Designed sponges based on chitosan and cyclodextrin polymer for a local release of ciprofloxacin in diabetic foot infections

Diabetic foot infections are the most common complications requiring hospitalisation of patients with diabetes. They often result in amputation to extremities and are associated with high morbi-mortality rates, especially when bone is infected. Treatment of these complications is based on surgical procedures, nursing care and systemic antibiotic therapy for several weeks, with a significant risk of relapse. Due to low blood flow and damage caused by diabetic foot infection, blood supply is decreased, causing low antibiotic diffusion in the infected site and an increase of possible bacterial resistance, making this type of infection particularly difficult to treat. In this context, the aim of this work was to develop a medical device for local antibiotic release. The device is a lyophilized physical hydrogel, i.e a sponge based on two oppositely charged polyelectrolytes (chitosan and poly(cyclodextrin citrate)). Cyclodextrins, via inclusion complexes, increase drug bioavailability and allow an extended release. Using local release administration increases concentrations in the wound without risk of toxicity to the body and prevents the emergence of resistant bacteria. The hydrogel was characterised by rheology. After freeze-drying, a curing process was implemented. The swelling rate and cell viability were evaluated, and finally, the sponge was impregnated with a ciprofloxacin solution to evaluate its drug release profile and its antibacterial activity.

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-β-cyclodextrin (SBE-β-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-β-CD by the solubility method indicated that the phase diagram of the OLM/SBE-β-CD system was the A_L type, indicating the formation of a 1:1 inclusion complex. The release of OLM from tablets composed of the SD-CS/SBE-β-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-β-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-β-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-β-CD can be potentially useful for the controlled release of a drug for the continuous treatments of hypertension.

Influence of the Soluble⁻Insoluble Ratios of Cyclodextrins Polymers on the Viscoelastic Properties of Injectable Chitosan⁻Based Hydrogels for Biomedical Application

Injectable pre-formed physical hydrogels provide many advantages for biomedical applications. Polyelectrolyte complexes (PEC) formed between cationic chitosan (CHT) and anionic polymers of cyclodextrin (PCD) render a hydrogel of great interest. Given the difference between water-soluble (PCDs) and water-insoluble PCD (PCDi) in the extension of polymerization, the present study aims to explore their impact on the formation and properties of CHT/PCD hydrogel obtained from the variable ratios of PCDi and PCDs in the formulation. Hydrogels CHT/PCDi/PCDs at weight ratios of 3:0:3, 3:1.5:1.5, and 3:3:0 were elaborated in a double–syringe system. The chemical composition, microstructure, viscoelastic properties, injectability, and structural integrity of the hydrogels were investigated. The cytotoxicity of the hydrogel was also evaluated by indirect contact with pre-osteoblast cells. Despite having similar shear–thinning and self-healing behaviors, the three hydrogels showed a marked difference in their rheological characteristics, injectability, structural stability, etc., depending on their PCDi and PCDs contents. Among the three, all the best above-mentioned properties, in addition to a high cytocompatibility, were found in the hydrogel 3:1.5:1.5. For the first time, we gained a deeper understanding of the role of the PCDi/PCDs in the injectable pre-formed hydrogels (CHT/PCDi/PCDs), which could be further fine-tuned to enhance their performance in biomedical applications.

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-β-cyclodextrin (HP-β-CD), which increases its water solubility. The radical scavenging activity of the THC/HP-β-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-β-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.

Biomaterials based on freeze dried surface-deacetylated chitin nanofibers reinforced with sulfobutyl ether β-cyclodextrin gel in wound dressing applications

A freeze-dried gel composed of surface-deacetylated chitin nanofibers (SDACNFs), reinforced with an anionic cyclodextrin, sulfobutyl ether β-cyclodextrin (SBE-β-CD) was evaluated for treating wounds in a rat model, and the results were compared with a SDACNFs gel without SBE-β-CD. The incorporation of prednisolone (PD), a poorly water-soluble drug, in both types of gels and its release from the gels were also compared. In both cases, wound areas were decreased and their effect was higher than that of commercially available wound dressings. The rate of release of PD from the freeze-dried SDACNFs/SBE-β-CD was much faster than that form SDACNFs alone without SBE-β-CD, due to fact that the PD is more soluble in the amorphous SBE-β-CD complex compared to the other preparations. The findings indicate that the freeze-dried SDACNFs/SBE-β-CD gel would be beneficial as a new biomaterial for the treatment of wounds and for preparing homogeneous high-content gels that contain poorly water-soluble drugs.

Surface-Deacetylated Chitin Nano-Fiber/Hyaluronic Acid Composites as Potential Antioxidative Compounds for Use in Extended-Release Matrix Tablets

In this study, we examined a possible use of a surface-deacetylated chitin nano-fiber (SDCH-NF) and hyaluronic acid (HA) interpolymer complex (IPC) tablet as a potential antioxidative compound in extended-release matrix tablets. The antioxidant properties of untreated chitin (UCH), SDCH-NF, and HA were examined using N-centered radicals derived from 1,1'-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). SDCH-NF and HA had acceptable scavenging abilities and were relatively efficient radical scavengers, but UCH was much less effective. The results suggest that SDCH-NF and HA could serve as scavengers of compounds related to the development of oxidative stress. An SDCH-NF/HA IPC tablet was prepared and evaluated as an extended-release tablet matrix using famotidine (FMT) as a model drug. The release of FMT from the IPC tablet (DCF-NF:HA=1:1) was slower than that from a SDCH-NF only tablet. Turbidity measurements and X-ray diffraction (XRD) data also indicated that the optimum complexation ratio for IPC between SDCH-NF/HA is 1/1, resulting in a good relationship between turbidity or XRD of the complex and the release ratio of FMT. These results suggest that an SDCH-NF/HA tablet has the potential for use in an extended-release IPC tablet with a high antioxidant activity.

Slow-release of famotidine from tablets consisting of chitosan/sulfobutyl ether β-cyclodextrin composites

An intermolecular complex formed from a 1:1 weight ratio of chitosan (CS, molecular weight 30 kDa) and sulfobutyl ether β-cyclodextrin (SBE-β-CyD, degree of substitution 7) was less soluble than either of the original components. The release of famotidine from tablets composed of a simple mixture of CS and SBE-β-CyD is slower in media at pH 1.2 than at 6.8. Macroscopic observation of tablets and a kinetic analysis of release profiles suggested that, at pH 1.2, the drug was slowly released from the less-soluble CS/SBE-β-CyD complex formed on the surface of the tablet immediately after exposure to water, accompanied by the dissolution of the interpolymer complex and, ultimately, the erosion and disintegration of the tablet. In the case of the medium at pH 6.8, the formation of a gel by CS was the cause of the slow release, especially for CS/SBE-β-CyD tablets which were significantly gelated and both the diameter and thickness of the tablet had expanded. The in vitro slow releasing characteristic of the CS/SBE-β-CyD tablet was reflected in the in vivo absorption of the drug after oral administration to rats. These results suggest that a simple mixing of CS and SBE-β-CyD is potentially useful for the controlled release of a drug.