In order to survey the fate of these nanoparticles, the amphiphilic beta-cyclodextrin was first iodinated by a two-step procedure involving iodination of the primary face followed by an acylation of the secondary face. After radiolabeling of this derivative with (125)I, nanospheres made of betaCDa/betaCDa (125)I were formulated. After a single intravenous injection of labeled nanoparticles in mice, the organ distribution was analyzed from 10 min to 6 days. A rapid clearance of (125)I-labeled betaCDa nanospheres from the blood circulation to the mononuclear phagocyte system was visualized by non-invasive planar imaging study. Radioactivity measurements in organs showed that the nanospheres mainly concentrated in the liver and the spleen where 28 and 24% of the radioactivity per gram of organ was, respectively, found 10 min after injection. At the opposite, the blood activity was low at that time and become negligible thereafter. Finally, the fact that no particular sign of toxicity is observed in injected animals should be emphasized since it is the first report on intravenous administration of betaCDa nanoparticles.

Pharmacokinetics of itraconazole after intravenous and oral dosing of itraconazole‐cyclodextrin formulations

The current research evaluated and compared the efficacy of hydroxybutenyl-beta-cyclodextrin (HBenBCD) and hydroxypropyl-beta-cyclodextrin (HPBCD) as enhancers of itraconazole solubility and oral bioavailability. At 10 wt% cyclodextrin, 17-fold and 3.8-fold increases in itraconazole aqueous solubility were observed in the presence of HBenBCD and HPBCD, respectively. Significant differences in the dissolution of itraconazole in the presence of these two cyclodextrins were also observed. Itraconazole pharmacokinetics is known to exhibit a significant food effect. However, testing in biorelevant media indicated that no food effects should be observed after oral administration of itraconazole:HBenBCD complexes. Formulations of itraconazole with HBenBCD were prepared and these complexes, along with the commercial forms of itraconazole with and without HPBCD (Sporanox) were administered to male Sprague-Dawley rats by oral and intravenous routes. Intravenous administration of itraconazole formulated with HBenBCD resulted in a higher AUC relative to Sporanox. When administered as oral solutions, the itraconazole:HBenBCD formulation provided higher oral bioavailability than the Sporanox oral solution. When administered as solid formulations, the itraconazole:HBenBCD solid formulation provided a 2x increase in oral bioavailability relative to the Sporanox solid formulation. No food effects were observed with the itraconazole:HBenBCD solid dosage forms. Drug/metabolite ratios were dependent upon the dosage form.

Enhancement of dissolution amount and in vivo bioavailability of itraconazole by complexation with β-cyclodextrin using supercritical carbon dioxide

The main objective of this study was to improve the inclusion formation between itraconazole and beta-cyclodextrin and thus enhance dissolution amount and bioavailability characteristics of itraconazole. Inclusion complexes between itraconazole and beta-cyclodextrin were prepared using simple physical mixing, conventional coprecipitation method, and supercritical carbon dioxide (SC CO(2)). Effects of process variables (temperature, pressure) and drug:cyclodextrin ratio on inclusion yield and thermal behavior of the solid complexes prepared by SC CO(2) were studied and compared to those obtained by physical mixing and coprecipitation methods. In addition, dissolution amounts of the products obtained by different methods were measured in gastric fluid. Finally, pharmacokinetic studies of the inclusion complexes were conducted in male Wistar rats to assess the bioavailability of the prepared complexes. Results showed that temperature, pressure and itraconazole:beta-cyclodextrin ratio had significant effects on the inclusion yield of the complex prepared by SC CO(2) method. Higher inclusion yields were obtained in the SC CO(2) method as compared to physical mixing and coprecipitation methods. In vivo drug pharmacokinetic studies showed that the itraconazole-beta-cyclodextrin product prepared using SC CO(2) gave higher bioavailability of itraconazole (in blood, liver and kidney of male Wistar rats) as compared to the products obtained by physical mixing or coprecipitation methods.

