Moldable Tissue-Sealant Hydrogels Composed of In Situ Cross-Linkable Polyethylene Glycol via Thiol-Michael Addition and Carbomers

Moldable tissue-sealant hydrogels were developed herein by combining the yield stress fluidity of a Carbomer and in situ cross-linking of 3-arm PEG-thiol (PEG-SH) and 4-arm PEG-acrylate (PEG-AC). The Carbomer was mixed with each PEG oligomer to form two aqueous precursors: Carbomer/PEG-SH and Carbomer/PEG-AC. The two hydrogel precursors exhibited sufficient yield stress (>100 Pa) to prevent dripping from their placement on the tissue surface. Moreover, these hydrogel precursors exhibited rapid restructuring when the shear strain was repeatedly changed. These rheological properties contribute to the moldability of these hydrogel precursors. After mixing these two precursors, they were converted from yield-stress fluids to chemically cross-linked hydrogels, Carbomer/PEG hydrogel, via thiol-Michael addition. The gelation time was 5.0 and 11.2 min at 37 and 25 °C, respectively. In addition, the Carbomer/PEG hydrogels exhibited higher cellular viability than the pure Carbomer. They also showed stable adhesiveness and burst pressure resistance to various tissues, such as the skin, stomach, colon, and cecum of pigs. The hydrogels showed excellent tissue sealing in a cecum ligation and puncture model in mice and improved the survival rate due to their tissue adhesiveness and biocompatibility. The Carbomer/PEG hydrogel is a potential biocompatible tissue sealant that surgeons can mold. It was revealed that the combination of in situ cross-linkable PEG oligomers and yield stress fluid such as Carbomer is effective for developing the moldable tissue sealant without dripping of its hydrogel precursors.

Edible Gels with Cranberry Extract: Evaluation of Anthocyanin Release Kinetics

The bioactive compounds found in cranberry fruit are natural antioxidants, and their consumption reduces the risk of diabetes, cardiovascular disease, cancers, and urinary tract infections. Oral gels with cranberry fruit extract are a promising product that can ensure accurate dosage and release of the active compounds and are suitable for people with dysphagia. The aim of this study was to determine the effect of polymeric materials on the dissolution kinetics of cranberry fruit anthocyanins from gel formulations. Gel formulations were prepared using freeze-dried cranberry fruit extract with different gelling excipients: chitosan (G1-G3), sodium carboxymethylcellulose (G4-G6), and sodium carboxymethylcellulose combined with carbomers (G7-G9). The dissolution test showed that the release of anthocyanins from gel formulations G1-G6 and G9 was most intense within the first 10 min, with little change in the anthocyanin content of the acceptor medium afterwards. For the formulations based on carboxymethyl cellulose and carbomers G7 and G8, the amount of anthocyanins released into the acceptor medium gradually increased, which prolonged the release time of the active compounds. The test for the release of anthocyanins from the semi-solid systems through a hydrophilic membrane revealed that within the first hour, the total amount of anthocyanins released from the modeled gel formulations (G1-G9) was within the range of 6.02%-13.50%. The 1% chitosan (G1) gel formulation released the fastest and highest amount of anthocyanins (70% within 6 h). The other formulations showed a slower release of anthocyanins, and after 6 h, the amount of anthocyanins released from formulations G2-G9 was <57%.

Multifunctional Drugs-Loaded Carbomol Hydrogel Promotes Diabetic Wound Healing via Antimicrobial and Immunoregulation

Diabetic wound healing poses a significant clinical dilemma. Bacterial infection and immune dysregulation are the predominant reasons. However, conventional wound dressings with a single treatment approach often limit therapeutic efficacy and continue working with difficulty. These limitations cause high treatment failure for diabetic wounds. In this study, we developed a multiple drug-loaded carbomer hydrogel containing Que/Van/Rif (QVR-CBMG) for the simultaneous treatment of infection and immune dysregulation. Honeycomb-like QVR-CBMG hydrogel exhibits excellent abilities to eliminate bacterial infection and biofilms in vitro. Moreover, QVR-CBMG hydrogel possesses an immunomodulatory capacity via affecting the Sirt3/SOD2 signaling pathway to promote M2 macrophages. Furthermore, QVR-CBMG hydrogel effectively promotes wound healing in diabetic rats through several mechanisms. The multidrug-loaded wound dressing not only eliminates bacterial infection and facilitated angiogenesis but also promotes collagen deposition and remodulates the local immune microenvironment in the areas of wounds. In summary, this synthetic strategy to eliminate infection and regulate immune disorders has potential translational value for the prevention and management of diabetic wounds.

