Development of α-Cyclodextrin-Based Orally Disintegrating Tablets for 4-Phenylbutyrate.

Despite major improvements brought about by the introduction of taste-masked formulations of 4-phenylbutyrate (PB), poor compliance remains a significant drawback to treatment for some pediatric and dysphagic patients with urea cycle disorders (UCDs). This study reports on the development of a cyclodextrin (CD)-based orally disintegrating tablet (ODT) formulation for PB as an alternative to existing formulations. This is based on previous reports of the PB taste-masking potential of CDs and the suitability of ODTs for improving compliance in pediatric and dysphagic populations. In preliminary studies, the interactions of PB with α and ßCD in the solid state were characterized using X-ray diffraction, scanning electron microscopy, dissolution, and accelerated stability studies. Based on these studies, lyophilized PB-CD solid systems were formulated into ODTs after wet granulation. Evaluation of the ODTs showed that they had adequate physical characteristics, including hardness and friability and good storage stability. Notably, the developed αCD-based ODT for PB had a disintegration time of 28 s and achieved a slightly acidic and agreeable pH (≈5.5) in solution, which is suitable for effective PB-CD complexation and taste masking. The developed formulation could be helpful as an alternative to existing PB formulations, especially for pediatric and dysphagic UCD patients.

Study of the Structural Chemistry of the Inclusion Complexation of 4-Phenylbutyrate and Related Compounds with Cyclodextrins in Solution: Differences in Inclusion Mode with Cavity Size Dependency.

4-phenylbutyrate (PB) and structurally related compounds hold promise for treating many diseases, including cancers. However, pharmaceutical limitations, such as an unpleasant taste or poor aqueous solubility, impede their evaluation and clinical use. This study explores cyclodextrin (CD) complexation as a strategy to address these limitations. The structural chemistry of the CD complexes of these compounds was analyzed using phase solubility, nuclear magnetic resonance (NMR) spectroscopic techniques, and molecular modeling to inform the choice of CD for such application. The study revealed that PB and its shorter-chain derivative form 1:1 αCD complexes, while the longer-chain derivatives form 1:2 (guest:host) complexes. αCD includes the alkyl chain of the shorter-chain compounds, depositing the phenyl ring around its secondary rim, whereas two αCD molecules sandwich the phenyl ring in a secondary-to-secondary rim orientation for the longer-chain derivatives. ßCD includes each compound to form 1:1 complexes, with their alkyl chains bent to varying degrees within the CD cavity. γCD includes two molecules of each compound to form 2:1 complexes, with both parallel and antiparallel orientations plausible. The study found that αCD is more suitable for overcoming the pharmaceutical drawbacks of PB and its shorter-chain derivative, while ßCD is better for the longer-chain derivatives.

Study of the inclusion complexes formed between 4-phenylbutyrate and α-, ß- and γ-cyclodextrin in solution and evaluation on their taste-masking properties.

OBJECTIVES: 4-Phenylbutyrate (PB), which is used in the management of urea cycle disorders, has an unpleasant taste leading to poor patient compliance. Existing PB formulations though helpful, have some limitations in their use. This study reports on attempts to mask this unpleasant taste by complexing PB with cyclodextrins (CDs) to improve patient compliance. METHODS: α, ß and γCD were used as CDs. Phase solubility studies, circular dichroism, 1H-NMR spectroscopy, including ROESY, and molecular modelling were used to investigate and characterize the PB-CD interactions in solution. The taste-masking effect of the CDs was evaluated using in vitro taste sensor measurements. KEY FINDINGS: PB interacts with α, ß and γCD in solution to form 1:1, 1:1 and 1:2 CD: PB inclusion complexes, respectively, with stability constants in the order αCD > ßCD > γCD. Taste evaluation revealed that the CDs significantly mask the taste of PB through the formation of the inclusion complexes. Notably, αCD masked the bitter taste of PB to 30% of the initial taste at a 1:1 molar ratio. CONCLUSION: αCD significantly masks the unpleasant taste of PB in solution and can be used to formulate PB to address the limitations of existing formulations and improve patient compliance and quality of life.

The Effects of Sacran, a Sulfated Polysaccharide, on Gut Microbiota Using Chronic Kidney Disease Model Rats.