Single-dose pharmacokinetics of intravenous itraconazole and hydroxypropyl-beta-cyclodextrin in infants, children, and adolescents

This investigation was designed to evaluate the single-dose pharmacokinetics of itraconazole, hydroxyitraconazole, and hydroxypropyl-beta-cyclodextrin (HP-beta-CD) after intravenous administration to children at risk for fungal infection. Thirty-three children aged 7 months to 17 years received a single dose of itraconazole (2.5 mg/kg in 0.1-g/kg HP-beta-CD) administered over 1 h by intravenous infusion. Plasma samples for the determination of the analytes of interest were drawn over 120 h and analyzed by high-pressure liquid chromatography, and the pharmacokinetics were determined by traditional noncompartmental analysis. Consistent with the role of CYP3A4 in the biotransformation of itraconazole, a substantial degree of variability was observed in the pharmacokinetics of this drug after IV administration. The maximum plasma concentrations (C(max)) for itraconazole, hydroxyitraconazole, and HP-beta-CD averaged 1,015 +/- 692 ng/ml, 293 +/- 133 ng/ml, and 329 +/- 200 mug/ml, respectively. The total body exposures (area under the concentration-time curve from 0 to 24 h) for itraconazole, hydroxyitraconazole, and HP-beta-CD averaged 4,922 +/- 6,784 ng.h/ml, 3,811 +/- 2,794 ng.h/ml, and 641.5 +/- 265.0 mug.h/ml, respectively, with no significant age dependence observed among the children evaluated. Similarly, there was no relationship between age and total body clearance (702.8 +/- 499.4 ml/h/kg); however, weak associations between age and the itraconazole distribution volume (r(2) = 0.18, P = 0.02), C(max) (r(2) = 0.14, P = 0.045), and terminal elimination rate (r(2) = 0.26, P < 0.01) were noted. Itraconazole infusion appeared to be well tolerated in this population with a single adverse event (stinging at the site of infusion) deemed to be related to study drug administration. Based on the findings of this investigation, it appears that intravenous itraconazole can be administered to infants beyond 6 months, children, and adolescents using a weight-normalized approach to dosing.

Investigation of enhancement of solubility of norfloxacin beta-cyclodextrin in presence of acidic solubilizing additives

The present study is aimed at improving the solubility of a poorly water-soluble drug, norfloxacin by incorporating solubilizing additives such as ascorbic acid and citric acid into the beta-cyclodextrin complexes. Norfloxacin, being amphoteric in nature, exhibits a higher solubility at pH below 4 and above 8. Addition of substances like ascorbic acid and citric acid in beta-cyclodextrin complexes reduces the pH of the immediate microenvironment of the drug below pH 4. In the present work, beta-cyclodextrin complexes of norfloxacin were prepared along with solubilizing additives such as citric acid and ascorbic acid in various proportion and the dissolution profile was performed in both HCl buffer, pH 1.2 and phosphate buffer, pH 7.4. The results have shown an enhanced dissolution rate in both media. DSC and IR spectral studies performed on the solid complexes have shown that there is no interaction of the drug with the additives and beta-cyclodextrin. Disc diffusion studies have shown larger diameters of zone of inhibition indicating a greater diffusivity of the drug into the agar medium.

Comparative Evaluation of Ibuprofen/β-Cyclodextrin Complexes Obtained by Supercritical Carbon Dioxide and Other Conventional Methods

PURPOSE

The preparation of drug/cyclodextrin complexes is a suitable method to improve the dissolution of poor soluble drugs. The efficacy of the Controlled Particle Deposition (CPD) as a new developed method to prepare these complexes in a single stage process using supercritical carbon dioxide is therefore compared with other conventional methods.

MATERIALS AND METHODS

Ibuprofen/beta-cyclodextrin complexes were prepared with different techniques and characterized using FTIR-ATR spectroscopy, powder X-ray diffractometry (PXRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). In addition, the influences of the processing technique on the drug content (HPLC) and the dissolution behavior were studied.

RESULTS

Employing the CPD-process resulted in a drug content of 2.8+/-0.22 wt.% in the carrier. The material obtained by CPD showed an improved dissolution rate of ibuprofen at pH 5 compared with the pure drug and its physical mixture with beta-cyclodextrin. In addition CPD material displays the highest dissolution (93.5+/- 2.89% after 75 min) compared to material obtained by co-precipitation (61.3 +/-0.52%) or freeze-drying (90.6 +/-2.54%).

