Rheological and mechanical properties of poloxamer mixtures as a mucoadhesive gel base

A mucoadhesive-to-penetrating nanomotors-in-hydrogel system for urothelium-oriented intravesical drug delivery

Intravesical therapy (IT) is widely used to tackle various urological diseases. However, its clinical efficacy is decreased by the impermeability of various barriers presented on the bladder luminal surface, including the urinary mucus layer and the densely packed tissue barrier. In this study, we report a mucoadhesive-to-penetrating nanomotors-in-hydrogel system for urothelium-oriented intravesical drug delivery. Upon intravesical instillation, its poloxamer 407 (PLX) hydrogel gelated and adhered to the urothelium to prolong its intravesical retention. The urea afterwards diffused into the hydrogel, thus generating a concentration gradient. Urease-powered membrane nanomotors (UMN) without asymmetric surface engineering could catalyze the urea and migrate down this concentration gradient to deeply and unidirectionally penetrate the urothelial barrier. Moreover, the intravesical hybrid system-delivered gemcitabine could effectively inhibit the bladder tumor growth without inducing any side effect. Therefore, our mucoadhesive-to-penetrating nanomotors-in-hydrogel system could serve as an alternative to IT to meet the clinical need for more efficacious therapeutics for urological diseases.

Ultrasound and x-ray imageable poloxamer-based hydrogel for loco-regional therapy delivery in the liver

Intratumoral injections have the potential for enhanced cancer treatment efficacy while reducing costs and systemic exposure. However, intratumoral drug injections can result in substantial off-target leakage and are invisible under standard imaging modalities like ultrasound (US) and x-ray. A thermosensitive poloxamer-based gel for drug delivery was developed that is visible using x-ray imaging (computed tomography (CT), cone beam CT, fluoroscopy), as well as using US by means of integrating perfluorobutane-filled microbubbles (MBs). MBs content was optimized using tissue mimicking phantoms and ex vivo bovine livers. Gel formulations less than 1% MBs provided gel depositions that were clearly identifiable on US and distinguishable from tissue background and with minimal acoustic artifacts. The cross-sectional areas of gel depositions obtained with US and CT imaging were similar in studies using ex vivo bovine liver and postmortem in situ swine liver. The gel formulation enhanced multimodal image-guided navigation, enabling fusion of ultrasound and x-ray/CT imaging, which may enhance targeting, definition of spatial delivery, and overlap of tumor and gel. Although speculative, such a paradigm for intratumoral drug delivery might streamline clinical workflows, reduce radiation exposure by reliance on US, and boost the precision and accuracy of drug delivery targeting during procedures. Imageable gels may also provide enhanced temporal and spatial control of intratumoral conformal drug delivery.

Enhancement of skin localization of β-carotene from red fruit (Pandanus conoideus Lam.) using solid dispersion-thermoresponsive gel delivered via polymeric solid microneedles

Red fruit (Pandanus conoideus Lam.) boasts high β-carotene (BC) content, often consumed orally. However, absorption issues and low bioavailability due to food matrix interaction have led to transdermal delivery exploration. Nevertheless, BC has a short skin retention time. To address these limitations, this study formulates a β-carotene solid dispersion (SD-BC) loaded thermoresponsive gel combined with polymeric solid microneedles (PSM) to enhance in vivo skin bioavailability. Characterization of SD-BC includes saturation solubility, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and in vitro release. Characterization of SD-BC thermoresponsive gel includes gelation temperature, viscosity, rheological behaviour, pH, bio-adhesiveness, spreadability, and extrudability. PSM's mechanical properties and insertion capability were assessed. Ex vivo and in vivo dermato-pharmacokinetic studies, drug content, hemolysis, and skin irritation assessments were conducted to evaluate overall performance. Results confirm amorphous SD-BC formation, enhancing solubility. Both SD-BC thermoresponsive gel and PSM exhibit favourable characteristics, including rheological properties and mechanical strength. In vitro release studies showed a seven-fold increase in BC release compared to plain hydrogel. SD-BC thermoresponsive gel combined with PSM achieves superior ex vivo permeation (Cmax = 305.43 ± 32.07 µg.mL-1) and enhances in vivo dermato-pharmacokinetic parameters by 200-400 %. Drug content, hemolysis, and skin irritation studies confirmed its safety and non-toxicity.

A review on revolutionizing ophthalmic therapy: Unveiling the potential of chitosan, hyaluronic acid, cellulose, cyclodextrin, and poloxamer in eye disease treatments

Ocular disorders, encompassing both common ailments like dry eye syndrome and more severe situations for instance age-related macular degeneration, present significant challenges to effective treatment due to the intricate architecture and physiological barriers of the eye. Polysaccharides are emerging as potential solutions for drug delivery to the eyes due to their compatibility with living organisms, natural biodegradability, and adhesive properties. In this review, we explore not only the recent advancements in polysaccharide-based technologies and their transformative potential in treating ocular illnesses, offering renewed optimism for both patients and professionals but also anatomy of the eye and the significant obstacles hindering drug transportation, followed by an investigation into various drug administration methods and their ability to overcome ocular-specific challenges. Our focus lies on biological adhesive polymers, including chitosan, hyaluronic acid, cellulose, cyclodextrin, and poloxamer, known for their adhesive characteristics enhancing drug retention on ocular surfaces and increasing bioavailability. A detailed analysis of material designs used in ophthalmic formulations, such as gels, lenses, eye drops, nanofibers, microneedles, microspheres, and nanoparticles, their advantages and limitations, the potential of formulations in improving therapeutic outcomes for various eye conditions. Moreover, we underscore the discovery of novel polysaccharides and their potential uses in ocular drug delivery.

X-ray imageable, drug-loaded hydrogel that forms at body temperature for image-guided, needle-based locoregional drug delivery

Liver cancer ranks as the fifth leading cause of cancer-related death globally. Direct intratumoral injections of anti-cancer therapeutics may improve therapeutic efficacy and mitigate adverse effects compared to intravenous injections. Some challenges of intratumoral injections are that the liquid drug formulation may not remain localized and have unpredictable volumetric distribution. Thus, drug delivery varies widely, highly-dependent upon technique. An X-ray imageable poloxamer 407 (POL)-based drug delivery gel was developed and characterized, enabling real-time feedback. Utilizing three needle devices, POL or a control iodinated contrast solution were injected into an ex vivo bovine liver. The 3D distribution was assessed with cone beam computed tomography (CBCT). The 3D distribution of POL gels demonstrated localized spherical morphologies regardless of the injection rate. In addition, the gel 3D conformal distribution could be intentionally altered, depending on the injection technique. When doxorubicin (DOX) was loaded into the POL and injected, DOX distribution on optical imaging matched iodine distribution on CBCT suggesting spatial alignment of DOX and iodine localization in tissue. The controllability and localized deposition of this formulation may ultimately reduce the dependence on operator technique, reduce systemic side effects, and facilitate reproducibility across treatments, through more predictable standardized delivery.