The aim of this study was to investigate the beneficial effects of sacran, a sulfated polysaccharide, on renal damage and intestinal microflora, in 5/6 nephrectomy rats as a model for chronic kidney disease (CKD). 5/6 Nephrectomy rats were divided into sacran treated and non-treated groups and examined for lethality after 4 weeks. The 5/6 nephrectomy rats were also divided into three groups: sacran treated, non-treated and AST-120 treated groups, and treated orally in a concentration-dependent manner for 4 weeks. Renal function was estimated by biochemical and histopathological analyses. Metagenomic analysis of feces from each group after 4 weeks was also performed and changes in intestinal microflora were compared. The administration of sacran to CKD rats at ≥19 mg/d increased their survival. In addition, the sacran-treated group improved CKD-related parameters in a concentration-dependent manner, and the inhibitory effect of 40 mg/d of sacran was comparable to that of AST-120. The changes in the intestinal microflora of the sacran treated group were positively correlated with an increase in the number of Lactobacillus species, which are known to be rich in beneficial bacteria, and the increment of this beneficial bacteria was negatively correlated with the concentration of indoxyl sulfate, a uremic toxin, in plasma. These results strongly suggest that the oral administration of sacran could contribute to the stabilization of intestinal microflora in CKD rats and to the reduction of oxidative stress as well as the inhibition of progression of CKD.

Supramolecular Assembly of Hybrid Pt(II) Porphyrin/Tomatine Analogues with Different Nanostructures and Cytotoxic Activities.

A simple strategy for synthesizing supramolecular hybrids was developed for the preparation of bioavailable nanohybrid photosensitizers by assembling visible-light-sensitive Pt(II) meso-tetrakis(4-carboxyphenyl)porphyrinporphyrin (PtTCPP)/tomatine analogues. The hybrids were self-assembled into nanofibrous or nanosheet structures approximately 3-5 nm thick and several micrometers wide. α-Tomatine generated a unique fibrous vesicle nanostructure based on intermolecular interactions, while dehydrotomatine generated nanosheet structures. Nanoassembly of these fibrous vesicles and sheets directly affected the properties of the light-responsive photosensitizer for tumor photodynamic therapy (PDT), depending on the nanostructure of the hybrid PtTCPP/tomatine analogues. The cytotoxicity of PtTCPP to cancer cells under photoirradiation was significantly enhanced by a tomatine assembly with a fibrous vesicle nanostructure, attributable to increased incorporation of the drug into cells.

Sacran, a sulfated polysaccharide, suppresses the absorption of lipids and modulates the intestinal flora in non-alcoholic steatohepatitis model rats.

AIMS: The objective of this study was to investigate the effects of administering sacran, a sulfated polysaccharide, on liver biology, gut microbiota, oxidative stress, and inflammation on stroke-prone spontaneously hypertensive (SHRSP5/Dmcr) rats that develop fibrotic steatohepatitis with histological similarities to that of non-alcoholic steatohepatitis (NASH). MAIN METHODS: Four groups of 8-week-old SHRSP5/Dmcr rats were fed a high fat-cholesterol (HFC) diet for 4 and 8 weeks and administered either sacran (80 mg/kg/day) or a non-treatment, respectively. Liver function was evaluated by biochemical and histopathological analyses. Hepatic inflammatory markers were measured using mRNA expression. Fecal microbial profiles were determined via 16S rRNA sequencing. A triglyceride (TG) absorption test was administered to the 8-week-old Sprague-Dawley (SD) rats. KEY FINDING: Sacran administration was observed to decrease the extent of oxidative stress and hepatic biochemical parameters in serum and hepatic injury with the levels of transforming growth factor-beta (TGF-ß1) and tumor necrosis factor-alpha (TNF-α), being increased compared to those of the non-treatment group. At the genus level, sacran administration caused a significant decrease in the harmful Prevotella genus, and a significant increase in the useful Blautia genus was observed. Sacran administration also decreased the serum TG increase that was induced by administering corn oil to the SD rats. SIGNIFICANCE: We conclude that sacran administration has the potential to reduce the absorption of lipids into blood and to improve several gut microbiotas, in the gastrointestinal tract, thereby inhibiting the subsequent development of oxidative stress and hepatic markers in the systematic circulation on NASH.