CONCLUSION

This study presents the CPD-technique as a well suitable method to prepare a drug/beta-cyclodextrin complex with improved drug dissolution compared to the pure drug and materials obtained by other methods.

The effect of hydrophilic base on pharmaceutical availability of prednisolone complexed with beta-cyclodextrin

Studies on the effect of hydrophilic gel composition on pharmaceutical availability of prednisolone complexed with beta-cyklodextrin at P:beta-CD ratios 1:1 and 1:2 revealed that the half-release times were shortened and differentiated depending on the substances added hydrogel to propylene glycol, dimethylacetamide and polysorbate 20 in comparison to preparations containing non-complexed active substance.

Delay in ICR/f Rat Lens Opacification by the Instillation of Eye Drops Containing Disulfiram and Hydroxypropyl-.BETA.-cyclodextrin Inclusion Complex

In this study, we attempted to enhance disulfiram (DSF) solubility using a 2-hydroxypropyl-beta-cyclodextrin (HPbetaCD) and hydroxypropylmethylcellulose (HPMC). We also investigated the effect of an HPbetaCD solution containing DSF and HPMC (DSF eye drops) on cataract development in ICR/f rat. The solubility of DSF increased with increasing HPbetaCD concentration, and the solubility of DSF in HPbetaCD solution containing 0.1% HPMC was approximately 20% greater than that of DSF in HPbetaCD solution without HPMC. In in vivo transcorneal penetration experiments using rabbits, only diethyldithiocarbamate (DDC) was detected (DSF was not detected) in the aqueous humor. This DSF-DDC conversion in the cornea was inhibited by treatment with a sulfhydryl (SH) inhibitor, p-mercuribenzoate and N-ethylmaleimide, in in vitro transcorneal penetration experiments using rabbit corneas. On the other hand, the instillation of 0.25% and 0.5% DSF eye drops delayed cataract development in ICR/f rats, a recessive-type hereditary cataractous strain. The present study demonstrates that DSF in HPbetaCD solution with HPMC is converted to DDC by the catalysis of proteins containing SH residues in the cornea, and this DDC may cause the delay in cataract development in ICR/f rats.

Eudragit RS 100 microparticles containing 2-hydroxypropyl-beta-cyclodextrin and glutathione: physicochemical characterization, drug release and transport studies

The aim of this study was to encapsulate glutathione (GSH) alone or in combination with hydroxypropyl-beta-cyclodextrin (HP-beta-CD) in Eudragit RS 100 microparticles (MPs), and to evaluate these novel delivery systems for oral administration of the considered tripeptide. The MPs were prepared by an O/O emulsion-solvent evaporation method according to a multilevel experimental design involving the volume of liquid paraffin, the HP-beta-CD amount, and the drug/polymer ratio as independent variables. The effects of these parameters on particle size, entrapment efficiency, and drug release were investigated. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) analysis and differential scanning calorimetry (DSC) studies were performed to evaluate possible interactions between GSH and Eudragit RS 100 polymer and to characterize the physical state of drug within the MPs. The release profiles of GSH from MPs were examined in vitro at pH 1.2, 6.8. and 7.4 using the USP III (BioDis) dissolution apparatus. In general, a slow and zero-order release of GSH from MPs at pH 1.2 occurred, while at higher pH values considerable amounts of glutathione disulfide (i.e., GSSG) were observed. The enzymatic stability and the intestinal permeability of some GSH-containing MPs were assessed by using pepsin, alpha-chymotrypsin, gamma-glutamyl-transpeptidase and everted frog intestinal sac methodology, respectively. The results suggest that GSH-loaded Eudragit RS 100 MPs containing HP-beta-CD represent a new sustained GSH delivery system useful for the oral administration of the examined tripeptide.

