Physical characterisation and component release of poly(vinyl alcohol)–tetrahydroxyborate hydrogels and their applicability as potential topical drug delivery systems

Physicochemical and in vitro biological evaluation of an injectable self-healing quaternized chitosan/oxidized pectin hydrogel for potential use as a wound dressing material

Injectable self-healing hydrogels are attractive materials for use as wound dressings. To prepare such hydrogels, the current study used quaternized chitosan (QCS) to improve the solubility and antibacterial activity and oxidized pectin (OPEC) to introduce aldehyde groups for Schiff's base reaction with the amine groups from QCS. Self-healing hydrogels were made by co-injection of polymer solutions at specific polymer concentrations and reagent ratios that optimized both Schiff's base reactions and ionic interactions. The optimal hydrogel displayed self-healing 30 min after cutting and continuous self-healing during continuous step strain analysis, rapid gelation (< 1 min), a storage modulus of 394 Pa, and hardness of 700 mN, and compressibility of 162 mN s. The adhesiveness of this hydrogel (133 Pa) was within a suitable range for application as a wound dressing. The extraction media from the hydrogel displayed no cytotoxicity to NCTC clone 929 cells and higher cell migration than the control. While the extraction media from the hydrogel was found not to have antibacterial properties, QCS was verified as having MIC50 of 0.04 mg/mL against both E. coli and S. aureus. Therefore, this injectable self-healing QCS/OPEC hydrogel has the potential use as a biocompatible hydrogel material for wound management.

Wound-aided semi-solid poly(vinyl alcohol) hydrogels incorporating essential oil-loaded chitosan nanoparticles

The potential of chitosan nanoparticles (CSNPs) loaded with essential oil (EO) incorporated into semi-solid PVA hydrogels for use in wound management was studied. Two types of essential oil were compared including clove essential oil (CEO) and turmeric essential oil (TEO). The EO-loaded CSNPs were prepared by a two-step method; oil-in-water (o/w) emulsification followed by ionic gelation using different ratios of chitosan:EO (i.e., 1:0.25, 1:0.50, 1:0.75, and 1:1.00 w/w). The increasing amount of EO caused more aggregate structure as observed from SEM images. The TEO-loaded CSNPs showed a higher extent of aggregation than the CEO-loaded CSNPs. The adhesiveness of the semi-solid PVA hydrogels containing TEO-loaded CSNPs was the highest. The use of EO-loaded CSNPs in the semi-solid PVA hydrogel helped to sustain and prolong the release rate of EO from the hydrogels as compared to just the EO alone. The studied semi-solid PVA hydrogels were non-toxic to both NCTC clone 929 and NHDF cells. Overall results suggested that these semi-solid hydrogels are good candidates for use in wound management.

A review on preparations, properties, and applications of cis-ortho-hydroxyl polysaccharides hydrogels crosslinked with borax

Polysaccharides-based hydrogel has many advantages such as biocompatibility, self-repair property, and biodegradability. It has been widely applied in various fields and has attracted great attention of researchers. The natural polysaccharides involved in this review include fenugreek gum, guar gum, locust bean gum, gellan gum, sodium alginate, agarose, and konjac glucomannan etc. Borax is a highly effective crosslinking agent for cis-ortho-hydroxyl polysaccharides. This paper focused on the synthesis mechanism, functional additives, characteristics, and applications of borax crosslinked cis-ortho-hydroxyl polysaccharides hydrogels (BHs). Moreover, the factors affecting BHs performance such as temperature, pH, and media were analyzed. Its mechanical and self-repair properties are enhanced by the dynamic and reversible borate/di-diol, which play a significant role in sensors, biomedicine, and tissue engineering. This review summarizes the research progress of BHs for the first time. Additionally, hoping to contribute to the development of this field, the review analyzes the correlation of performance through the SPSS 26 software.

