Evaluation and Optimization of Prolonged Release Mucoadhesive Tablets of Dexamethasone for Wound Healing: In Vitro–In Vivo Profiling in Healthy Volunteers

Thiolated hemicellulose containing mucoadhesive and permeation-enhancing ocular films of levodopa for potential treatment of myopia

The ocular bioavailability of a drug is inadequate due to physiological constraints. In this study, an ocular film of Levodopa (LD) using thiolated hemicellulose (THC) with improved mucoadhesion and permeation was made. Linseed hemicellulose (LHC) was extracted, and its esterification was done with thioglycolic acid (TGA), L cysteine (LC), and thiourea (TU). Maximum thiolation of LHC was confirmed by Ellman's test, Fourier-transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Primary eye irritation tests and histopathological studies of different ocular tissues like cornea, conjunctiva, and sclera conducted on rabbit eyes exhibited nontoxic and non-irritant behavior of LHC and optimized derivative of LHC with TGA (THT-960) which was further used for the preparation of LD-containing ocular films i.e., LD-THC, LD-THT960, and LD-THT960-THC, respectively. Ascorbic acid was added to the ocular film to prevent oxidation of LD. Ex-vivo permeation studies from bovine cornea showed a 1.8fold increase in corneal permeation of LD while ocular irritancy by hen egg chorioallantoic membrane (HET-CAM) test and histopathological analysis confirmed nonirritant and nontoxic nature of THT-960. Conclusively, LD-THT960 due to improved mucoadhesion and corneal permeation of LD can be used effectively for the potential treatment of myopia.

A preliminary study on ultrasound techniques applied to evaluate the curative effect of botulinum toxin type a in hypertrophic scars

Objective

To validate the feasibility of ultrasound in assessing the curative effect of botulinum toxin type A (BTXA) in treating hypertrophic scar (HS).

Methods

Eight healthy New Zealand long-eared rabbits were utilized in the study. Four wounds, each measuring 1.0 cm in diameter, were created on both ears of each rabbit. Immediately after surgery, each of these wounds received an injection containing a distinct concentration of BTXA. On postoperative week 6, scar thickness, vascularity, and hardness were assessed based on high frequency ultrasound (HFUS), superb microvascular imaging (SMI), shear wave elastography (SWE), Masson staining, and immunohistochemical staining for CD31.

Results

All wounds healed well, and HSs formed after 6 weeks post-surgery. Scar thickness based on HFUS presented a significant decrease with increasing BTXA concentration (p < 0.05), aligning with the gross morphology. Simultaneously, scar stiffness, evaluated using SWE, showed a significant decrease in accordance with the variation of the collagen volume fraction, which refers to the ratio of the collagen positive area to the total area (p < 0.05). Although the vascularity index obtained by SMI did not exhibit a statistically significant change across different BTXA concentrations, this technique effectively illustrated the microvascular perfusion in HS. Immunohistochemical staining for CD31 revealed that BTXA inhibited angiogenesis.

Conclusion

HFUS and SWE displayed excellent performance in evaluating HS thickness and stiffness. SMI showed a good performance in reflecting microvascular signals in HS. These ultrasound techniques have great potential in assessing the therapeutic effect of BTXA in HS.