Methyl-β-cyclodextrin enhances the susceptibility of human breast cancer cells to carboplatin and 5-fluorouracil: Involvement of Akt, NF-κB and Bcl-2

The response rates of extensively used chemotherapeutic drugs, carboplatin (Carb) or 5-fluorouracil (5-FU) are relatively disappointing because of considerable side effects associated with their high-dose regimen. In the present study, we determined whether treatment with a cholesterol depleting agent, methyl-beta-cyclodextrin (MCD), enhances the weak efficacy of low doses of Carb or 5-FU in human breast cancer cells. Data demonstrate that pretreatment with MCD significantly potentiates the cytotoxic activity of Carb and 5-FU in both MCF-7 and MDA-MB-231. Furthermore, we explored the molecular basis of enhanced cytotoxicity, and our data revealed that low-dose treatment with these drugs in MCD pretreated cells exhibited significantly decreased Akt phosphorylation, NF-kappaB activity and down-regulation in expression of anti-apoptotic protein Bcl-2. In addition, MCD pretreated cells demonstrated an increased intracellular drug accumulation as compared to cells treated with drugs alone. Taken together, our data provide the basis for potential therapeutic application of MCD in combination with other conventional cytotoxic drugs to facilitate reduction of drug dosage that offers a better chemotherapeutic approach with low toxicity.

Accumulation of the solvent vehicle sulphobutylether beta cyclodextrin sodium in critically ill patients treated with intravenous voriconazole under renal replacement therapy

Background

Voriconazole was introduced for the treatment of life-threatening fungal infections. The intravenous form includes the solvent vehicle sulphobutylether beta cyclodextrin sodium which shows an impaired clearance under intermittent dialysis therapy. This investigation aimed to determine first clinical data on sulphobutylether beta cyclodextrin sodium blood levels to verify the risk for accumulation.

Methods

In four patients suffering from renal insufficiency and intermittent dialysis therapy who needed a treatment with intravenous voriconazole as a reserve antifungal at the intensive care unit of the Mainz University Hospital the trough levels of voriconazole and sulphobutylether beta cyclodextrin sodium were measured.

Results

A 75-year-old woman showed a maximal sulphobutylether beta cyclodextrin sodium plasma level of 145 μg/ml in the initial phase. After a few days renal function recovered and the plasma levels came down to less than 20 μg/ml. In contrast to this patient with a recovery of renal function the remaining three patients showed renal failure during the complete period of intravenous treatment with voriconazole. In these patients an accumulation of sulphobutylether beta cyclodextrin sodium plasma levels was determined with a maximum of 523 μg/ml in a 18-year-old man, 409 μg/ml in a 57-year-old man, and 581 μg/ml in a 47-year-old man.

Conclusion

The present data indicate an accumulation of sulphobutylether beta cyclodextrin sodium in patients treated with intravenous voriconazole and dialysis therapy. Fortunately, no toxic effects were observed, although the accumulated dose values were lower but comparable with those used in previous toxicity studies with animals.

Enhanced bioavailability of a new thiazolidine derivative FPFS-410, an antidiabetic and lipid-lowering drug, after oral administration of its hydroxypropyl-β-cyclodextrin complex to bile duct-cannulated rats

The effect of bile acids on bioavailability of FPFS-410 (2-(N-Cyanoimino)-5-{(E)-4-styrylbenzylidene}-4-oxothiazolidine) after oral administration of the drug and its 2-hydroxypropyl-beta-cyclodextrin (HP-beta-CyD) complex was investigated. The complexation with HP-beta-CyD increased the oral bioavailability of FPFS-410 in normal rats in a HP-beta-CyD concentration-dependent manner, compared with that of drug alone. In bile duct-cannulated rats, bile acid concentrations in pylic serum and biliary were decreased to 18% and 14% of sham-operated rats, respectively. After oral administration of the HP-beta-CyD complex, the plasma levels of FPFS-410 were lower in bile duct-cannulated rats than in sham-operated rats up to 1 h, however, this order reversed from 2 to 12 h. The plasma levels of M1, a dominant metabolite of FPFS-410 in rats, significantly decreased until 2 h after administration of the complex in bile duct-cannulated rats, compared with in sham-operated rats. Bioconversion of FPFS-410 to M1 and CYP3A2 expression in the liver was markedly lowered by bile duct-cannulation. Bile duct-cannulation did not, however, affect the serum levels of estradiol. These results suggest that bile acids have a pivotal role for bioavailability of FPFS-410 after oral administration of the FPFS-410 complex with HP-beta-CyD through CYP3A2 activity in liver of rats.