Polypseudorotaxane-based supramolecular hydrogels consisting of cyclodextrins and Pluronics as stabilizing agents for antibody drugs.

Recently, antibody drugs have been used worldwide, and based on worldwide sales, 7 of the top 10 pharmaceutical products in 2019 were antibody-based drugs. However, antibody drugs often form aggregates upon thermal and shaking stresses with few efficient stabilizing agents against both stresses. Herein, we developed polypseudorotaxane (PpRX) hydrogels consisting of cyclodextrins (CyDs) and polyethylene glycol (PEG)-polypropylene glycol (PPG)-PEG block copolymers (Pluronics F108, F87, F68, and L44), and evaluated their utility as antibody stabilizing agents. α- and γ-CyDs formed PpRX hydrogels with Pluronics, where CyD/F108 gels showed remarkable stabilizing effects for human immunoglobulin G (IgG) against both thermal and shaking stresses beyond CyD/PEG gels or generic gels. The effects were probably due to the interaction between IgG and the free PPG block of Pluronic F108, resulting in the strong IgG retention in the gels. These findings suggest the great potential of CyD/Pluronic gels as pharmaceutical materials for antibody formulations.

The preparation and validation of chitosan tablets that rapidly disperse and disintegrate as an oral adsorbent in the treatment of lifestyle-related diseases.

A carrier and an oral absorbent for the treatment of chronic diseases in the form of a tablet was prepared from granulated chitosan (G-CS) particles. The resulting tablet was highly dispersible and disintegrated rapidly (< 30 s) in aqueous media. The non-granulated chitosan (N-CS) powder partially crystallized (2θ = 12-15° and 20°) during wet granulation to give G-CS crystalline particles. The rate of penetration of water into G-CS aggregates was markedly faster than that for N-CS aggregates, as evidenced by the ease of disintegration of the tablets. The rapid disintegration and dispersion of the tablets in vivo was confirmed by MRI measurements after the oral administration of the both tablets to rats. Some ureic toxins were adsorbed more strongly to G-CS tablets than on N-CS tablets. The results suggest that G-CS tablets have great potential for use as a fast disintegrating carrier and as an oral adsorbent in lifestyle-related diseases.

Effects of surface-deacetylated chitin nanofibers on non-alcoholic steatohepatitis model rats and their gut microbiota.

Nonalcoholic steatohepatitis (NASH), a more advanced form of nonalcoholic fatty liver disease (NAFLD), is associated with increased cardiovascular and liver-related mortality. Stroke-prone spontaneously hypertensive rats (SHRSP5/Dmcr) that are fed a high-fat and high-cholesterol diet develop hepatic lesions that are similar to those observed in human NASH pathology. We investigated the hepatic protective and antioxidant effects of surface-deacetylated chitin nanofibers (SDACNFs) that were administered to SHRSP5/Dmcr rats for 8 weeks. The administration of SDACNFs (80 mg/kg/day) resulted in a significant decrease in hepatic injury, oxidative stress, compared with the non-treatment. The SDACNFs also caused a reduction in the population of harmful members of the Morganella and Prevotella genus, and increased the abundance of the Blautia genus, a useful bacterium in gut microbiota. We therefore conclude that SDACNF exerts anti-hepatic and antioxidative effects not only by adsorbing lipid substances but also by reforming the community of intestinal microflora in the intestinal tract.

Morphometric Analysis of Paramylon Particles Produced by Euglena gracilis EOD-1 Using FIB/SEM Tomography.

Euglena gracilis EOD-1, a microalgal strain, produces large quantities of paramylon, a class of polymers known as ß-1,3-glucans and has been reported to function as a dietary fiber and to improve the metabolic syndrome including obesity. However, despite its importance, the morphometric analysis of paramylon has not been conducted so far. In this study, we attempted to observe the detailed three-dimensional structure of paramylon by focused ion beam/scanning electron microscopy (FIB/SEM). Paramylon samples were fixed and three-dimensional image reconstruction and segmentation of the image stack were created using computer software (Amira v6.0.1, FEI). The results indicated that the inside of paramylon particles (diameter: 5 µm, thickness: 3 µm) was comprised of a dense structure with no evidence of the presence of large pores and gaps, although a small 100 nm crack was observed. The specific surface area of paramylon particles measured by the Brunauer-Emmet-Teller (BET) method, was not as large as activated charcoal, but similar to those of plant starches, indicating that the cholesterol-lowering effect of paramylon cannot be simply attributed to its adsorption ability. The FIB/SEM method was found to be useful for elucidating the internal structure of small solid particles.