Encapsulation of the growth factor neurotrophin-3 in heparinised poloxamer hydrogel stabilises bioactivity and provides sustained release

Poloxamer-based hydrogels show promise to stabilise and sustain the delivery of growth factors in tissue engineering applications, such as following spinal cord injury. Typically, growth factors such as neurotrophin-3 (NT-3) degrade rapidly in solution. Similarly, poloxamer hydrogels also degrade readily and are, therefore, only capable of sustaining the release of a payload over a small number of days. In this study, we focused on optimising a hydrogel formulation, incorporating both poloxamer 188 and 407, for the sustained delivery of bioactive NT-3. Hyaluronic acid blended into the hydrogels significantly reduced the degradation of the gel. We identified an optimal hydrogel composition consisting of 20 % w/w poloxamer 407, 5 % w/w poloxamer 188, 0.6 % w/w NaCl, and 1.5 % w/w hyaluronic acid. Heparin was chemically bound to the poloxamer chains to enhance interactions between the hydrogel and the growth factor. The unmodified and heparin-modified hydrogels exhibited sustained release of NT-3 for 28 days while preserving the bioactivity of NT-3. Moreover, these hydrogels demonstrated excellent cytocompatibility and had properties suitable for injection into the intrathecal space, underscoring their suitability as a growth factor delivery system. The findings presented here contribute valuable insights to the development of effective delivery strategies for therapeutic growth factors for tissue engineering approaches, including the treatment of spinal cord injury.

Phase transforming in situ gels for sustained and controlled transmucosal drug delivery via the intravaginal route

Direct, reliable, controlled, and sustained drug delivery to female reproductive tract (FRT) remains elusive, with conventional dosage forms falling way short of the mark, leading to premature leakage, erratic drug delivery, and loss of compliance. Historically, the intravaginal route remains underserved by the pharmaceutical sector. To comprehensively address this, we turned our focus to phase-transforming sol-gels, using poloxamers, a thermosensitive polymer and, doxycycline (as hyclate salt, DOXH) as our model agent given its potential use in sexually transmitted infections (STIs). We further enhanced mucoadhesiveness through screening of differing viscosity grade hydroxypropyl methyl celluloses (HPMCs). The optimised sol-gels remained gelled at body temperature (<37 °C) and were prepared in buffer aligned to vaginal cavity pH and osmolality. Lead formulations were progressed based on their ability to retain key rheological properties, and acidic pH in the presence of simulated vaginal fluid (SVF). From a shelf-life perspective, DOXH stability, gelation temperature (Tsol-gel), and pH to three months (2-8 °C) was attained. In summary, the meticulously engineered, phase-transforming sol-gels provided sustained mucoretention despite dilution by vaginal fluid, paving the way for localised antimicrobial drug delivery at concentrations that potentially far exceed the minimum inhibitory concentration (MIC) for target STI-causing bacteria of the FRT.

Development and Characterization of Thermosensitive and Bioadhesive Ophthalmic Formulations Containing Flurbiprofen Solid Dispersions

In this study, we aimed to develop thermosensitive and bioadhesive in situ gelling systems containing solid dispersions of flurbiprofen (FB-SDs) using poloxamer 407 (P407) and 188 (P188) for ophthalmic delivery. FB-SDs were prepared with the melt method using P407, characterized by solubility, stability, SEM, DSC, TGA, and XRD analyses. Various formulations of poloxamer mixtures and FB-SDs were prepared using the cold method and P407/P188 (15/26.5%), which gels between 32 and 35 °C, was selected to develop an ophthalmic in situ gelling system. Bioadhesive polymers Carbopol 934P (CP) or carboxymethyl cellulose (CMC) were added in three concentrations (0.2, 0.4, and 0.6% (w/w)). Gelation temperature and time, mechanical properties, flow properties, and viscosity values were determined. The in vitro release rate, release kinetics, and the release mechanism of flurbiprofen (FB) from the ophthalmic formulations were analyzed. The results showed that FB-SDs' solubility in water increased 332-fold compared with FB. The oscillation study results indicated that increasing bioadhesive polymer concentrations decreased gelation temperature and time, and formulations containing CP gel at lower temperatures and in a shorter time. All formulations except F3 and F4 showed Newtonion flow under non-physiological conditions, while all formulations exhibited non-Newtonion pseudoplastic flow under physiological conditions. Viscosity values increased with an increase in bioadhesive polymer concertation at physiological conditions. Texture profile analysis (TPA) showed that CP-containing formulations had higher hardness, compressibility, and adhesiveness, and the gel structure of formulation F4, containing 0.6% CP, exhibited the greatest hardness, compressibility, and adhesiveness. In vitro drug release studies indicated that CP and CMC had no effect below 0.6% concentration. Kinetic evaluation favored first-order and Hixson-Crowell kinetic models. Release mechanism analysis showed that the n values of the formulations were greater than 1 except for formulation F5, suggesting that FB might be released from the ophthalmic formulations by super case II type diffusion. When all the results of this study are evaluated, the in situ gelling formulations prepared with FB-SDs that contained P407/P188 (15/26.5%) and 0.2% CP or 0.2% CMC or 0.4 CMC% (F2, F5, and F6, respectively) could be promising formulations to prolong precorneal residence time and improve ocular bioavailability of FB.

Formulation of Metoclopramide Hydrochloride-Loaded Lipid Carriers by QbD Approach for Combating Nausea: Safety and Bioavailability Evaluation in New Zealand Rabbit

The focus of the research was to overcome the limitations of metoclopramide (MTC) when administered intranasally. The aim was to improve its bioavailability, increase patient compliance, and prolong its residence time in the nasal cavity. MTC-loaded liposomes were prepared by applying the film hydration method. A study was conducted to determine how formulation variables affected encapsulation efficiency (EE %), mean particle size (MPS), and zeta potential (ZP). The MTC-liposomes were further loaded into the in situ gel (gellan gum) for longer residence times following intranasal administration. pH, gelling time, and in vitro release tests were conducted on the formulations produced. In vivo performance of the MTC-loaded in situ gels was appraised based on disparate parameters such as plasma peak concentration, plasma peak time, and elimination coefficient compared to intravenous administration. When the optimal liposome formulation contained 1.98% of SPC, 0.081% of cholesterol, 97.84% of chloroform, and 0.1% of MTC, the EE of MTC was 83.21%, PS was 107.3 nm. After 5 h, more than 80% of the drug was released from MTC-loaded liposome incorporated into gellan gum in situ gel formulation (Lip-GG), which exhibited improved absorption and higher bioavailability compared to MTC loaded into gellan gum in situ gel (MTC-GG). Acceptable cell viability was also achieved. It was found out that MTC-loaded liposomal in situ gel formulations administered through the nasal route could be a better choice than other options due to its ease of administration, accurate dosing, and higher bioavailability in comparison with MTC-GG.

Development of nanostructured environmentally responsive system containing hydroxypropyl methylcellulose for nose-to-brain administration of meloxicam

The intranasal administration of drugs using environmentally responsive formulations, employing a combination of hydroxypropyl methylcellulose (HPMC) and poloxamer 407 (P407), can result in release systems that may assist in the treatment of neurological diseases. Meloxicam, considered a potential adjuvant in the treatment of Alzheimer's disease, could be used in these platforms. The aim of this work was to develop a mucoadhesive, thermoresponsive, and nanostructured system containing HPMC for nose-to-brain administration of meloxicam. The initially selected systems were investigated for their rheological, mechanical, and micellar size characteristics. The systems were dilatant at 25 °C and pseudoplastic with a yield value at 37 °C, showing viscoelastic properties at both temperatures. The platform containing HPMC (0.1%, w/w) and P407 (17.5%, w/w) was selected and demonstrated good mucoadhesive properties, along with an appropriate in vitro release profile. HPMC could form a binary system with P407, displaying superior mucoadhesive and thermoresponsive properties for nose-to-brain meloxicam administration, indicating that the selected formulation is worthy of clinical studies.