Nasal absorption of metoclopramide from different Carbopol 981 based formulations: In vitro, ex vivo and in vivo evaluation

There is a need for nasal drug delivery of metoclopramide HCI (MTC) in specific patient populations where the use of commercially available intravenous and oral dosage forms may be inconvenient and/or unfeasible. In this perspective, nasal dosage forms (solution, gel and lyophilized powder) of MTC were prepared by using a mucoadhesive polymer Carbopol 981 (CRB 981). The drug release studies of formulations were performed by using a modified horizontal diffusion chamber with cellulose membrane and excised cattle nasal mucosa as diffusion barriers. After the ex vivo experiments, the morphological appearances of the nasal mucosa were analyzed with the light microscopic studies. In vivo experiments were carried on sheep model. The release of MTC from solution and powder formulations was found higher than gel formulation (p < 0.05) and no severe damage was found on the integrity of nasal mucosa after ex vivo experiments. The penetration enhancing effect of dimethyl-beta-cyclodextrin (DM-beta-CD) used in powder formulations was observed in ex vivo and in vivo experiments. In contrast to in vitro and ex vivo experiments the nasal bioavailability of gel formulation was found higher than those of the solution and powder (p < 0.05) and might represent a promising novel tool for the systemic delivery of MTC.

[Studies on absorptive mechanism of lipophilic components of danshen from its hydroxypropyl-beta-cyclodextrin inclusion complex]

Taking Tanshinon IIA as the target and using reversed phase high performance liquid chromatography,we have developed a rapid and sensitive assay for lipophilic components of Danshen (LCD) in perfusate. The model of intestinal absorption was used to determine the concentration of Tanshinon IIA in rats as an in situ model. The change of concentration of Tanshinon IIA was separately calculated according to Michaelis-Menten and the Fick's equation to investigate the absorptive limit step of the LCD. It was concluded that the limit step to absorption of LCD was at the dissolution, by assessing the fitting index or correlative index. On the basis of the conclusion, the experiment was designed to prepare the inclusive complex of the LCD with hydroxypropyl-beta-cyclodextrin (HP-beta-CD) and to study its absorptive mechanism. With the increase of dosage of complex, its absorption did not show saturated phenomenon in gastro-intestinal tract in rats and the constant Ka did not show significant difference, suggesting that the transport of mechanism in vivo is similar to passive transport.

Conjugates of poly(DL-lactic acid) with ethylenediamino or diethylenetriamino bridged bis(beta-cyclodextrin)s and their nanoparticles as protein delivery systems

Some biodegradable amphiphilic copolymers were synthesized by conjugating poly(DL-lactic acid) (PLA) onto ethylenediamino or diethylenetriamino bridged bis(beta-cyclodextrin)s (bis-CDs). Double emulsion (DE) and nanoprecipitation (NP) methods were used to fabricate the nanoparticles of these copolymers entrapping bovine serum albumin (BSA) as a model protein. Effects of the experimental parameters, such as copolymer composition, BSA concentration, copolymer concentration and poly(vinyl alcohol) concentration, on particular size and encapsulation efficiency (EE) were investigated. Their EE to BSA could reach 83.5% at an optimized condition owing to the cooperative binding effect of the CD moiety with BSA. The core-corona structure of copolymer micelles fabricated from the nanoprecipitation was studied on the basis of 1H NMR and other measurements at various temperatures. The results showed that the core-corona structure kept stable below 50 degrees C (lower than Tg). And increase of the micelle association number occurred above the Tg because the size of the NPs became larger and proton signals of the liquid-like PLA cores could be observed in 1H NMR in D2O at 60 degrees C. The release profiles of NPs showed a burst effect followed by a continuous release. Sodium dodecyl sulfate polyacrylamide gel electrophoresis, circular dichroic and fluorescence spectra were further used to identify the stability of BSA released from the NPs. The nanoparticles from the conjugates have a promising potential in nasal delivery system.