A thermoresponsive hydrophobically modified hydroxypropylmethylcellulose/cyclodextrin injectable hydrogel for the sustained release of drugs.

The objective of this study was to develop a thermoresponsive injectable hydrogel for the sustained release of drugs by taking advantage of host-guest interactions between a hydrophobically modified hydroxypropylmethyl cellulose (HM-HPMC) and cyclodextrin (CD). A thermoresponsive injectable hydrogel was prepared by simply adding CDs to HM-HPMC hydrogel. The HM-HPMC hydrogel was converted into a sol with a low viscosity through host-guest interactions with CDs. The HM-HPMC/ß-CD hydrogel became a gel near body temperature where the host dissociated from the hydrophobic moieties of the polymer in response to the temperature. The yield stress of the HM-HPMC became progressively lower on the addition of ß-CD which was desirable in the case of developing an injectable formulation. When the HM-HPMC/ß-CD hydrogel containing indocyanine green (ICG) was subcutaneously administered to mice, the fluorescence of the ICG remained relatively constant for 24 h after the administration, which was substantially longer than that for ICG alone or an HPMC formulation. The plasma insulin level was maintained for a longer period of time when the HM-HPMC/ß-CD containing insulin was administered and the MRT value was increased by 1.6 times compared to a solution of insulin alone. In addition, the HM-HPMC/ß-CD hydrogel formulation showed a prolonged hypoglycemic effect in response to the insulin which was slowly released from the hydrogel. A thermoresponsive injectable hydrogel was successfully constructed from the highly viscous HM-HPMC and ß-CD, and the resulting formulation functioned as a sustained release carrier for drugs.

Modification of Drug Crystallization by Cyclodextrins in Pre-formulation Study.

Controlling drug crystallization is one of the important issues in pre-formulation study. In recent years, advanced approaches including the use of tailor-made additives have gathered considerable attention to control crystallization behavior of drugs. This review focuses on the use of hydrophilic cyclodextrins (CDs) as additives for controlling drug crystallization. CDs affect the crystallization of drugs in solution and in solid state based on a host-guest interaction. For example, 2,6-di-O-methyl-ß-CD and 2-hydroxybutyl-ß-CD suppressed solution-mediated transition of drugs during crystallization by the host-guest interaction; as a result, metastable forms selectively precipitated in solution. The use of CDs in crystal engineering provided an opportunity for the detection of a new polymorph by changing the crystallization pathway. It was also possible to modify crystal morphology (i.e., crystal habit) by selective suppression of crystal growth on a certain direction based on the host-gust interaction. For solid formulation, stable amorphous drug/CDs complex under humid conditions was prepared using two different CDs. An overview of some recent progress in the use of CDs in crystal engineering and in amorphous formulation is described in this review.

The Use of Enteric Capsules for Releasing a Fragrance over an Extended Period of Time.

A system for releasing a fragrance, citral (CR) over an extended period of time using three types of enteric capsules is reported. The L- and M-type capsules released CR into media with a pH above 6, while the H-type capsule released CR at a pH above 7. The pH of the releasing medium was controlled by sodium borate (SB), i.e., by adding SB-methylcellulose (MC) prepared in different weight ratios (SB-MC 1 : 2, 1 : 1 and 2 : 1) to tablets and by compressing them at different pressures. The tablet containing a large amount of SB and that was pressed at higher pressures permitted the pH of the releasing medium to be changed from 5 to 9, at 4-5 h after the addition of SB to the tablets, while negligible changes were observed for tablets containing low amounts of SB and which were compressed at lower pressures. Reflecting these pH changes, CR was released after different periods of time when SB-MC tablets and capsules containing CR were simultaneously added to the releasing medium. When enteric capsules containing CR and the pH adjusting tablets were simultaneously added to a benzyl acetate (BA) solution, BA was released at a constant rate, while CR was released for different periods of time depending on the type of capsule used. The results suggest that fragrances could be released over different time frames by using enteric capsules and pH adjusting agents, for example, the release of fragrances with sedative effects at night time and with stimulating effects in the morning.