Preparation of Tamsulosin Hydrochloride-Loaded Mucoadhesive In Situ Gelling Polymeric Formulation for Nasal Delivery in Geriatrics

This study aimed to prepare tamsulosin hydrochloride (HCl)-loaded in situ gelling formulation by using hydroxypropyl methylcellulose (HPMC), gellan gum, poloxamer 188, and benzalkonium chloride. Physicochemical evaluation of formulations included determination of pH, viscosity, gelation time, gel strength, drug content, and sterility. In silico study was performed to analyze interactions between polymers, drug, and mucin glycoprotein. In vitro degradation time, drug release, ex vivo mucoadhesion time, permeation, in vivo pharmacokinetics, and stability studies were performed to assess the formulation. Formulations were transparent and displayed acceptable physicochemical attributes. Tamsulosin HCl and polymers interacted via non-covalent interactions. HPMC formed hydrogen bonds, hydrophobic and van der Waals interactions with mucin protein while the drug formed hydrogen bonds only. Gel formulation degraded in simulated nasal fluid within 24 h. In situ gelling formulation showed 83.8 ± 1.7% drug release and remained adhered to the mucosa for 24.5 ± 1 h. A higher (~ 1.85 times) drug permeation was recorded through mucosa within 6 h by in situ gelling formulation when compared to control counterparts (aqueous solution of drug and in situ gelling formulation without poloxamer 188). Nasal administration of tamsulosin HCl by using in situ gelling formulation led to a ~ 3.3 and ~ 3.5 times, respectively, higher Cmax (maximum plasma concentration) and AUCtotal (total area under the curve) than the orally administered aqueous solution. Relative bioavailability of drug delivered by nasal in situ gelling formulation was 3.5 times the oral counterpart. These results indicated that the prepared in situ gelling formulation can act as a promising candidate for systemic administration of tamsulosin HCl.

Development and characterization of a poloxamer hydrogel composed of human mesenchymal stromal cells (hMSCs) for reepithelization of skin injuries

Wound healing is a natural physiological reaction to tissue injury. Hydrogels show attractive advantages in wound healing not only due to their biodegradability, biocompatibility and permeability but also because provide an excellent environment for cell migration and proliferation. The main objective of the present study was the design and characterization of a hydrogel loaded with human mesenchymal stromal cells (hMSCs) for use in would healing of superficial skin injures. Poloxamer 407® was used as biocompatible biomaterial to embed hMSCs. The developed hydrogel containing 20 % (w/w) of polymer resulted in the best formulation with respect to physical, mechanical, morphological and biological properties. Its high swelling capacity confirmed the hydrogel's capacity to absorb wounds' exudate. LIVE/DEAD® assay confirm that hMSCs remained viable for at least 48 h when loaded into the hydrogels. Adding increasing concentrations of hMSCs-loaded hydrogel to the epithelium did not affect keratinocytes' viability and healing capacity and all wound area was closed in less than one day. Our study opens opportunities to exploit poloxamer hydrogels as cell carriers for the treatment of skin superficial wound.

Liposomal and Ethosomal Gels: From Design to Application

The use of lipid-based nanosystems for topical administration represents an innovative "green" approach, being composed of materials, defined as GRAS (generally recognized as safe), characterized by low toxicity, biocompatibility, and biodegradability [...].

Novel Sprayable Thermosensitive Benzydamine Hydrogels for Topical Application: Development, Characterization, and In Vitro Biological Activities

Benzydamine hydrochloride (BZD) having analgesic, anesthetic, and anti-inflammatory effects is used orally or topically in the treatment of disorders such as joint inflammation and muscle pain. Within the scope of this study, sprayable thermosensitive BZD hydrogels were developed using thermoresponsive poloxamers to avoid systemic side effects and to provide better compliance for topical administration. Also, hydroxypropyl methyl cellulose (HPMC) was employed to improve the mechanical strength and bioadhesive properties of the hydrogel. The addition of BZD generally decreased the viscosity of the formulations (p < 0.05), while increasing the gelation temperature (p < 0.05). The formulations that did not have any clogs or leaks in the nozzle of the bottle during the spraying process were considered lead formulations. To spray the formulations easily, it was found that the viscosity at RT should be less than 200 mPa·s, and their gelation temperature should be between 26 and 34°C. Increasing HPMC and poloxamer improved bioadhesion. The amount of HPMC and poloxamers did not cause a significant change in the release characteristics of the formulations (p > 0.05); the release profiles of BZD from the formulations were similar according to model-independent kinetic (f2 > 50). HPMC and poloxamers had important roles in the accumulation of BZD in the skin. In vitro biological activity studies demonstrated that the formulations presented their anti-inflammatory activity with TNF-α inhibition but did not have any effect on the inhibition of COX enzymes as expected. As a result, thermosensitive hydrogels containing BZD might be an appropriate alternative, providing an advantage in terms of easier application compared to conventional gels.

In situ hydrogel containing diazepam-loaded nanostructured lipid carriers (DZP-NLC) for nose-to-brain delivery: development, characterization and deposition studies in a 3D-printed human nasal cavity model

The nasal route has been investigated as a promising alternative for drug delivery to the central nervous system, avoiding passage through the blood-brain barrier and improving bioavailability. In this sense, it is necessary to develop and test the effectiveness of new formulations proposed for the management of neurological disorders. Thereby, the aim of this work was to develop and characterize an ion sensitive in situ hydrogel containing diazepam-loaded nanostructured lipid carriers (DZP-NLC) for nasal delivery in the treatment of epilepsy. Physical characterization of the developed formulations was performed and included the evaluation of rheological features, particle size, polydispersity index (PDI) and zeta potential (ZP) of an in situ hydrogel containing DZP-NLC. Afterwards, in vitro drug release, in vitro mucoadhesion and biocompatibility studies with RPMI 2650 nasal cells were performed. The in situ hydrogel containing DZP-NLC was aerosolized with a nasal spray device specifically designed for nose-to-brain delivery (VP7 multidose spray pump with a 232 N2B actuator) and characterized for droplet size distribution and spray cone angle. Finally, the deposition pattern of this hydrogel was evaluated in a 3D-printed human nasal cavity model. The developed in situ hydrogel containing DZP-NLC presented adequate characteristics for nasal administration, including good gelling ability, mucoadhesiveness and prolonged drug release. In addition, after inclusion in the hydrogel net, the particle size (81.79 ± 0.53 nm), PDI (0.21 ± 0.10) and ZP (-30.90 ± 0.10 mV), of the DZP-NLC remained appropriate for nose-to-brain delivery. Upon aerosolization in a nasal spray device, a suitable spray cone angle (22.5 ± 0.2°) and adequate droplet size distribution (Dv (90) of 317.77 ± 44.12 µm) were observed. Biocompatibility studies have shown that the developed formulation is safe towards RPMI 2650 cells in concentrations up to 100 μg/mL. Deposition studies on a 3D-printed human nasal cavity model revealed that the best nasal deposition profile was obtained upon formulation administration without airflow and at an angle from horizontal plane of 75°, resulting in 47% of administered dose deposited in the olfactory region and 89% recovery. The results of this study suggested that the intranasal administration of the developed in situ hydrogel containing DZP-NLC could be a promising alternative to the conventional treatments for epilepsy.

