Mucoadhesive Electrospun Patch Delivery of Lidocaine to the Oral Mucosa and Investigation of Spatial Distribution in a Tissue Using MALDI-Mass Spectrometry Imaging

Inhibition of compound action potentials in the frog sciatic nerve by inchinkoto, a traditional Japanese medicine used for oral mucositis

OBJECTIVE

This study aimed to determine the effects of traditional Japanese (Kampo) medicines used to treat oral mucositis on nerve conduction.

METHODS

The effects of Kampo medicines, crude drugs, and chemical compounds on compound action potentials (CAPs) were analyzed using extracellular recordings in frog sciatic nerves.

RESULTS

Among the Kampo medicines, inchinkoto demonstrated the most significant reduction in CAP amplitude, with a half-maximal inhibitory concentration (IC50) of 5.4 mg/mL. Hangeshashinto, shosaikoto, hochuekkito, and juzentaihoto also showed a significant reduction. Regarding inchinkoto, Artemisiae Capillari Spica (artemisia) was the most effective crude drug, with an IC50 of 4.2 mg/mL for CAP amplitude reduction, whereas Gardeniae Fructus (gardenia) exerted no significant effect. However, the combined use of artemisia and gardenia reduced the CAP amplitude more effectively than artemisia alone, indicating a synergistic interaction. The chemical ingredient eugenol from artemisia administered at 1 and 3 mmol/L reduced CAP amplitude, whereas other chemical ingredients administered at 0.1 and 1 mmol/L had no significant effects.

CONCLUSIONS

Inchinkoto exhibited the most effective reduction in CAP amplitude in the sciatic nerve of frogs, primarily through the action of artemisia, with potential synergistic interaction between artemisia and gardenia.

Eutectic phase transition during tablet manufacture: effect of melting point of eutectic forming drug

The aim was to investigate eutectic transition during tableting and storage. Mixtures of lidocaine and series of NSAIDs with increasing melting point were used as model systems to guide formulators to scaleup eutectic forming materials gaining enhanced dissolution while avoiding deleterious physical changes. Physical mixtures of NSAIDs with lidocaine were prepared at eutectic forming ratio. These were directly compressed, dry co-ground before compression, or compressed after wet granulation. Dissolution of tablets was compared to corresponding dry co-ground mixture. Thermograms of direct compressed tablet were compared to co-ground mixture and pure compound. Stability of direct compressed tablets was assessed. Tableting initiated eutexia which enhanced dissolution of NSAIDs. Eutexia was associated with tablet softening in case of low melting point ketoprofen and aceclofenac. Wet granulation hastened eutexia developing unacceptable tablet in case ketoprofen and aceclofenac. Tablets prepared by direct compression of physical mixtures underwent gradual eutectic transition upon storage with the magnitude of eutectic transition reducing with increased melting point of NSAIDs. Ketoprofen was physically unstable but aceclofenac degraded chemically as well. Tenoxicam and meloxicam tablets were physically and chemically stable. Direct compression after physical mixing is the best tableting technique, but low melting point drugs should consider different strategy before compression.

Bioactive Protein and Peptide Release from a Mucoadhesive Electrospun Membrane

Protein-based biologics constitute a rapidly expanding category of therapeutic agents with high target specificity. Their clinical use has dramatically increased in recent years, but administration is largely via injection. Drug delivery across the oral mucosa is a promising alternative to injections, in order to avoid the gastrointestinal tract and first-pass metabolism. Current drug delivery formulations include liquid sprays, mucoadhesive tablets and films, which lack dose control in the presence of salivary flow. To address this, electrospun membranes that adhere tightly to the oral mucosa and release drugs locally have been developed. Here, we investigated the suitability of these mucoadhesive membranes for peptide or protein release. Bradykinin (0.1%) or insulin (1, 3, and 5%) were incorporated by electrospinning from ethanol/water mixtures. Immersion of membranes in buffer resulted in the rapid release of bradykinin, with a maximal release of 70 ± 12% reached after 1 h. In contrast, insulin was liberated more slowly, with 88 ± 11, 69.0 ± 5.4, and 63.9 ± 9.0% cumulative release of the total encapsulated dose after 8 h for membranes containing 1, 3, and 5% w/w insulin, respectively. Membrane-eluted bradykinin retained pharmacological activity by inducing rapid intracellular calcium release upon binding to its cell surface receptor on oral fibroblasts, when examined by flow cytometry. To quantify further, time-lapse confocal microscopy revealed that membrane-eluted bradykinin caused a 1.58 ± 0.16 fold-change in intracellular calcium fluorescence after 10 s compared to bradykinin solution (2.13 ± 0.21), relative to placebo. In conclusion, these data show that electrospun membranes may be highly effective vehicles for site-specific administration of biotherapeutic proteins or peptides directly to the oral mucosa for either local or systemic drug delivery applications.