PLGA based film forming systems for superficial fungal infections treatment

As proven in clinical trials, superficial fungal infections can be effectively treated by single topical application of terbinafine hydrochloride (Ter-HCl) in a film forming system (FFS). Poly(lactic-co-glycolic acid) (PLGA) derivatives, originally synthesized with intention to get carriers with optimized properties for drug delivery, and multifunctional plasticizers - ethyl pyruvate, methyl salicylate, or triacetin - were used for formulation of Ter-HCl loaded FFSs. After spraying, a biodegradable, transparent, adhesive, and occlusive thin layer is formed on the skin, representing drug depot. In situ formed films were characterized by thermal, structural, viscoelastic, and antifungal properties as well as drug release and skin penetration. DSC and SEM showed fully amorphous films with Ter-HCl dissolved in PLGA in high concentration (up to 15%). FFSs are viscoelastic fluids with viscosity which can be easily adjusted by the type of plasticizer used and its concentration. The formulations showed excellent bioadhesion properties, thus ensuring persistence on the skin. In situ film based on branched PLGA/A plasticized with 10% of ethyl pyruvate allowed prolonged release of Ter-HCl by linear kinetics for the first 6 days with a total time of almost 14 days. During ex vivo human skin penetration experiment, Ter-HCl was found to be located only in its target layer, the epidermis. According to our results, plasticized branched PLGA derivatives loaded by Ter-HCl are suitable for the development of FFSs for superficial fungal infections treatment.

Ecotoxicological Properties of Tulipalin A-Based Superabsorbents versus Conventional Superabsorbent Hydrogels

The Phytotoxicological Aspects of a Novel Superabsorbent/Hydrogels: poly(acrylamide-co-sodium 4-hydroxy-2-methylenebutanoate), prepared from renewable monomer Tulipalin A, on the growth and development of monocotyledonous Avena sativa and dicotyledonous Raphanus sativus, was investigated and compared with the effect of borate-crosslinked poly(vinyl alcohol), poly(acrylamide), and poly(acrylamide-co-sodium acrylate) conventional hydrogels. Tulipalin A-based superabsorbent hydrogels revealed superior properties in terms of the combination of the tested properties. The results confirmed excellent suitability of Tulipalin A-based hydrogels for application as reservoirs of water during plant stress condition. Values of fresh matter (yield) and shoot height of the examined plants growing in soil amended with these hydrogels were ca 10% higher than those of plants growing in soil without hydrogels. Reference borate-crosslinked PVA hydrogels (containing increasing amount of borax cross-linker) revealed harmful effect on plants. The negative effect was observed on most of the investigated properties, increasing with content of the hydrogel in soil and concentration of the borax in it.

Design of a Versatile pH-Responsive Hydrogel for Potential Oral Delivery of Gastric-Sensitive Bioactives

A pH-responsive hydrogel system was prepared by free radical polymerization of acrylamide and methyl acrylic acid in the presence of N-N′-methylene bisacrylamide. Sodium bicarbonate was further applied as a blowing agent, which afforded a porous hydrogel structure. The hydrogel system achieved a constant super swelling rate within simulated intestinal buffer (~4%/min) and remained relatively static within simulated gastric buffer (~0.8%/min). The hydrogel system was able to achieve matrix resilience greater than 30% under a relatively high strain of 40%. In addition, the hydrogel system demonstrated significant swelling properties in response to simulated intestinal environmental over 24 h, with contrasting characteristics in simulated gastric buffer. The hydrogel demonstrated type IV isotherm porosity characteristics, with remarkable MRI and SEM variations in gastric and intestinal simulated fluids. Drug loading was observed to be greater than 98% using theophylline as a prototype drug, evaluating its controlled release kinetics over 24 h. The hydrogel exhibited substantial pH-responsive activity, which could be used as a versatile platform for targeted release of gastric-sensitive therapeutics to the small intestine.

Design and Evaluation of Topical Diclofenac Sodium Gel Using Hot Melt Extrusion Technology as a Continuous Manufacturing Process with Kolliphor® P407

The aim of the present context was to develop and evaluate a Kolliphor® P407-based transdermal gel formulation of diclofenac sodium by hot melt extrusion (HME) technology; central composite design was used to optimize the formulation process. In this study, we have explored first time ever HME as an industrially feasible and continuous manufacturing technology for the manufacturing of gel formulation using Kolliphor® P407 and Kollisolv® PEG400 as a gel base. Diclofenac sodium was used as a model drug. The HME parameters such as feeding rate, screw speed, and barrel temperature were crucial for the semisolid product development, and were optimized after preliminary trials. For the processing of the gel formulation by HME, a modified screw design was used to obtain a uniform product. The obtained product was evaluated for physicochemical characterization such as differential scanning calorimetry (DSC), X-ray diffraction (XRD), pH measurement, rheology, surface tension, and texture profile analysis. Moreover, it was analyzed for general appearance, spreadibility, surface morphology, and drug content. The optimized gel formulation showed homogeneity and transparent film when applied on a glass slide under microscope, pH was 7.02 and uniform drug content of 100.04 ± 2.74 (SD = 3). The DSC and XRD analysis of the HME gel formulation showed complete melting of crystalline API into an amorphous form. The Kolliphor® P407 and Kollisolv® PEG400 formed excellent gel formulation using HME with consistent viscoelastic properties of the product. An improved drug release was found for the HME gel, which showed a 100% drug release than that of a marketed product which showed only 88% of drug release at the end of 12 h. The Flux value of the HME gel was 106 than that of a marketed formulation, which showed only about 60 value, inferring a significant difference (P < 0.05) at the end of 1 h. This study demonstrates a novel application of the hot melt extrusion process for manufacturing of topical semisolid products.