Boosting the photodynamic activity of erythrosine B by using thermoresponsive and adhesive systems containing cellulose derivatives for topical delivery

Erythrosine displays potential photodynamic activity against microorganisms and unhealthy cells. However, erythrosine has high hydrophilicity, negatively impacting on permeation through biological membranes. Combining biological macromolecules and thermoresponsive polymers may overcome these erythrosine-related issues, enhancing retention of topically applied drugs. The aim of this work was to investigate the performance of adhesive and thermoresponsive micellar polymeric systems, containing erythrosine in neutral (ERI) or disodium salt (ERIs) states. Optimized combinations of poloxamer 407 (polox407) and sodium carboxymethylcellulose (NaCMC) or hydroxypropyl methylcellulose (HPMC) were used as platforms for ERI/ERIs delivery. The rheological and mechanical properties of the systems was explored. Most of the formulations were plastic, thixotropic and viscoelastic at 37 °C, with suitable gelation temperature for in situ gelation. Mechanical parameters were reduced in the presence of the photosensitizer, improving the softness index. Bioadhesion was efficient for all hydrogels, with improved parameters for mucosa in contrast to skin. Formulations composed of 17.5 % polox407 and 3 % HPMC or 1 % NaCMC with 1 % (w/w) ERI/ERIs could release the photosensitizer, reaching different layers of the skin/mucosa, ensuring enough production of cytotoxic species for photodynamic therapy. Functional micelles could boost the photodynamic activity of ERI and ERIs, improving their delivery and contact time with the cells.

Piperine-Loaded In Situ Gel: Formulation, In Vitro Characterization, and Clinical Evaluation against Periodontitis

Periodontitis is an inflammatory disorder associated with dysbiosis and characterized by microbiologically related, host-mediated inflammation that leads to the damage of periodontal tissues including gingiva, connective tissues, and alveolar bone. The aim of this study was to develop an in situ gel consisting of piperine. Eight in situ gel formulations were designed by varying the concentration of deacylated gellan gum cross-linked with sodium tripolyphosphate, and poloxamer-407. The prepared gels were evaluated for gelation temperature, gelation time, viscosity, piperine-loading efficiency, and piperine release. Finally, the optimized formula was evaluated for anti-inflammatory effectiveness among human patients during a 14-day follow-up. The optimized in situ gel formulation exhibited a gelation temperature of 35 ± 1 °C, gelling of 36 ± 1 s, excellent syringeability, and piperine loading of 95.3 ± 2.3%. This formulation efficiently sustained in vitro drug release for up to 72 h. In vivo studies revealed an efficient sol-to-gel transformation of optimized in situ gel formulation at physiological conditions, permitting an efficient residence time of the formulation within a periodontitis pocket. Most importantly, a clinical study revealed that treatment with the optimized formulation elicited a significant reduction in the mean plaque score (p = 0.001), gingival index (p = 0.003), and pocket depth (p = 0.002), and exerted a potent anti-inflammatory potential, compared to the control group. Collectively, piperine-loaded in situ gel might represent a viable therapeutic approach for the management of gingival and periodontal diseases.

Thermoresponsive Gel-loaded Oxcarbazepine Nanosystems for Nose- To-Brain Delivery: Enhanced Antiepileptic Activity in Rats

BACKGROUND

Oxcarbazepine (OXC) is a frequently prescribed antiepileptic drug for managing focal and generalized seizures. Its therapeutic benefits are limited by its dose-dependent side effects. Nose-to-brain delivery is a novel route for improving the efficacy of antiepileptics. Drug encapsulation in mucoadhesive nanoparticles offers even more advantages for the nasal route.

OBJECTIVE

The study aimed to develop oxcarbazepine-loaded chitosan nanoparticles (OXC-NP) added to a mucoadhesive thermo-reversible gel for intranasal delivery and enhancement of antiepileptic activity.

METHODS

The formulation was optimized based on entrapment efficiency, polydispersity index, particle size, zeta potential, and in vitro release analysis. The therapeutic efficacy of OXC-NP was assessed in an epileptic rat model and compared to intranasal OXC and oral OXC.

RESULTS

The optimized OXC-NPs with chitosan exhibited particle size, zeta potential, and entrapment efficiency of 189 nm, + 31.4 mV ± 2.5 and 97.6% ± 0.14, respectively. The release of OXC was prolonged, reaching 47.1% after 6 h and 55% after 24 h. Enhanced antiepileptic activity of OXC-NP was manifested as decreased seizure score and prolonged survival. Halting of hippocampal TNF-α and IL-6 together with upregulated IL-10 could explain its anti-inflammatory mechanisms.

CONCLUSIONS

Intranasal OXC-NP-loaded in situ gel represents a promising formulation for enhanced antiepileptic potential achieved at low drug concentrations.

Intranasal in situ gelling liquid crystal for delivery of resveratrol ameliorates memory and neuroinflammation in Alzheimer's disease

Alzheimer's disease (AD) is an illness that affects people aged 65 or older and affects around 6.5 million in the United States. Resveratrol is a chemical obtained from natural products and it exhibits biological activity based on inhibiting the formation, depolymerization of the amyloid, and decreasing neuroinflammation. Due to the insolubility of this compound; its incorporation in surfactant-based systems was proposed to design an intranasal formulation. A range of systems has been produced by mixing oleic acid, CETETH-20 and water. Polarised light microscopy (PLM), small angle x-ray scattering (SAXS) and transmission electron microscopy (TEM) confirm the initial liquid formulation (F) presented as microemulsion (ME). After dilution, the gelled systems were characterized as hexagonal mesophase and they showed feasibility proprieties. Pharmacological assays performed after intranasal administration showed the ability to improve learning and memory in animals, as well as remission of neuroinflammation via inhibition of interleukin.

Physico-mechanical and ex vivo analysis of aloe-alginate hydrogels for cervical cancer treatment

A leading cancer diagnosis in women worldwide is cervical cancer, with current treatments all posing a risk of serious side effects. Less toxic, but effective treatments are sought after. Aloe vera ( barbadensis miller), known for its beneficial properties, has been studied for cancer treatment. While aloe gel has been shown to exhibit anti-cancer activity, it cannot form a hydrogel alone. Therefore, an interpenetrating network comprising alginate blended with aloe was examined as a cervical cancer treatment. We hypothesized the antioxidant properties of aloe gel would decrease cancer cell viability while the alginate hydrogel would improve mucoadhesion. We further hypothesized the antioxidant activity of aloe gel would induce cancer cell death at levels similar to common chemotherapeutics, and aimed to determine if these chemotherapeutic behaviors are constructive or destructive. Material and adhesive properties, drug encapsulation, and cancer cell viability were investigated and validated. The effect of aloe-alginate hydrogels on cervical cancer cell viability was not significantly different compared to aloe-blends containing doxorubicin (DOX), indicating that the aloe alone decreased cancer cell viability rendering the additional cytotoxic therapeutic not impactful as an adjuvant therapy. This study provides insight into the potential of natural biopolymers for treating cervical cancer without systemic toxic compounds.