Emulsion-Based Gel Loaded with Ibuprofen and Its Derivatives

The aim of this study was to evaluate the effect of vehicle and chemical modifications of the structure of active compounds on the skin permeation and accumulation of ibuprofen (IBU). As a result, semi-solid formulations in the form of an emulsion-based gel loaded with ibuprofen and its derivatives, such as sodium ibuprofenate (IBUNa) and L-phenylalanine ethyl ester ibuprofenate ([PheOEt][IBU]), were developed. The properties of the obtained formulations were examined, including density, refractive index, viscosity, and particle size distribution. The parameters of release and permeability through the pig skin of the active substances contained in the obtained semi-solid formulations were determined. The results indicate that an emulsion-based gel enhanced the skin penetration of IBU and its derivatives compared to two commercial preparations in the form of a gel and a cream. The average cumulative mass of IBU after a 24 h permeation test from an emulsion-based gel formulation through human skin was 1.6-4.0 times higher than for the commercial products. Ibuprofen derivatives were evaluated as chemical penetration enhancers. After 24 h of penetration, the cumulative mass was 1086.6 ± 245.8 for IBUNa and 948.6 ± 87.5 µg IBU/cm² for [PheOEt][IBU], respectively. This study demonstrates the perspective of the transdermal emulsion-based gel vehicle in conjunction with the modification of the drug as a potentially faster drug delivery system.

Effect of Hydrogel Substrate Components on the Stability of Tetracycline Hydrochloride and Swelling Activity against Model Skin Sebum

Due to its high instability and rapid degradation under adverse conditions, tetracycline hydrochloride (TC) can cause difficulties in the development of an effective but stable formulation for the topical treatment of acne. The aim of the following work was to propose a hydrogel formulation that would ensure the stability of the antibiotic contained in it. Additionally, an important property of the prepared formulations was the activity of the alcoholamines contained in them against the components of the model sebum. This feature may help effectively cleanse the hair follicles in the accumulated sebum layer. A series of formulations with varying proportions of anionic polymer and alcoholamine and containing different polymers have been developed. The stability of tetracycline hydrochloride contained in the hydrogels was evaluated for 28 days by HPLC analysis. Formulations containing a large excess of TRIS alcoholamine led to the rapid degradation of TC from an initial concentration of about 10 µg/mL to about 1 µg/mL after 28 days. At the same time, these formulations showed the highest activity against artificial sebum components. Thanks to appropriately selected proportions of the components, it was possible to develop a formulation that assured the stability of tetracycline for ca. one month, while maintaining formulation activity against the components of model sebum.

An inventory of adjuvants used for vaccination in horses: the past, the present and the future

Vaccination is one of the most widely used strategies to protect horses against pathogens. However, available equine vaccines often have limitations, as they do not always provide effective, long-term protection and booster injections are often required. In addition, research efforts are needed to develop effective vaccines against emerging equine pathogens. In this review, we provide an inventory of approved adjuvants for equine vaccines worldwide, and discuss their composition and mode of action when available. A wide range of adjuvants are used in marketed vaccines for horses, the main families being aluminium salts, emulsions, polymers, saponins and ISCOMs. We also present veterinary adjuvants that are already used for vaccination in other species and are currently evaluated in horses to improve equine vaccination and to meet the expected level of protection against pathogens in the equine industry. Finally, we discuss new adjuvants such as liposomes, polylactic acid polymers, inulin, poly-ε-caprolactone nanoparticles and co-polymers that are in development. Our objective is to help professionals in the horse industry understand the composition of marketed equine vaccines in a context of mistrust towards vaccines. Besides, this review provides researchers with a list of adjuvants, either approved or at least evaluated in horses, that could be used either alone or in combination to develop new vaccines.

[Use of dexpanthenol in corneal damage]

Issues of regeneration of the cornea, which is the most vulnerable structure of the eyeball, suffering from various diseases and injuries, burns, when wearing contact lenses and glaucoma, are highly relevant for ophthalmologists. It is also necessary to minimize damage and stimulate corneal epithelization during and after the use of steroidal and non-steroidal anti-inflammatory drugs, antibacterial drugs and antiseptics, which have a cytotoxic effect and often inhibit regeneration processes, potentially even leading to the development of corneal epithelial defects. This review analyzes the effectiveness of a promising drug 5% dexpanthenol in terms of improving the reparative processes and the function of epithelial cells.