Influence of colloidal silicon dioxide on gel strength, robustness, and adhesive properties of diclofenac gel formulation for topical application

The objective of this study is to identify the extent of stiffness, adhesiveness, and thixotropic character of a three-dimensional gel network of a 1% diclofenac sodium topical gel formulation in the presence and absence of colloidal silicon dioxide (CSD) and assess its ease of application and adhesiveness using both objective and subjective analysis. The 1% diclofenac gel was mixed with different amounts of CSD (e.g., 0.5, 1, 2, 3, and 5% w/w) and allowed to equilibrate prior to testing. The texture analyzer in combination with a cone-cap assembly was used to objectively investigate the changes in spreadability and adhesiveness of the gel system before and after addition of CSD. Results indicate that an increase in pliability and adhesiveness at levels ≥2 to ≤5% w/w of CSD dispersed in the gel ensues. For subjective analysis, gels with (2% w/w) CSD and in the absence of CSD were uniformly applied to a 20-cm(2) (5 cm × 4 cm) surface area on the forearms of healthy volunteers and vehicle preferences by the volunteers regarding ease of application, durability on the skin, compliance, and feelings concerning its textural properties were assessed. It appears that changes in the gel formulation with the addition of CSD enhance gel viscosity and bonding to the skin. Results further show that changes in physical and rheological characteristics of gel containing 2% w/w CSD did not significantly change subject preferences for the gel preparations. These findings may help formulators to have additional options to develop more robust and cost-effective formulations.

Nanotechnology-Based Drug Delivery Systems for Melanoma Antitumoral Therapy: A Review

Melanoma (MEL) is a less common type of skin cancer, but it is more aggressive with a high mortality rate. The World Cancer Research Fund International (GLOBOCAN 2012) estimates that there were 230,000 new cases of MEL in the world in 2012. Conventional MEL treatment includes surgery and chemotherapy, but many of the chemotherapeutic agents used present undesirable properties. Drug delivery systems are an alternative strategy by which to carry antineoplastic agents. Encapsulated drugs are advantageous due to such properties as high stability, better bioavailability, controlled drug release, a long blood circulation time, selective organ or tissue distribution, a lower total required dose, and minimal toxic side effects. This review of scientific research supports applying a nanotechnology-based drug delivery system for MEL therapy.

Development and characterization of a hydrogel containing silver sulfadiazine for antimicrobial topical applications

Development and optimization of a hydrogel with impregnated silver sulfadiazine was pursued, for antimicrobial topical applications. The selected hydrogel exhibited a homogeneous appearance, with whitish colloration and devoid of any fractures or cracks. The content in impregnated silver sulfadiazine was within established limits (1%, w/w) with a standard deviation of up to 1.28%. The hydrogel presented a good characteristic in relation to release of the active antimicrobial principle, verified through swelling tests and antimicrobial activity. The swelling tests indicated a higher increase in weight during the first 6 h of contact with a moist environment, with a maximum value of 266.00 ± 0.81, and with maintenance of the original shape of the hydrogel. The impregnated silver sulfadiazine presented antimicrobial activity, as expected, indicating a prolonged release of the drug. The infrared spectra of the hydrogel with impregnated silver sulfadiazine indicated that the drug did not engage in any bonds with the polymeric matrix, which otherwise could have reduced its antimicrobial activity. The mechanical resistance tests produced good results, indicating that the hydrogels may be utilized in different locations of the human body with skin lesions.

Rheological characterization of cataplasm bases composed of cross-linked partially neutralized polyacrylate hydrogel

Viscoelasticity is a useful parameter for characterizing the intrinsic properties of the cross-linked polyacrylate hydrogel used in cataplasm bases. The aim of this study was to investigate the effects of various formulation parameters on the rheological characteristics of polyacrylate hydrogel. The hydrogel layers were formed using a partially neutralized polyacrylate (Viscomate(™)), which contained acrylic acid and sodium acrylate in different copolymerization ratios, as the cross-linked gel framework. Dihydroxyaluminum aminoacetate (DAAA), which produces aluminum ions, was used as the cross-linking agent. Rheological analyses were performed using a "stress amplitude sweep" and a "frequency sweep". The results showed that greater amounts of acrylic acid in the structure of Viscomate as well as higher concentrations of DAAA and Viscomate led to an increase in the elastic modulus (G'). However, greater amounts of acrylic acid in the structure of Viscomate and higher concentrations of DAAA had an opposite on the viscous modulus (G″); this might be owing to higher steric hindrance. The results of this study can serve as guidelines for the optimization of formulations for cataplasms.