Investigating the Targeting Power to Brain Tissues of Intranasal Rasagiline Mesylate-Loaded Transferosomal In Situ Gel for Efficient Treatment of Parkinson's Disease

Rasagiline mesylate (RSM) is a hydrophilic drug with poor oral bioavailability (36%) because of hepatic first-pass metabolism. The present study focuses on delivering RSM directly to the brain through its inclusion within transferosomal in situ gel administered through the intranasal (IN) route. Transferosomes were formed by the thin-film hydration method with the aid of Design-Expert^® software by varying the edge activator (EA) type in the absence or presence of cholesterol. By desirability calculations, the optimum formulation was composed of phosphatidylcholine and sodium deoxycholate as an EA (5:1% w/w) with no cholesterol. The optimum formulation was 198.63 ± 34.98 nm in size and displayed an entrapment efficiency of 95.73 ± 0.09%. Transmission electron microscopy revealed discrete and spherical vesicles. Optimized transferosomes were further incorporated into an in situ gel composed of 0.5% pectin, 15% Pluronic^® F-127, and 5% Pluronic^® F-68 and tested for the in vivo performance. The systemic as well as brain kinetics were assessed in rats by comparing the IN-administered in situ gel to the IV aqueous solution. The optimum in situ gel showed safety and biocompatibility on rats' nasal mucosa with enhanced brain bioavailability (131.17%). Drug targeting efficiency and direct transport percentage indices (304.53% and 67.16%, respectively) supported successful brain targeting offering direct nose-to-brain drug delivery.

Design as strategy for evaluation of the mechanical properties of binary mixtures composed of poly(methyl vinyl ether-alt-maleic anhydride) and Pluronic F127 for biomedical applications

The synergism between thermoresponsive and bioadhesive polymers can lead to the optimization of materials with enhanced mechanical and bioadhesive properties. Quality by Design can assure the understanding and control of formulation variables. In this approach, Design of Experiment has been widely utilized as an important strategy. Poly(methyl vinyl ether-alt-maleic anhydride) (PVMMA) is a bioadhesive polymer and Pluronic F127 (PF127) shows thermoresponsiveness. The association of these two polymers has been poorly investigated. The aim of this work was to study the mechanical, bioadhesive and rheological properties of polymer mixtures composed of PVMMA and PF127, in order to select the best conditions and formulations for biomedical applications. Textural properties (hardness, compressibility, adhesiveness, cohesiveness and elasticity), softness index, bioadhesion and rheological characteristics (flow and viscoelasticity) showed that 17.5-20% (w/w) PF127-polymer mixtures displayed improved values of the parameters. However, the rheological interaction parameter showed low synergism, due to the polymers' characteristics and system organization. The formulations displayed gelation temperatures suitable for administration, with improved bioadhesive properties mainly at 34 °C and suggests the formulations can be used for biomedical applications. DoE constituted an important tool to investigate these systems showing the main effects that significantly influence the binary mixtures.

Potential Hemostatic and Wound Healing Effects of Thermoresponsive Wound Dressing Gel Loaded with Lignosus rhinocerotis and Punica granatum Extracts

Biologically active compounds in Lignosus rhinocerotis and Punica granatum are found to facilitate wound healing and exhibit hemostatic activity, making them a good combination as bioactives for wound dressings. This study, therefore, aimed to evaluate the potential of thermoresponsive gels loaded with L. rhinocerotis (HLRE) and P. granatum (PPE) extracts as dressings for wound treatment. The gels were prepared using Pluronic PF127 polymer and mixed with PEG 400 and/or starch prior to incorporation with both extracts (0.06 to 1 mg/mL). The gelation temperature (Tgel) at the skin temperature was achieved when Pluronic PF127 was mixed with 22% w/v PEG 400 and reduced to 25.7 ± 0.3-26.7 ± 1.2 °C after adding HLRE and PPE. The gels exhibited satisfactory hardness (2.02 ± 0.19-6.45 ± 0.53 N), cohesiveness (0.9 ± 0.07-2.28 ± 0.4 mJ), adhesiveness (5.07 ± 2.41-19.6 ± 1.1 mJ), and viscosity (0.15 ± 0.04-0.95 ± 0.03 Pa.s), suitable for wound dressings. The optimized gels displayed high thrombin activity and cell migration rate (wound closure of 74% ± 12-89% ± 2 within 24 h), demonstrating hemostatic and healing effects. The thermoresponsive gels demonstrated advantages to be used as dressings for treating acute and open wounds.

Photo-Phytotherapeutic Gel Composed of Copaifera reticulata, Chlorophylls, and k-Carrageenan: A New Perspective for Topical Healing

Chronic wound healing represents an impactful financial burden on healthcare systems. In this context, the use of natural products as an alternative therapy reduces costs and maintains effectiveness. Phytotherapeutic gels applied in photodynamic therapy (PDT) have been developed to act as topical healing medicines and antibiotics. The bioactive system is composed of Spirulina sp. (source of chlorophylls) and Copaifera reticulata oil microdroplets, both incorporated into a polymeric blend constituted by kappa-carrageenan (k-car) and F127 copolymer, constituting a system in which all components are bioactive agents. The flow behavior and viscoelasticity of the formulations were investigated. The photodynamic activity was accessed from studies of the inactivation of Staphylococcus aureus bacteria, the main pathogen of hospital relevance. Furthermore, in vivo studies were conducted using eighteen rabbits with dermatitis (grade III and IV) in both paws. The gels showed significant antibiotic potential in vitro, eliminating up to 100% of S. aureus colonies in the presence or absence of light. The k-car reduced 41% of the viable cells; however, its benefits were enhanced by adding chlorophyll and copaiba oil. The animals treated with the phytotherapeutic medicine showed a reduction in lesion size, with healing and re-epithelialization verified in the histological analyses. The animals submitted to PDT displayed noticeable improvement, indicating this therapy's viability for ulcerative and infected wounds. This behavior was not observed in the iodine control treatment, which worsened the animals' condition. Therefore, gel formulations were a viable alternative for future pharmaceutical applications, aiming at topical healing.