In Vitro and In Vivo Evaluation of 6-O-α-Maltosyl-ß-Cyclodextrin as a Potential Therapeutic Agent Against Niemann-Pick Disease Type C.

Niemann-Pick disease Type C (NPC) is a rare lysosomal storage disease characterized by the dysfunction of intracellular cholesterol trafficking with progressive neurodegeneration and hepatomegaly. We evaluated the potential of 6-O-α-maltosyl-ß-cyclodextrin (G2-ß-CD) as a drug candidate against NPC. The physicochemical properties of G2-ß-CD as an injectable agent were assessed, and molecular interactions between G2-ß-CD and free cholesterol were studied by solubility analysis and two-dimensional proton nuclear magnetic resonance spectroscopy. The efficacy of G2-ß-CD against NPC was evaluated using Npc1 deficient Chinese hamster ovary (CHO) cells and Npc1 deficient mice. G2-ß-CD in aqueous solution showed relatively low viscosity and surface activity; characteristics suitable for developing injectable formulations. G2-ß-CD formed higher-order inclusion complexes with free cholesterol. G2-ß-CD attenuated dysfunction of intercellular cholesterol trafficking and lysosome volume in Npc1 deficient CHO cells in a concentration dependent manner. Weekly subcutaneous injections of G2-ß-CD (2.9 mmol/kg) ameliorated abnormal cholesterol metabolism, hepatocytomegaly, and elevated serum transaminases in Npc1 deficient mice. In addition, a single cerebroventricular injection of G2-ß-CD (21.4 µmol/kg) prevented Purkinje cell loss in the cerebellum, body weight loss, and motor dysfunction in Npc1 deficient mice. In summary, G2-ß-CD possesses characteristics favorable for injectable formulations and has therapeutic potential against in vitro and in vivo NPC models.

Design and Evaluation of An Extended-Release Olmesartan Tablet Using Chitosan/Cyclodextrin Composites.

Sustained-release olmesartan tablets (OLM) were prepared by the simple, direct compression of composites of anionic sulfobutyl ether-ß-cyclodextrin (SBE-ß-CD) and cationic spray-dried chitosan (SD-CS), and were evaluated for use as a sustained release preparation for the treatment of hypertension. An investigation of the interaction between OLM and SBE-ß-CD by the solubility method indicated that the phase diagram of the OLM/SBE-ß-CD system was the AL type, indicating the formation of a 1:1 inclusion complex. The release of OLM from tablets composed of the SD-CS/SBE-ß-CD composite was slow in media at both pH 1.2 and at 6.8. The in vitro slow release characteristics of the SD-CS/SBE-ß-CD composite were reflected in the in vivo absorption of the drug after normal rats were given an oral administration of the preparation. Furthermore, the SD-CS/SBE-ß-CD composite continuously increased the antihypertensive effect of OLM in hypertensive rats, compared with that of the drug itself. These results suggest that a simple mixing of SD-CS and SBE-ß-CD can be potentially useful for the controlled release of a drug for the continuous treatments of hypertension.

Preparation and evaluation of freeze dried surface-deacetylated chitin nanofiber/sacran pellets for use as an extended-release excipient.

Pelleted preparations were formulated from sacran (Sac), an anionic, sulfated, carboxyl-containing polysaccharide, which is extracted from the Japanese indigenous cyanobacterium Aphanothece sacrum, and surface-deacetylated chitin nanofibers (SDACNF). The use of this material as an extended-release excipient for tetrahydrocurcumin (THC), a model drug that is used to treat wounds via its radical scavenging ability was examined. The THC used in the study was complexed with 2-hydroxypropyl-ß-cyclodextrin (HP-ß-CD), which increases its water solubility. The radical scavenging activity of the THC/HP-ß-CD complex (molar ratio of 1:1) was significantly higher than the values for SDACNF or Sac alone. The rate of release of THC from the Sac/SDACNF pellets containing the THC/HP-ß-CD complex decreased with increasing Sac content in the pellet, suggesting that Sac/SDACNF (1:1) and Sac alone pellets function as extended-release excipients for THC. The findings reported here indicate that this can be attributed to the ability of the Sac component to retain fluids, thus extending the effects of the drug. In view of the above experimental outcomes, i.e. wound healing efficacy, fluid absorption, retention and the extended drug release of the system indicates that this preparation, in the appropriate ratios, has the potential for use as a controlled-release drug in wound healing.