Short- and long-term effects of a multi-component, artificial tear on preocular tear film stability, tear evaporation and tear film optical dynamic: a prospective randomized double-phase study

AIM

To evaluate the short- (within 90 minutes) and long-term (after 21 days of treatment) effects of an artificial tear containing carbomer, hyaluronic acid, glycerol, and medium-chain triglycerides in patients with mild-to-moderate dry eye symptoms.

PATIENTS AND METHODS

Subjects received the tested artificial tears in the right eye and control artificial tears in the left eye and were assessed 10, 30, 60, and 90 minutes after instillation in the short-term study phase. They received the study product in both eyes in the long-term phase. Non-invasive break-up time (NIBUT), tear lipid layer pattern, tear evaporation, and tear film objective optical dynamics (TFOOD) were measured in controlled environmental conditions.

RESULTS

In total, 32 patients (10 males, mean age 42 ± 11 years) were enrolled. During the short-term phase, NIBUT increased significantly in the right eyes at all time points compared with baseline (all p < 0.05). Conversely, in the left eyes, NIBUT increased significantly at 10 and 30 min (p < 0.05). The tear evaporation values increased at 10 minutes and decreased at 30 and 60 minutes (p < 0.05) in the right eyes, while they increased only at 10 minutes (p < 0.05) in the left eyes. Compared with baseline, the TFOOD was significantly more stable at all time points in the right eyes (p < 0.05), while it was more stable at 10 and 30 min in the left eyes (p < 0.05). In the long-term phase, treated eyes showed a significant increase in NIBUT values, a significant reduction of tear evaporation, a significant improvement of tear lipid layer pattern, and a more stable TFOOD compared with baseline (all p < 0.05). Symptoms, measured with the Ocular Surface Disease Index questionnaire, were also significantly reduced compared with baseline (p < 0.05).

CONCLUSION

The tested product increased tear film stability and reduced tear evaporation, normalizing lipid layer pattern and reducing symptoms in the short- and long-term observation.

Safety evaluation of crosslinked polyacrylic acid polymers (carbomer) as a new food additive

The EFSA Panel on Food Additives and Flavourings (FAF) provides a scientific opinion on the safety of crosslinked polyacrylic acid polymers (carbomer) proposed for use as food additive in solid and liquid food supplements. Carbomer is formed from the monomer, acrylic acid, which is polymerised and crosslinked with allyl pentaerythritol (APE). The polymers are synthesised in ethyl acetate using ■■■■■ as free-radical polymerisation initiator. In vivo data showed no evidence for systemic availability or biotransformation of carbomer. Carbomer does not raise a concern regarding genotoxicity. Considering the available data set, the Panel derived an acceptable daily intake (ADI) of 190 mg/kg body weight (bw) per day based on a no observed adverse effect level (NOAEL) of 1,500 mg/kg bw per day from a sub-chronic 13-week study in rat, applying a compound specific uncertainty factor (UF) of 8. At the proposed maximum use levels, the exposure estimates ranged at the mean from 1.1 to 90.2 mg/kg bw per day and at the p95 from 12.5 to 237.4 mg/kg bw per day. At the proposed typical use level, the exposure estimates ranged at the mean from 0.7 to 60.2 mg/kg bw per day and at the p95 from 10.3 to 159.5 mg/kg bw per day. The Panel noted that the maximum proposed use levels would result in exposure estimates close to or above the ADI. The Panel also noted that level of exposure to carbomer from its proposed use is likely to be an overestimation. Taking a conservative approach, the Panel considered that exposure to carbomer would not give rise to a safety concern if the proposed maximum use level for solid food supplements is lowered to the typical use level reported by the applicant.

Microemulsions as Solubilizers and Penetration Enhancers for Minoxidil Release from Gels

Micro- and nanoemulsions are potential drug solubilizers and penetration enhancers through the high surfactant/co-surfactant content. This study aimed to evaluate the influence of minoxidil (MXD) solubilized in the microemulsions (MEs) on drug release by in vitro/ex vivo diffusion through the semi-permeable membrane Spectra/Por^® (Spectrum Laboratory, Gardena, CA, USA) and porcine ear skin. Moreover, a residual amount of drug in the skin after ex vivo diffusion was evaluated. The reference ME_R, lecithin-containing ME_L, and gelatin-containing ME_G were characterized in terms of their size, polydispersity index, density, viscosity, electrical conductivity and surface tension. Based on the in vitro diffusion, it can be argued that ME_L slowed down the drug release, while ME_R and ME_G have no significant effect compared to the sample, in which propylene glycol (PG) was used as a solubilizer. Determination of the residual drug amount in the skin after 6 h of the ex vivo permeation was demonstrated as the most valuable method to evaluate the effectiveness of the ME’s application. The results indicate that the most optimal MXD permeation enhancers in alginate gel were the natural surfactants containing MEs. MXD solubilization in ME_G and ME_L had caused more than 5% of the drug remaining in the skin, which is almost a 1.5-fold higher amount compared to the reference gel.