Curcumin-Loaded Mesoporous Silica Nanoparticles Dispersed in Thermo-Responsive Hydrogel as Potential Alzheimer Disease Therapy

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by cognitive and behavioral impairment. Curcumin-loaded mesoporous silica nanoparticles (MSN-CCM) can overcome the drawbacks related to the free curcumin (CCM) clinical application, such as water insolubility and low bioavailability, besides acting over the main causes associated to AD. A thermo-responsive hydrogel is an interesting approach for facilitating the administration of the nanosystem via a nasal route, as well as for overcoming mucociliary clearance mechanisms. In light of this, MSN-CCM were dispersed in the hydrogel and evaluated through in vitro and in vivo assays. The MSNs and MSN-CCM were successfully characterized by physicochemical analysis and a high value of the CCM encapsulation efficiency (EE%, 87.70 ± 0.05) was achieved. The designed thermo-responsive hydrogel (HG) was characterized by rheology, texture profile analysis, and ex vivo mucoadhesion, showing excellent mechanical and mucoadhesive properties. Ex vivo permeation studies of MSN-CCM and HG@MSN-CCM showed high permeation values (12.46 ± 1.08 and 28.40 ± 1.88 μg cm⁻² of CCM, respectively) in porcine nasal mucosa. In vivo studies performed in a streptozotocin-induced AD model confirmed that HG@MSN-CCM reverted the cognitive deficit in mice, acting as a potential formulation in the treatment of AD.

Increasing the Hydrophobic Component of Poloxamers and the Inclusion of Salt Extend the Release of Bupivacaine from Injectable In Situ Gels, While Common Polymer Additives Have Little Effect

Various strategies have been applied to reduce the initial burst of drug release and sustain release from poloxamer-based thermoresponsive gels. This work focussed on investigating different formulation approaches to minimise the initial burst of release and sustain the release of the small hydrophilic drug bupivacaine hydrochloride from poloxamer-based thermoresponsive gels. Various in situ gel formulations were prepared by varying the polypropylene oxide (PPO)/polyethylene oxide (PEO) ratio and by adding additives previously described in the literature. It was observed that increasing the PPO/PEO ratio from 0.28 to 0.30 reduced the initial burst release from 17.3% ± 1.8 to 9.1% ± 1.2 during the first six hours and extended the release profile from 10 to 14 days. Notably, the inclusion of sodium chloride (NaCl 0.4% w/w) further reduced the initial burst release to 1.8% ± 1.1 over the first 6 h. Meanwhile, physical blending with additive polymers had a negligible effect on the burst release and overall release profile. The findings suggest that extended release of bupivacaine hydrochloride, with reduced initial burst release, can be achieved simply by increasing the PPO/PEO ratio and the inclusion of NaCl.

Thermosensitive gel based on cellulose derivative for topical delivery of propolis in acne treatment

Thermosensitive bioadhesive formulations can display increased retention time, skin permeation, and improve the topical therapy of many drugs. Acne is an inflammatory process triggered by several factors like the proliferation of the bacteria Propionibacterium acnes. Aiming a new alternative treatment with a natural source, propolis displays great potential due to its antibiotic, anti-inflammatory and healing properties. This study describes the development of bioadhesive thermoresponsive platform with cellulose derivatives and poloxamer 407 for propolis skin delivery. Propolis ethanolic extract (PES) was added to the formulations with sodium carboxymethylcellulose (CMC) or hydroxypropyl methylcellulose (HPMC) and poloxamer 407 (Polox). The formulations were characterized as rheology, bioadhesion and mechanical analysis. The selected formulations were investigated as in vitro propolis release, cytotoxicity, ex vivo skin permeation by Fourier Transform Infrared Photoacoustic Spectroscopy, and the activity against P. acnes. Formulations showed suitable sol-gel transition temperature, shear-thinning behavior and texture profile. CMC presence decreased cohesiveness and adhesiveness of formulations. Polox/HPMC/PES system displayed less cytotoxicity, modified propolis release governed by anomalous transport, skin permeation and activity against P. acnes. These results indicate important advantages in the topical treatment of acne and suggest a potential formulation for clinical evaluation.

Preparation, in vitro and in vivo Evaluation of Thermosensitive in situ Gel Loaded with Ibuprofen-Solid Lipid Nanoparticles for Rectal Delivery

Background

Ibuprofen (IBU), a nonsteroidal anti-inflammatory drug, shows poor gastrointestinal absorption due to its low solubility, which limits its clinical application.

Objective

In the present study, we aimed to develop thermosensitive gel-mediated ibuprofen-solid lipid nanoparticles (IBU-SLN-ISG) to improve the dissolution and bioavailability of IBU after rectal delivery.

Methods

IBU-loaded SLNs (IBU-SLNs) were developed and optimized applying Box-Behnken design. The optimized IBU-SLNs were characterized by physicochemical parameters and morphology. Then, the optimized IBU-SLNs was incorporated into the gel and characterized for gel properties and rheology and investigated its release in vitro, pharmacokinetics in vivo, rectal irritation and rectal retention time.

Results

The optimized SLNs had an EE of 90.74 ± 1.40%, DL of 11.36 ± 1.20%, MPS of 166.77 ± 2.26 nm, PDI of 0.27 ± 0.08, and ZP of −21.00 ± 0.59 mV. The FTIR spectra confirmed successful encapsulation of the drug inside the nanoparticle as only peaks responsible for the lipid could be identified. This corroborated well with XRD spectra, which showed a completely amorphous state of the IBU-SLNs as compared to the crystalline nature of the pure drug. The gelation temperature of the prepared IBU-SLN-ISG was 33.30 ± 0.78°C, the gelation time was 14.67 ± 2.52 s, the gel strength was 54.00 ± 1.41 s, and the mucoadhesion was (11.54±0.37) × 10²dyne/cm². The in vitro results of IBU-SLNs and IBU-SLN-ISG showed a biphasic release pattern with initial burst release followed by sustained release. More importantly, IBU-SLN-ISG produced much better absorption of IBU and improved bioavailability in rats. In addition, IBU-SLN-ISG caused no irritation or damage to rectal tissues, and could be retained in the rectum for a long time.

Conclusion

Thermosensitive in situ gel loaded with IBU-solid lipid nanoparticles might be further developed as a more convenient and effective rectal dosage form.

Formulation and Evaluation of Hybrid Niosomal In Situ Gel for Intravesical Co-Delivery of Curcumin and Gentamicin Sulfate

The current study describes the elaboration of a hybrid drug delivery platform for an intravesical application based on curcumin/gentamicin sulfate simultaneously loaded niosomes incorporated into thermosensitive in situ gels. Series of niosomes were elaborated via the thin film hydration method, evaluating the impact of non-ionic surfactants’, cholesterol’s, and curcumin’s concentration. The formulation composed of equimolar ratio of Span 60, Tween 60, and 30 mol% cholesterol was selected as the optimal composition, due to the high entrapment efficiency values obtained for both drugs, and appropriate physicochemical parameters (morphology, size, PDI, and zeta potential), therefore, was further incorporated into Poloxamers (407/188) and Poloxamers and chitosan based in situ gels. The developed hybrid systems were characterized with sol to gel transition in the physiological range, suitable rheological and gelling characteristics. In addition, the formed gel structure at physiological temperatures determines the retarded dissolution of both drugs (vs. niosomal suspension) and sustained release profile. The conducted microbial studies of selected niosomal in situ gels revealed the occurrence of a synergetic effect of the two compounds when simultaneously loaded. The findings indicate that the elaborated thermosensitive niosomal in situ gels can be considered as a feasible platform for intravesical drug delivery.