Sublingual administration of Delta9-tetrahydrocannabinol/beta-cyclodextrin complex increases the bioavailability of Delta9-tetrahydrocannabinol in rabbits

The bioavailability of Delta(9)-tetrahydrocannabinol (THC) was determined after its sublingual administration as solid THC/beta-cyclodextrin (THC/beta-CD) complex, and was compared to oral administration of ethanolic THC, in rabbits. The absolute bioavailability of THC after sublingual administration of solid THC/beta-CD complex powder (16.0 +/- 7.5%; mean +/- SD; n = 4) is higher than the bioavailability of THC after oral administration of ethanolic THC solution (1.3 +/- 1.4%; mean +/- SD; n = 4). The results suggest that sublingual administration of THC/beta-CD complex is a useful tool in improving absolute bioavailability of THC.

Diclofenac-beta-cyclodextrin binary systems: physicochemical characterization and in vitro dissolution and diffusion studies

The aim of this work was to study the influence of beta-cyclodextrin (beta-CD) on the biopharmaceutic properties of diclofenac (DCF). To this purpose the physicochemical characterization of diclofenac-beta-cyclodextrin binary systems was performed both in solution and solid state. Solid phase characterization was performed using differential scanning calorimetry (DSC), powder x-ray diffractometry (XRD), and Fourier transform infrared spectroscopy (FTIR). Phase solubility analyses, and in vitro permeation experiments through a synthetic membrane were performed in solution. Moreover, DCF/beta-CD interactions were studied in DMSO by 1H nuclear magnetic resonance (NMR) spectroscopy. The effects of different preparation methods and drug-to-beta-CD molar ratios were also evaluated. Phase solubility studies revealed 1:1 M complexation of DCF when the freeze-drying method was used for the preparation of the binary system. The true inclusion for the freeze-dried binary system was confirmed by 1H NMR spectroscopy, DSC, powder XRD, and IR studies. The dissolution study revealed that the drug dissolution rate was improved by the presence of CDs and the highest and promptest release was obtained with the freeze-dried binary system. Diffusion experiments through a silicone membrane showed that DCF diffusion was higher from the saturated drug solution (control) than the freeze-dried inclusion complexes, prepared using different DCF-beta-CD molar ratios. However, the presence of the inclusion complex was able to stabilize the system giving rise to a more regular diffusion profile.

Enhancement of the release of azelaic acid through the synthetic membranes by inclusion complex formation with hydroxypropyl-beta-cyclodextrin

The aim of this study was to investigate the release rates of azelaic acid and azelaic acid-hydroxypropyl-beta-cyclodextrin (HPbetaCD) inclusion complex through three types of synthetic membranes, namely cellophane, silicone and elastomer membranes. Solid inclusion complexes of azelaic acid-HPbetaCD at the molar ratio of 1:1 were prepared by coevaporation and freeze-drying methods, subsequently characterized by differential scanning calorimetry, X-ray diffractometry and dissolution studies. Solid inclusion complex obtained by coevaporation method which exhibited the inclusion of azelaic acid in the HPbetaCD cavity and gave the highest dissolution rate of azelaic acid was selected for the release study. Release studies of azelaic acid and this complex through the synthetic membranes were conducted using vertical Franz diffusion cells at 30 degrees C for 6 days. The release rates of azelaic acid through the synthetic membranes were enhanced by the formation of inclusion complex with HPbetaCD at the molar ratio of 1:1, with the increasing fluxes of about 41, 81 and 28 times of the uncomplexed system in cellophane, silicone and elastomer membranes, respectively. The result from this study can be applied for the development of azelaic acid for topical use.