On the mucoadhesive properties of synthetic and natural polyampholytes

HYPOTHESIS

The mucoadhesive characteristics of amphoteric polymers (also known as polyampholytes) can vary and are influenced by factors such as the solution's pH and its relative position against their isoelectric point (pHIEP). Whilst the literature contains numerous reports on mucoadhesive properties of either cationic or anionic polymers, very little is known about these characteristics for polyampholytes EXPERIMENTS: Here, two amphoteric polymers were synthesized by reaction of linear polyethylene imine (l-PEI) with succinic or phthalic anhydride and their mucoadhesive properties were compared to bovine serum albumin (BSA), selected as a natural polyampholyte. Interactions between these polymers and porcine gastric mucin were studied using turbidimetric titration and isothermal titration calorimetry across a wide range of pHs. Model tablets were designed, coated with these polymers and tested to evaluate their adhesion to porcine gastric mucosa at different pHs. Moreover, a retention study using fluorescein isothiocyanate (FITC)-labelled polyampholytes deposited onto mucosal surfaces was also conducted FINDINGS: All these studies indicated the importance of solution pH and its relative position against pHIEP in the mucoadhesive properties of polyampholytes. Both synthetic and natural polyampholytes exhibited strong interactions with mucin and good mucoadhesive properties at pH < pHIEP.

Release Kinetics of Dexamethasone Phosphate from Porous Chitosan: Comparison of Aerogels and Cryogels

Porous chitosan materials as potential wound dressings were prepared via dissolution of chitosan, nonsolvent-induced phase separation in NaOH-water, formation of a hydrogel, and either freeze-drying or supercritical CO2 drying, leading to "cryogels" and "aerogels", respectively. The hydrophilic drug dexamethasone sodium phosphate was loaded by impregnation of chitosan hydrogel, and the release from cryogel or aerogel was monitored at two pH values relevant for wound healing. The goal was to compare the drug-loading efficiency and release behavior from aerogels and cryogels as a function of the drying method, the materials' physicochemical properties (density, morphology), and the pH of the release medium. Cryogels exhibited a higher loading efficiency and a faster release in comparison with aerogels. A higher sample density and lower pH value of the release medium resulted in a more sustained release in the case of aerogels. In contrast, for cryogels, the density and pH of the release medium did not noticeably influence release kinetics. The Korsmeyer-Peppas model showed the best fit to describe the release from the porous chitosan materials into the different media.

Development and Characterization of Gel-Based Buccoadhesive Bilayer Formulation of Nifedipine

A promising controlled drug delivery system has been developed based on polymeric buccoadhesive bilayered formulation that uses a drug-free backing layer and a polymeric hydrophilic gel buccoadhesive core layer containing nifedipine. The DSC thermogravimetric analysis confirms the drug's entrapment in the gel layer and reveals no evidence of a potential interaction. Various ratios of bioadhesive polymers, including HPMC K100, PVP K30, SCMC, and CP 934, were combined with EC as an impermeable backing layer to ensure unidirectional drug release towards the buccal mucosa. The polymeric compositions of hydrophilic gel-natured HPMC, SCMC, and CP formed a matrix layer by surrounding the core nifedipine during compression. Preformulation studies were performed for all of the ingredients in order to evaluate their physical and flow characteristics. Ex vivo buccoadhesive strength, surface pH, swelling index, in vitro and in vivo drug release, and ex vivo permeation investigations were performed to evaluate the produced gel-based system. Rapid temperature variations had no appreciable impact on the substance's physical properties, pharmacological content, or buccoadhesive strength during stability testing using actual human saliva. It was clear from a histological examination of the ex vivo mucosa that the developed system did not cause any irritation or inflammation at the site of administration. The formulation NT5 was the best one, with a correlation coefficient of 0.9966. The in vitro and in vivo drug release profiles were well correlated, and they mimic the in vitro drug release pattern via the biological membrane. Thus, the developed gel-based formulation was found to be novel, stable, and useful for the targeted delivery of nifedipine.

Mechanochemical Properties of Mucoadhesive Tablets Based on PVP/HPβCD Electrospun Nanofibers as Local Delivery of Polygoni cuspidati Extract for Treating Oral Infections

This study investigated the ability of PVP/HPβCD-based electrospun nanofibers to enhance the dissolution rate of poorly soluble polydatin and resveratrol, the main active components of Polygoni cuspidati extract. To make a solid unit dosage form that would be easier to administer, extract-loaded nanofibers were ground. SEM examination was used to analyze the nanostructure of the fibers, and the results of the cross-section of the tablets showed that they had maintained their fibrous structure. The release of the active compounds (polydatin and resveratrol) in the mucoadhesive tablets was complete and prolonged in time. Additionally, the possibility of staying on the mucosa for a prolonged time has also been proven for both tablets from PVP/HPβCD-based nanofibers and powder. The appropriate physicochemical properties of the tablets, along with the proven antioxidant, anti-inflammatory, and antibacterial properties of P. cuspidati extract, highlight the particular benefits of the mucoadhesive formulation for use as a drug delivery system for periodontal diseases.