Optimization of the Micellar-Based In Situ Gelling Systems Posaconazole with Quality by Design (QbD) Approach and Characterization by In Vitro Studies

Background: Fungal ocular infections can cause serious consequences, despite their low incidence. It has been reported that Posaconazole (PSC) is used in the treatment of fungal infections in different ocular tissues by diluting the oral suspension, and successful results were obtained despite low ocular permeation. Therefore, we optimized PSC-loaded ocular micelles and demonstrated that the permeation/penetration of PSC in ocular tissues was enhanced. Methods: The micellar-based in situ gels based on the QbD approach to increase the ocular bioavailability of PSC were developed. Different ratios of Poloxamer 407 and Poloxamer 188 were chosen as CMAs. Tsol/gel, gelling capacity and rheological behavior were chosen as CQA parameters. The data were evaluated by Minitab 18, and the formulations were optimized with the QbD approach. The in vitro release study, ocular toxicity, and anti-fungal activity of the optimized formulation were performed. Results: Optimized in situ gel shows viscoelastic property and becomes gel form at physiological temperatures even when diluted with the tear film. In addition, it has been shown that the formulation had high anti-fungal activity and did not have any ocular toxicity. Conclusions: In our previous studies, PSC-loaded ocular micelles were developed and optimized for the first time in the literature. With this study, the in situ gels of PSC for ocular application were developed and optimized for the first time. The optimized micellar-based in situ gel is a promising drug delivery system that may increase the ocular permeation and bioavailability of PSC.

Photoprotection and skin irritation effect of hydrogels containing hydroalcoholic extract of red propolis: A natural pathway against skin cancer

The use of natural products in sunscreen formulations as a prophylactic measure against skin cancer is receiving special attention attributed to the photoprotective and antioxidant properties of their chemical components. In this work, we describe the development of topical hydrogel formulations containing hydroalcoholic extract of red propolis (HERP), and the evaluation of the dermal sensitizing effect of the developed products. Sunscreen formulations composed of HERP in different concentrations (1.5, 2.5 or 3.5% w/w) alone or in combination with a chemical (octyl methoxycinnamate) and/or physical (titanium dioxide) filters were developed using poloxamer 407 as gel basis. The preliminary and accelerated stability tests, texture analysis and spreadability tests were performed. All formulations revealed to be stable in preliminary stability assessment. The formulations containing HERP 1.5 and 2.5% alone or associated with the filters showed intense modifications during accelerated stability test, which were confirmed by rheological analyses. The incorporation of HERP and filters in the poloxamer hydrogel decreased the toughness of product (p < 0.05) and the formulation containing HERP alone presented the lowest adhesivity (p < 0.001). The incorporation of HERP in the hydrogel decreased the poloxamer transition temperature, showing different rheological behavior with the increase of HERP concentration. The developed formulations were stable, exhibited non-Newtonian and pseudoplastic behavior, showing in vivo skin compatibility and no skin irritancy.

Injectable In Situ Gelling System for Sustained Nicotine Delivery as a Replacement Therapy for Smoking Cessation

Nicotine replacement therapy (NRT) is widely used to limit the withdrawal symptoms associated with cigarette smoking cessation. However, the available NRT formulations are limited by their short release profiles, requiring frequent administrations along with local side effects. Thus, the objective of this study is to develop an NRT formulation that offers prolonged, sustained nicotine release. Thermoresponsive in situ gelling systems containing nicotine were prepared using poloxamer 407 (P407) and poloxamer 188 (P188). The system was optimized using a three-factor, two-level full factorial design (23). A formulation composed of P407 (20% w/w), P188 (5% w/w), and loaded with nicotine (0.5% w/w) exhibited sol-to-gel transition at a suitable temperature close to physiological temperature (30 °C). The rheological analysis demonstrated a Newtonian-like flow at room temperature, suggesting ease of administration via injection, and semisolid gel status at physiological temperature. The optimized formulation successfully sustained nicotine in vitro release over 5 days following single administration. The findings suggest that poloxamer based in situ gelling systems are promising platforms to sustain the release of nicotine.

Clozapine-Encapsulated Binary Mixed Micelles in Thermosensitive Sol-Gels for Intranasal Administration

(1) Background: Clozapine is the most effective antipsychotic. It is, however, associated with many adverse drug reactions. Nose-to-brain (N2B) delivery offers a promising approach. This study aims to develop clozapine-encapsulated thermosensitive sol-gels for N2B delivery. (2) Methods: Poloxamer 407 and hydroxypropyl methylcellulose were mixed and hydrated with water. Glycerin and carbopol solutions were added to the mixture and stirred overnight at 2-8 °C. Clozapine 0.1% w/w was stirred with polysorbate 20 (PS20) or polysorbate 80 (PS80) at RT (25 °C) before being added to the polymer solution. The final formulation was made to 10 g with water, stirred overnight at 2-8 °C and then adjusted to pH 5.5. (3) Results: Formulations F3 (3% PS20) and F4 (3% PS80) were selected for further evaluation, as their gelation temperatures were near 28 °C. The hydrodynamic particle diameter of clozapine was 18.7 ± 0.2 nm in F3 and 20.0 ± 0.4 nm in F4. The results show a crystallinity change in clozapine to amorphous. Drug release studies showed a 59.1 ± 3.0% (F3) and 53.1 ± 2.7% (F4) clozapine release after 72 h. Clozapine permeated after 8 h was 20.8 ± 3.0% (F3) and 17.8 ± 3.1% (F4). The drug deposition was higher with F4 (144.8 ± 1.4 µg/g) than F3 (110.7 ± 2.7 µg/g). Both sol-gels showed no phase separation after 3 months. (4) Conclusions: Binary PS80-P407 mixed micelles were more thermodynamically stable and rigid due to the higher synergism of both surfactants. However, binary mixed PS20-P407 micelles showed better drug permeation across the nasal mucosa tissue and may be a preferable carrier system for the intranasal administration of clozapine.

Development of mucoadhesive thiomeric chitosan nanoparticles for the targeted ocular delivery of vancomycin against Staphylococcus aureus resistant strains

This study aims to formulate mucoadhesive vancomycin loaded thiolated chitosan (TCS) nanoparticles. These nanoparticles are mucoadhesive and enhance the retention of the drug at the ocular site. For this purpose, TCS loaded vancomycin nanoparticles were prepared by the ion-gelation method and were characterized for their size, shape, polydispersity index, mucoadhesion, cellular uptake and anti-inflammatory activity. The average size of the synthesized nanoparticles was found to be 288 nm with positive zeta potential. Moreover, 85% vancomycin was successfully encapsulated in TCS nanoparticles by using this method. A 2-fold increase in mucoadhesion was found as compared to non-thiolated vancomycin formulation (p < 0.05). Zone of inhibition of vancomycin loaded TCS was also significantly improved compared to non-thiolated chitosan nanoparticles and vancomycin alone. In-vivo anti-inflammatory evaluation via histopathology resulted in ocular healing. Based on the results, it is inferred that TCS nanoparticles are a promising drug delivery carrier system for ocular delivery of vancomycin.