Preparation of celecoxib-dimethyl-β-cyclodextrin inclusion complex: characterization and in vitro permeation study

The ability of 2,6-di-O-methyl-beta-cyclodextrin (DM-beta-Cyd) to include the anti-inflammatory drug celecoxib (CCB) was evaluated. The complex was prepared by kneading and freeze-drying methods and was characterized in the solid state and in aqueous solution. Water solubility and dissolution rate of CCB, in a medium simulating gastric fluid, significantly increased after complexation, with complete dissolution obtained after 30 and 180 min for the freeze-dried and kneaded complexes respectively. Phase solubility studies showed Ap-type diagrams. Stability constants for the 1:1 and 1:2 CCB-DM-beta-Cyd complexes and (1)H-NMR studies suggested a probable 1:1 inclusion complex and only an external interaction for the second Cyd molecule. Thermodynamic parameters of the binding process showed the existence of van der Waals forces between CCB and DM-beta-Cyd. DM-beta-Cyd influenced the permeation of CCB through the CaCo-2 cells monolayer. The increase of permeation observed was due to the fast dissolution rate of the included drug and to a destabilizing action exerted by the macrocycle on the biomembrane.

[Pharmacokinetics of breviscapine and its beta-cyclodextrin complex in rats]

AIM

To establish RP-HPLC method for determination of plasma scutellarin concentration and study of the pharmacokinetic behavior of scutellarin in rat after ig administration of breviscapine and its beta-cyclodextrin complex (breviscapine-beta-CD).

METHODS

Mobile phase composed of methanol and acetate buffer. The column was Shim-pack C18. Twelve rats randomized into 2 groups were separately given breviscapine and breviscapine-beta-CD at single dose of 10.8 mg.kg(-1). Drug in plasma was extracted and determined by HPLC. The pharmacokinetic parameters were calculated by 3P97 software.

RESULTS

Linearity was obtained over the range of 10-400 ng.mL(-1). The recovery was 95.32%-98.81%. C(max) and AUC(0-12 h) of breviscapine were (154 +/- 18) ng.mL(-1) and (710 +/- 126) ng.h.mL(-1). For breviscapine-beta-CD, C(max) and AUC(0-12 h) were (328 +/- 31) ng.mL(-1) and (1,093 +/- 200) ng.h.mL(-1), respectively. There were significant differences of AUC(0-12 h) between breviscapine and breviscapine-beta-CD (P < 0.01).

CONCLUSION

The assay method was suitable for the determination of scutellarin plasma concentration in rat. Brevescapine-beta-CD showed greater absorption compared with that of brevescapine.

Nasal insulin delivery in the chitosan solution: in vitro and in vivo studies

The effects of chitosan concentrations, osmolarity, medium and absorption enhancers in the chitosan solution on nasal insulin delivery were studied in vitro and in vivo. The penetration of insulin through the mucosa of rabbit nasal septum was investigated by measuring the transmucosal flux in vitro, while the nasal absorption of insulin in vivo was assessed by the efficiency in lowering the blood glucose levels in normal rats. It was demonstrated that increasing concentrations of chitosan up to 1.5% (w/v) caused an increase in the permeability of insulin across the nasal mucosa. Insulin given intranasally in hypo- or hyperosmotic formulation showed a higher hypoglycemic effect than insulin delivered in isoosmotic formulation. Insulin formulation in chitosan solution prepared with deionized water brought to a higher relative pharmacological bioavailability (Fr) value than that prepared with 50 mM pH 7.4 phosphate buffer. A formulation containing both 1% chitosan and 0.1% ethylenediaminetetraacetic acid (EDTA), 5% polysorbate 80 (Tween 80) or 1.2% beta-cyclodextrin (beta-CD) did not lead to a higher Fr than insulin formulated with 1% chitosan alone. The formulation containing both 5% hydroxypropyl-beta-cyclodextrin (HP-beta-CD) and 1% chitosan was more effective at reducing blood glucose levels than the formulation containing 5% HP-beta-CD or 1% chitosan alone. The studies indicated that chitosan concentrations, osmolarity, medium and absorption enhancers in chitosan solution have significant effect on the insulin nasal delivery. The results of in vitro experiments were in good agreement with that of in vivo studies.