Evaluating Novel Agarose-Based Buccal Gels Scaffold: Mucoadhesive and Pharmacokinetic Profiling in Healthy Volunteers

Agarose (AG) forms hydrocolloid in hot water and possesses a noteworthy gel strength. However, no reasonable scientific work on investigating the mucoadhesive character of AG has been reported. Therefore, the current study was designed to develop AG and carbopol (CP) based buccal gel scaffold for simultaneous release of benzocaine (BZN) and tibezonium iodide (TIB). Gels’ scaffold formulations (F1−F12) were prepared with varied concentrations (0.5−1.25% w/v) of AG and CP alone or their blends (AG-CP) using homogenization technique. The prepared formulations were characterized for solid-state, physicochemical, in vitro, ex vivo, and in vivo mucoadhesive studies in healthy volunteers. The results showed that mucoadhesive property of AG was concentration dependent but improved by incorporating CP in the scaffolds. The ex vivo mucoadhesive time reached >36 h when AG was used alone or blended with CP at 1% w/v concentration or above. The optimized formulation (F10) depicted >98% drugs release within 8 h and was also storage stable up to six months. The salivary concentration of BZN and TIB from formulation F10 yielded a Cmax value of 9.97 and 8.69 µg/mL at 2 and 6 h (tmax), respectively. In addition, the FTIR, PXRD, and DSC results confirmed the presence of no unwanted interaction among the ingredients. Importantly, the mucoadhesive study performed on healthy volunteers did not provoke any signs of inflammation, pain, or swelling. Clearly, it was found from the results that AG-CP scaffold provided better mucoadhesive properties in comparison to pure AG or CP. Conclusively, the developed AG based mucoadhesive drug delivery system could be considered a potential alternative for delivering drugs through the mucoadhesive buccal route.

Exorbitant Drug Loading of Metformin and Sitagliptin in Mucoadhesive Buccal Tablet: In Vitro and In Vivo Characterization in Healthy Volunteers

The aim of the proposed study is to develop a mucoadhesive buccal delivery system for the sustained delivery of metformin (MET) and sitagliptin (SIT) against diabetes mellitus (DM) with improved bioavailability. Polymeric blend of Carbopol® 940 (CP), agarose (AG) or polyvinylpyrrolidone K30 (PVP) as mucoadhesive agents in formulations (R1-R15) were compressed via the direct compression technique. Tablets were characterized for solid state studies, physicochemical and in vivo mucoadhesion studies in healthy volunteers. Outcomes did not reveal any unusual peak or interaction between the drugs and polymers in the physical mixture through Fourier Transform Infrared Spectroscopy (FTIR) and DSC analysis. The mucoadhesive blend of CP and PVP was superior compared to other blends. The formulation R4 revealed exorbitant loading of drugs with complete drug release for 6 h with ex vivo mucoadhesive strength and time of 26.99 g and 8.1 h, respectively. It was further scrutinized to evaluate it as an optimized formulation where it was found to be stable for up to 6 months. The formulation R4 depicted Korsmeyer-Peppas model and first-order mode of release correspondingly for SIT and MET. Moreover, it showed hemocompatibility, biocompatibility and stability with non-significant changes in the dissolution profile. Overall, the CP blend with PVP was found appropriate to yield the desired release coupled with the optimized mucoadhesive properties of the buccal tablets, ensuring sufficient pharmaceutical stability.