Synthesis, classification and properties of hydrogels: their applications in drug delivery and agriculture

Absorbent polymers or hydrogel polymer materials have an enhanced water retention capacity and are widely used in agriculture and medicine. The controlled release of bioactive molecules (especially drug proteins) by hydrogels and the encapsulation of living cells are some of the active areas of drug discovery research. Hydrogel-based delivery systems may result in a therapeutically advantageous outcome for drug delivery. They can provide various sequential therapeutic agents including macromolecular drugs, small molecule drugs, and cells to control the release of molecules. Due to their controllable degradability, ability to protect unstable drugs from degradation and flexible physical properties, hydrogels can be used as a platform in which various chemical and physical interactions with encapsulated drugs for controlled release in the system can be studied. Practically, hydrogels that possess biodegradable properties have aroused greater interest in drug delivery systems. The original three-dimensional structure gets broken down into non-toxic substances, thus confirming the excellent biocompatibility of the gel. Chemical crosslinking is a resource-rich method for forming hydrogels with excellent mechanical strength. But in some cases the crosslinker used in the synthesis of the hydrogels may cause some toxicity. However, the physically cross-linked hydrogel preparative method is an alternative solution to overcome the toxicity of cross-linkers. Hydrogels that are responsive to stimuli formed from various natural and synthetic polymers can show significant changes in their properties under external stimuli such as temperature, pH, light, ion changes, and redox potential. Stimulus-responsive hydrogels have a wider range of applications in biomedicine including drug delivery, gene delivery and tissue regeneration. Stimulus-responsive hydrogels loaded with multiple drugs show controlled and sustained drug release and can act as drug carriers. By integrating stimulus-responsive hydrogels, such as those with improved thermal responsiveness, pH responsiveness and dual responsiveness, into textile materials, advanced functions can be imparted to the textile materials, thereby improving the moisture and water retention performance, environmental responsiveness, aesthetic appeal, display and comfort of textiles. This review explores the stimuli-responsive hydrogels in drug delivery systems and examines super adsorbent hydrogels and their application in the field of agriculture.

Determination of Microstructural Impact on the Release of Drug from Hydroxypropyl Cellulose Gel by Validated In Vitro Release Test Method

Microstructure of a semisolid system is greatly influenced by the formulation composition and the processing parameters. Different polymers exhibit different three-dimensional structure and these have a great impact on the drug release properties. The current research focuses on studying the impact of hydroxypropyl cellulose gel microstructure on the release properties of chlorhexidine gluconate (CHX G). The two main investigating methods of microstructure were used namely, rheology and texture analysis to determine the differences in the formulations studied. The CHX G drug release study was performed using a developed and validated in vitro release test method, which is reproducible, discriminative, and robust to detect the formulation differences. The drug release results showed that there was appreciable difference in the release rates of the different formulations. The rheology and texture analysis data correlated well with the difference in the release rates. The formulations differences were further confirmed by a statistical approach using analysis of variance.

Mucoadhesive, Thermoreversible Hydrogel, Containing Tetracaine-Loaded Nanostructured Lipid Carriers for Topical, Intranasal Needle-Free Anesthesia

Recent advances have been reported for needle-free local anesthesia in maxillary teeth by administering a nasal spray of tetracaine (TTC) and oxymetazoline, without causing pain, fear, and stress. This work aimed to assess whether a TTC-loaded hybrid system could reduce cytotoxicity, promote sustained permeation, and increase the anesthetic efficacy of TTC for safe, effective, painless, and prolonged analgesia of the maxillary teeth in dental procedures. The hybrid system based on TTC (4%) encapsulated in nanostructured lipid carriers (NLC) and incorporated into a thermoreversible hydrogel of poloxamer 407 (TTCNLC-HG4%) displayed desirable rheological, mechanical, and mucoadhesive properties for topical application in the nasal cavity. Compared to control formulations, the use of TTCNLC-HG4% slowed in vitro permeation of the anesthetic across the nasal mucosa, maintained cytotoxicity against neuroblastoma cells, and provided a three-fold increase in analgesia duration, as observed using the tail-flick test in mice. The results obtained here open up perspectives for future clinical evaluation of the thermoreversible hybrid hydrogel, which contains TTC-loaded NLC, with the aim of creating an effective, topical, intranasal, needle-free anesthesia for use in dentistry.

Development and Evaluation of Thermosensitive Hydrogels with Binary Mixture of Scutellariae baicalensis radix Extract and Chitosan for Periodontal Diseases Treatment

Scutellaria baicalensis root displays anti-inflammatory and antibacterial properties due to the presence of flavonoids, particularly baicalin, baicalein, and wogonin. Our work aimed at developing thermosensitive hydrogels containing a binary mixture of S. baicalensis radix lyophilized extract and chitosan as a novel approach for periodontal diseases treatment. Two types of chitosan were employed in preliminary studies on binary mixtures with S. baicalensis radix lyophilized extract standardized for baicalin, baicalein, and wogonin. Thermosensitive hydrogels were prepared of poloxamer 407, alginate sodium, and cellulose derivatives and evaluated in terms of rheological and mucoadhesive behavior. The presence of chitosan altered the release profile of active compounds but did not affect their in vitro permeation behavior in PAMPA assay. The synergistic effects of S. baicalensis radix lyophilized extract and chitosan toward ferrous ion-chelating activity, inhibition of hyaluronidase, and pathogen growth were observed. The thermosensitive gelling system showed shear-thinning properties, gelation temperature between 25 and 27 °C, and favorable mucoadhesiveness in contact with porcine buccal mucosa, which was enhanced in the presence of binary mixture of S. baicalensis radix extract and chitosan. The release tests showed that baicalin and baicalein were liberated in a prolonged manner with a fast onset from hydrogel formulations.

Dual Action Gels Containing DsiRNA Loaded Gold Nanoparticles: Augmenting Diabetic Wound Healing by Promoting Angiogenesis and Inhibiting Infection

Hyperglycemia induces the prostaglandin transporter (PGT) gene overexpression, leading to poor vascularization and wound healing. Dicer substrate small interfering RNA (DsiRNA) and gold nanoparticles (AuNPs) co-loaded into PF127 gel was developed to overcome the disturbance and infections. The AuNPs were biosynthesized using cold and hot water extracts of Lignosus rhinocerotis (abbreviated CLRE and HLRE, respectively). The wound healing efficacy of a PF127 gel containing DsiRNA-AuNPs-CLRE and -HLRE (assigned as F2 and F3, respectively) was evaluated in a diabetes-induced Wistar rat model. The F2 (DC) and F3 (DH) treated groups revealed a faster wound closure (92.67 ± 3.4% and 85.1 ± 7.3%, respectively) than the positive control (commercial gel, DTI)(74.9 ± 13.3%). DH and DC groups presented an increased blood vessel density, along with decreased inflammatory cells. In comparison to positive control, higher prostaglandin E₂ (PGE₂) (495 ±79 and 50 ±121 pg/mL, for DC and DH group, respectively), vascular endothelial growth factor (VEGF) (49 ±15 and 38 ±3 pg/mL, for DC and DH group, respectively) and VEGF-A levels were detected in both groups (DC and DH), indicating the effectiveness of DsiRNA in enhancing PGE₂ production and vascularization. On evaluating microbiomes adhered to the wound areas, Gram-positive bacteria Staphylococcus and Corynebacterium, as well as Gram-negative Pseudomonas, Rodentibacter, and Acinetobacter, were found to be sensitive to the gel. Collectively, the gel was confirmed as a promising dressing for diabetic wound therapy, warranting further studies for clinical use.