Enhancing Electrical Contact with a Commercial Polymer for Electrical Resistivity Tomography on Archaeological Sites: A Case Study

This communication reports an improvement of the quality of the electrical data obtained from the application of electrical resistivity tomography method on archaeological studies. The electrical contact between ground and electrode enhances significantly by using carbomer-based gel during the electrical resistivity tomography measurements. Not only does the gel promote the conservation of the building surface under investigation, but it also virtually eliminates the necessity of conventional spike electrodes, which in many archaeological studies are inadequate or not permitted. Results evidenced an enhancement in the quality of the electrical data obtained in the order of thousands of units compared with those without using the carbomer-based gel. The potential and capabilities of this affordable gel make it appropriate to be applied to other geoelectrical studies beyond archaeological investigations. Moreover, it might solve corrosion issues on conventional spike electrodes, and electrical multicore cables usually provoked for added saltwater attempting to improve the electrical contact.

Hydrogel Containing Oleoresin From Copaifera officinalis Presents Antibacterial Activity Against Streptococcus agalactiae

Streptococcus agalactiae or Group B Streptococcus (GBS) remains a leading cause of neonatal infections worldwide; and the maternal vaginal-rectal colonization increases the risk of vertical transmission of GBS to neonates and development of infections. This study reports the in vitro antibacterial effect of the oleoresin from Copaifera officinalis Jacq. L. in natura (copaiba oil) and loaded into carbomer-hydrogel against planktonic and sessile cells of GBS. First, the naturally extracted copaiba oil was tested for the ability to inhibit the growth and metabolic activity of planktonic and sessile GBS cells. The time-kill kinetics showed that copaiba oil exhibited a dose-dependent bactericidal activity against planktonic GBS strains, including those resistant to erythromycin and/or clindamycin [minimal bactericidal concentration (MBC) ranged from 0.06 mg/mL to 0.12 mg/mL]. Copaiba oil did not inhibit the growth of different Lactobacillus species, the indigenous members of the human microbiota. The mass spectral analyses of copaiba oil showed the presence of diterpenes, and the kaurenoic acid appears to be one of the active components of oleoresin from C. officinalis related to antibacterial activity against GBS. Microscopy analyses of planktonic GBS cells treated with copaiba oil revealed morphological and ultrastructural alterations, displaying disruption of the cell wall, damaged cell membrane, decreased electron density of the cytoplasm, presence of intracellular condensed material, and asymmetric septa. Copaiba oil also exhibited antibacterial activity against established biofilms of GBS strains, inhibiting the viability of sessile cells. Low-cost and eco-friendly carbomer-based hydrogels containing copaiba oil (0.5% – CARB-CO 0.5; 1.0% – CARB-CO 1.0) were then developed. However, only CARB-CO 1.0 preserved the antibacterial activity of copaiba oil against GBS strains. This formulation was homogeneous, soft, exhibited a viscoelastic behavior, and showed good biocompatibility with murine vaginal mucosa. Moreover, CARB-CO 1.0 showed a slow and sustained release of the copaiba oil, killing the planktonic and sessile (established biofilm) cells and inhibiting the biofilm formation of GBS on pre-coated abiotic surface. These results indicate that carbomer-based hydrogels may be useful as topical systems for delivery of copaiba oil directly into de vaginal mucosa and controlling S. agalactiae colonization and infection.

Comprehensive review of the role of acrylic acid derivative polymers in floating drug delivery system

In the development of drug delivery systems, an oral drug delivery system is the preferred route of drug administration. Many components play an important role in developing a drug delivery system. Amongst those components, polymers have evolved with these systems. Macromolecule compounds consisting of many monomer units which are joined to each other by different bonds are known as polymers. For drugs that are absorbed primarily in the upper gastrointestinal tract, floating drug delivery systems offer an additional advantage. The purpose behind this review was to focus on different types of floating drug delivery systems and different types of polymers used in floating drug delivery systems, focusing on acrylic acid derivatives and their applications. In this review, the main emphasis is on acrylic acid derivative polymers, their formulation and grades, and various patents on these types of polymers. Based on the literature survey, mainly 2 types of polymers are used in this drug delivery system; i.e., natural and synthetic. Examples of natural polymers are xanthan gum, guar gum or chitosan, and synthetic polymers include acrylic acid derivatives and hydroxylpropyl methylcellulose (HPMC). Eudragit and Carbopol are the most widely used acrylic acid derivatives.