Antioxidant activities of chitosans and its derivatives in in vitro and in vivo studies.

This review focuses on the in vitro and in vivo antioxidant activities of various chitosan preparations, including those with different molecular weights and degrees of acetylation and the nanofibers produced from them. In in vitro studies, low molecular weight (LMW) chitosan with high degrees of deacetylation has more potent antioxidant properties than those of high molecular weight (HMW) chitosan. On the other hand, HMW chitosan has higher adsorption properties than those of LMW chitosan. On the basis of the in vitro results obtained, the ingestion of chitosan and nanofiber derived from it, with moderate MW and degrees of acetylation results in a significant reduction in oxidative stress in several chronic oxidative stress related diseases such as the metabolic syndrome and renal failure. In the future, chitosan and related nanofibers with presumed antioxidant properties may be used as a new source of antioxidant, as a possible food supplement, as an ingredient or in the pharmaceutical industry.

Synthesis, Aggregation Behavior, and Photodynamic Properties of a Water-Soluble Fulleropyrrolidine Bearing an N-PEG Pyridinium Unit.

Herein, we describe the synthesis of a water-soluble photodynamically active fullerene bearing a polyethylene glycol chain and a hydrophilic cationic group, revealing that the solubility of the above derivative in aqueous medium depends on ultrasonication time, with the particle size of aggregates being correlated with concentration.

Glucose Responsive Rheological Change and Drug Release from a Novel Worm-like Micelle Gel Formed in Cetyltrimethylammonium Bromide/Phenylboronic Acid/Water System.

A novel glucose (Glc)-responsive gel formed by worm-like micelles (WLMs) has the potential to provide a self-regulating insulin delivery system. We have prepared a WLM gel system using 75 mM cetyltrimethylammonium bromide, 75 mM phenylboronic acid, and water. At pH 9.4, this gel-like system was highly viscous and supported its own weight, and dynamic viscoelasticity measurement indicated that it contained long and entangled WLMs. The visual observation of gels prepared to include >6 mM Glc revealed that these adopted a sol-like appearance, whereas those prepared to include a control compound (2-10 mM diethylene glycol) retained their gel-like appearance. The storage modulus ( G') of this system decreased as the Glc concentration increased (2-10 mM), indicating a gradual shortening of the WLMs. In vitro release was evaluated using a test compound (fluorescein isothiocyanate dextran) in a microsized flow system. By 120 min, the release of this compound from the WLM gel was around 27-fold greater in the presence of 100 mM Glc than without Glc or with 100 mM diethylene glycol. This demonstrated the successful preparation of a WLM gel that showed an altered drug release rate, depending on Glc concentration.

Surface-deacetylated chitin nanofibers reinforced with a sulfobutyl ether ß-cyclodextrin gel loaded with prednisolone as potential therapy for inflammatory bowel disease.

Surface-deacetylated chitin nanofibers (SDACNFs) reinforced with a sulfobutyl ether ß-cyclodextrin (SBE-ß-CD) (NFs-CDs) gel were developed to obtain a controlled release carrier of prednisolone (PD) for the treatment of colitis. PD was released slowly from the gel at both pH 1.2 and 6.8. The in vitro slow release of PD from the NFs-CDs gel was reflected in the in vivo absorption of the drug after oral administration to rats. These results suggest that a simple gel composed of a mixture of SDACNFs and SBE-ß-CD has the potential for use in the controlled release of PD. We also evaluated the therapeutic effects of the NFs-CDs gel containing PD on dextran sulfate sodium (DSS)-induced colitis model mice. The administration of the NFs-CDs gel at intervals of 3days from the beginning of the DSS treatment resulted in a significant improvement, not only in colitis symptoms but also histopathological changes in colon tissue. In addition, the therapeutic effects of the NFs-CDs gel on colitis can be attributed to decreased levels of neutrophil infiltration and the development of oxidative stress. These efficacy profiles of the NFs-CDs gel containing PD suggest that it has the potential for use in the treatment of, not only colitis, but also a variety of other disorders associated with inflammation and oxidative injuries.