A non-inferiority randomized controlled trial comparing the clinical effectiveness of anesthesia obtained by application of a novel topical anesthetic putty with the infiltration of lidocaine for the treatment of lacerations in the emergency department

STUDY OBJECTIVE

We test the hypothesis that anesthesia, measured as pain scores, induced by a novel topical anesthetic putty is non-inferior (margin=1.3) to that provided by conventional lidocaine infiltration for the repair of lacerations.

METHODS

A randomized controlled trial was conducted in the emergency department (ED) of a local hospital. Participants were randomly allocated to receive either infiltration anesthesia or topical anesthetic putty as per the trial protocol. Pain scores were recorded 15 minutes after infiltration and 30 minutes after topical anesthetic putty application. Median pain scores were compared between groups. Wound evaluation scores were conducted after 7 to 10 days and adverse events were monitored for both groups of participants throughout the study.

RESULTS

One hundred and ten participants were enrolled in the study, with 56 receiving infiltration and 54 receiving topical anesthetic putty. The median difference between the pain scores of the 2 groups was 0 (95% confidence interval -1 to 0). There were no substantial differences between the 2 groups in terms of either the wound evaluation scores or the incidence of adverse events.

CONCLUSION

The novel topical anesthetic putty was not inferior to infiltration with lidocaine with respect to the pain experienced during suturing, and this putty is a feasible alternative to infiltration anesthesia of lacerations in the ED.

Physicomechanical characterization and optimization of EDTA-mPEG and Avicel®-EDTA-mPEG in situ melt dispersion mini-pellets

The purpose of this study was to develop a physicomechanically customizable oral metal chelatory in situ hot melt dispersion mini-pellet entity which could be utilized within a binary drug delivery system. Avicel(®) RC/CL type R-591 was included within the in situ hot melt dispersion mini-pellet formulations to determine the physicomechanical effect this compound would have on the mini-pellet formulations. The physicomechanical properties of the hot melt in situ mini-pellet formulations were mathematically fitting to regression curves. Physicomechanical adjustment of the in situ hot melt dispersion mini-pellet formulations could be mathematically predicted with the derived regression curve equations. The addition of Avicel(®) RC/CL type R-591 increased the physicomechanical properties such as matrix hardness and increased total disintegration of the in situ hot melt dispersion mini-pellet formulations. The utilization of a physicomechanically customizable oral metal chelatory in situ hot melt dispersion mini-pellet entity within a binary drug delivery system would to achieve a synergistically enhance the activity of a drug-carrying entity or a permeation enhancing entity within a single drug delivery unit. The experimental results indicated that weights of the pellets that achieved optimal hardness ranged between 35 and 45 mg. The melt-dispersion formulations disintegrated within shorter time periods and maintained higher ethylenediaminetetraacetic acid (EDTA) concentrations whereas melt-dispersion formulations which included Avicel(®) had superior physicomechanical properties. Disintegration times ranged between 1,000 s for melt-dispersions containing EDTA and methyloxy polyethylene glycol 2000 (mPEG) only, to >6,000 s for melt-dispersions comprising EDTA, mPEG, and Avicel(®).

Drug diffusion from disperse systems with a hydrophobically modified polysaccharide: Enhancer vs Franz cells

This study assesses the capacity of a new hydrophobically modified polysaccharide -hydroxypropyl cellulose-methyl methacrylate - to control drug release in semisolid formulations. The dispersed systems contain the new polymer, Igepal CO520 as surfactant and theophylline as model drug at three concentrations (0.5, 1 and 1.5%, w/w). Drug release study shows that the systems containing 0.5% (w/w) of drug have faster release and higher diffusion coefficient than the other two concentrations. These results can be explained by two different structures ("relaxed" and "structured") found from a rheological point of view. Also, this paper compares two different devices for testing drug release and diffusion. It has been obtained more reliable and reproducible results with Enhancer Cell respect to Franz diffusion cell. In both cases, Fickian diffusion was the mechanism predominant for all systems. Finally, the utility of this polymer has been demonstrated to make three-dimensional gel structure and control theophylline release from systems in topical application.