Investigation of Migration-Preventing Tracheal Stent with High Dose of 5-Fluorouracil or Paclitaxel for Local Drug Delivery

Stent migration is one of the common reasons for the failure of tracheal stent. An antitumor drug/tracheal stent combination can promptly relieve dyspnea caused by tracheal stenosis and locally treat malignant occupying lesion or tumor. To prevent stent migration for more effective treatment, we prepared a migration-preventing nitinol tracheal stent (TS) with a high dose of 5-fluorouracil or paclitaxel (5-FU/TS or PTX/TS) by stent surface coating with a bilayered film, which is composed of a drug-loaded layer containing Carbopol 974P as mucoadhesive matrix and a blank Carbopol 974P layer. The resulting stent had a similar mechanical performance with the nitinol tracheal stent itself. The bilayered film containing 30% PTX (PTX30) could keep adhesion to porcine mucosa for 221.7 ± 11.4 min in PBS at a stirring speed of 150 rpm, and the corresponding PTX30/TS was difficult to be moved in the porcine tracheal lumen with a pulling force less than 0.7 N, indicating its good migration-preventing ability. The migration-preventing ability of the 5-FU/TS or PTX/TS was related to the compositions of bilayered films. The 5-FU release from the 5-FU/TS was dominated by a relaxation mechanism, while the PTX release was mainly controlled by a diffusion mechanism. Moreover, the 5-FU permeation from the 5-FU loaded film through the porcine tracheal mucosa was determined by the 5-FU dissolution, and PTX permeation was limited by the trans-mucosa process. After the deployment of PTX30/TS, inflammatory responses were observed in the rabbit tracheas and gradually alleviated during the follow-up period.

Developing Transdermal Applications of Ketorolac Tromethamine Entrapped in Stimuli Sensitive Block Copolymer Hydrogels

PURPOSE

In order to obtain dermal vehicles of ketorolac tromethamine (KT) for the local treatment of inflammation and restrict undesirable side effects of systemic levels hydrogels (HGs) of poloxamer and carbomer were developed.

METHODS

KT poloxamer based HG (KT-P407-HG) and KT carbomer based HG (KT-C940-HG) were elaborated and characterized in terms of swelling, degradation, porosity, rheology, stability, in vitro release, ex vivo permeation and distribution skin layers. Finally, in vivo anti-inflammatory efficacy and skin tolerance were also assessed.

RESULTS

HGs were transparent and kept stable after 3 months exhibiting biocompatible near neutral pH values. Rheological patterns fitted to Herschel-Bulkley for KT-C940-HG and Newton for KT-P407-HG due to its low viscosity at 25°C. Rapid release profiles were observed through first order kinetics. Following the surface the highest concentration of KT from C940-HG was found in the epidermis and the stratum corneum for P407-HG. Relevant anti-inflammatory efficacy of KT-P407-HG revealed enough ability to provide sufficient bioavailability KT to reach easily the site of action. The application of developed formulations in volunteers did not induce any visual skin irritation.

CONCLUSIONS

KT-P407-HG was proposed as suitable formulation for anti-inflammatory local treatment without theoretical systemic side effect.

Designed drug-release systems having various breathable polyurethane film-backed hydrocolloid acrylated adhesive layers for moisture healing

A series of designed drug-release systems were prepared and established for clear moisture healing. These systems were designed to have an interpenetrating polymer network (IPN) structure, which contained a breathable polyurethane film, hydrocolloidlayer, and polyacrylate adhesive layer. Breathable polyurethane film (2000 g/m(2)/24 hr) with high moisture permeability was employed as a base for new drug-release systems or wound dressings. All drug-release systems having a polyurethane film-backed hydrocolloid acrylated adhesive layer showed an increase of water uptakes with increasing time. After 114 hours, high water uptakes of drug-release systems with 20% hydrocolloid components were observed in the values of 160, 1100, and 1870% for different additional hydrocolloid components of carboxymethylcellulose, sodium alginate, and carbomer U10, respectively. New drug-release systems of polyurethane film-backed hydrocolloid/adhesive layers could be designed and established for wound care managements.