Applicability of (SBE)7m-beta-CD in controlled-porosity osmotic pump tablets (OPTs)

The purpose of this study was to investigate the general application of a controlled-porosity osmotic pump tablet (OPT) utilizing (SBE)7m-beta-CD as both a solubilizer and an osmotic agent for drugs with varying physical properties. OPTs utilizing (SBE)7m-beta-CD were prepared for five poorly soluble and two highly water-soluble drugs. The Japanese Pharmacopoeia dissolution method was used to study the drug and (SBE)7m-beta-CD release from the OPTs. The drug concentration in the OPT core after the OPT was placed in the release medium for two hours was assayed gravimetrically and by HPLC. An appropriate composition ratio (ACR) of (SBE)7m-beta-CD to drug at which drug release from the OPT was complete and pH-independent within the physiological pH range of the GI tract was determined for each drug. The ACR values correlate to the drug concentration in the OPT core when the OPTs were placed in the release medium for two hours. The release profiles of prednisolone (a poorly water-soluble drug) and sodium chloride (a water-soluble compound) from the OPTs were almost the same as that of (SBE)7m-beta-CD. Also, the release rate of each drug per unit membrane surface area from the OPTs was similar, regardless of the differences in drug solubility. The present results confirmed that (SBE)7m-beta-CD serves as both a solubility modulator and as an osmotic pumping agent for OPTs, from which the release rate of both water-soluble and poorly water-soluble drugs can be controlled.

2-Hydroxypropyl-beta-cyclodextrin (HP-beta-CD): a toxicology review

2-Hydroxylpropyl-beta-cyclodextrin (HP-beta-CD) is an alternative to alpha-, beta- and gamma-cyclodextrin, with improved water solubility and may be more toxicologically benign. This paper reviews the toxicity of HP-beta-CD, using both literature information and novel data, and presents new information. In addition, it includes a brief review from studies of the metabolism and pharmacokinetics of HP-beta-CD in both humans and animals. This review concludes that HP-beta-CD is well tolerated in the animal species tested (rats, mice and dogs), particularly when dosed orally, and shows only limited toxicity. In short duration studies, there were slight biochemical changes whereas studies of a longer duration, up to three months, produced additional minor haematological changes but no histopathological changes. When dosed intravenously, histopathological changes were seen in the lungs, liver and kidney but all findings were reversible and no effect levels were achieved. The carcinogenicity studies showed an increase in tumours in rats in the pancreas and intestines which are both considered to be rat-specific. There were also non-carcinogenic changes noted in the urinary tract, but these changes were also reversible and did not impair renal function. There were no effects on embryo-foetal development in either rats or rabbits. HP-beta-CD has been shown to be well tolerated in humans, with the main adverse event being diarrhoea and there have been no adverse events on kidney function, documented to date.

Solid-state characterization and dissolution properties of Naproxen–Arginine–Hydroxypropyl-β-cyclodextrin ternary system

The effect of ternary complexation of naproxen, a poorly water soluble anti-inflammatory drug, with hydroxypropyl-beta-cyclodextrin and the basic aminoacid L-arginine on the drug dissolution properties has been investigated. Equimolar binary (drug-cyclodextrin or drug-arginine) and ternary (drug-cyclodextrin-arginine) systems were prepared by blending, cogrinding, coevaporation, and characterized by differential scanning calorimetry, thermogravimetric analysis, FT-IR spectroscopy, X-ray diffractometry. The dissolution behavior of naproxen from the different products was evaluated by means of a continuous flow through method. The results of solid state studies indicated the presence of strong interactions between the components in ternary coevaporated and coground systems, which were both of totally amorphous nature. In contrast, the presence of either free drug or free arginine was detected when the third component (cyclodextrin or aminoacid) was physically mixed, respectively, to the drug-arginine binary system (as physical mixture, coevaporate, or coground product) or to the drug-cyclodextrin binary system (as physical mixture, coevaporate, or coground product). All ternary combinations were significantly (P<0.001) more effective than the corresponding binary drug-cyclodextrin and drug-arginine systems in improving the naproxen dissolution rate. The best performance in this respect was given by the ternary coevaporate, with about 15 times increase in terms of both drug relative dissolution rate and dissolution efficiency. The synergistic effect of the simultaneous use of arginine and cyclodextrin on the dissolution rate of naproxen was attributed to the combined effects of inclusion in cyclodextrin and salt formation, as well as to a specific role played by arginine in this interaction.