Technological Aspects and Evaluation Methods for Polymer Matrices as Dental Drug Carriers

The development of polymer matrices as dental drug carriers takes into account the following technological aspects of the developed formulations: the composition and the technology used to manufacture them, which affect the properties of the carriers, as well as the testing methods for assessing their behavior at application sites. The first part of this paper characterizes the methods for fabricating dental drug carriers, i.e., the solvent-casting method (SCM), lyophilization method (LM), electrospinning (ES) and 3D printing (3DP), describing the selection of technological parameters and pointing out both the advantages of using the mentioned methods and their limitations. The second part of this paper describes testing methods to study the formulation properties, including their physical and chemical, pharmaceutical, biological and in vivo evaluation. Comprehensive in vitro evaluation of carrier properties permits optimization of formulation parameters to achieve prolonged retention time in the dynamic oral environment and is essential for explaining carrier behavior during clinical evaluation, consequently enabling the selection of the optimal formulation for oral application.

Buccal delivery of small molecules and biologics: Of mucoadhesive polymers, films, and nanoparticles - An update

Buccal delivery of small and large molecules is an attractive route of administration that has been studied extensively over the past few decades. This route bypasses first-pass metabolism and can be used to deliver therapeutics directly to systemic circulation. Moreover, buccal films are efficient dosage forms for drug delivery due to their simplicity, portability, and patient comfort. Films have traditionally been formulated using conventional techniques, including hot-melt extrusion and solvent casting. However, newer methods are now being exploited to improve the delivery of small molecules and biologics. This review discusses recent advances in buccal film manufacturing, using the latest technologies, such as 2D and 3D printing, electrospraying, and electrospinning. This review also focuses on the excipients used in the preparation of these films, with emphasis on mucoadhesive polymers and plasticizers. Along with advances in manufacturing technology, newer analytical tools have also been used for the assessment of permeation of the active agents across the buccal mucosa, the most critical biological barrier and limiting factor of this route. Additionally, preclinical and clinical trial challenges are discussed, and some small molecule products already on the market are explored.

Electrospun Mucoadhesive Zein/PVP Fibroporous Membrane for Transepithelial Delivery of Propranolol Hydrochloride

Mucoadhesive drug delivery systems have been extensively studied to effectively reduce the limitations of conventional drug delivery systems. Zein and polyvinyl pyrrolidone (PVP) are appraised for mucoadhesive properties. This study focuses on developing a mechanically stable zein/PVP electrospun membrane for propranolol hydrochloride (PL) transport. Fourier transform infrared, Raman spectra, and swelling studies gave evidence for PVP crosslinking, whereas circular dichroism spectroscopy revealed crosslinking of zein owing to the conformational change from α-helix to β-sheet. A 10 h thermal treatment of zein/PVP imparted 3.92 ± 0.13 MPa tensile strength to the matrix. Thermally crosslinked electrospun zein/PVP matrix showed 22.1 ± 0.1 g mm work of adhesion in porcine buccal mucosa tissue. Qualitative and quantitative evaluation of cytotoxicity in RPMI 2650 has been carried out. The in vitro drug release profile of PL from thermally crosslinked zein/PVP best fitted with the Korsmeyer-Peppas model. Immunostaining of β-catenin adherens junctional protein confirmed the absence of paracellular transport through the junctional opening. Still, drug permeation was observed through the porcine buccal mucosa, attributed to the transcellular transport of PL owing to its lipophilicity. The ex vivo permeation of PL through porcine buccal mucosa was also evaluated.

Polymeric Biomaterials for Topical Drug Delivery in the Oral Cavity: Advances on Devices and Manufacturing Technologies

There are several routes of drug administration, and each one has advantages and limitations. In the case of the topical application in the oral cavity, comprising the buccal, sublingual, palatal, and gingival regions, the advantage is that it is painless, non-invasive, allows easy application of the formulation, and it is capable of avoiding the need of drug swallowing by the patient, a matter of relevance for children and the elderly. Another advantage is the high permeability of the oral mucosa, which may deliver very high amounts of medication rapidly to the bloodstream without significant damage to the stomach. This route also allows the local treatment of lesions that affect the oral cavity, as an alternative to systemic approaches involving injection-based methods and oral medications that require drug swallowing. Thus, this drug delivery route has been arousing great interest in the pharmaceutical industry. This review aims to condense information on the types of biomaterials and polymers used for this functionality, as well as on production methods and market perspectives of this topical drug delivery route.

A method for evaluating drug penetration and absorption through isolated buccal mucosa with highly accuracy and reproducibility

The purpose of the project is to establish a standardized operation method of the in vitro permeability model to maximize mucosal integrity and viability. The model drug lidocaine permeability, 20 kDa fluorescein isothiocyanate-dextran, H&E staining, and mucosal viability were used as evaluation indicators. Firstly, the buccal mucosae of rats, rabbits, dogs, porcine, and humans were analyzed by H&E staining and morphometric analysis to compare the differences. Then, we studied a series of operation methods of isolated mucosa. The buccal mucosae were found to retain their integrity in Kreb's bicarbonate ringer solution at 4 °C for 36 h. Under the long-term storage method with program cooling, freezing at -80 °C, thawing at 37 °C, and using cryoprotectants of 20% glycerol and 20% trehalose, mucosal integrity and biological viability can be maintained for 21 days. The heat separation method was used to prepare a permeability model with a mucosal thickness of 500 μm, which was considered to be the optimal operation. In summary, this study provided an experimental basis for the selection and operation of in vitro penetration models, standardized the research process of isolated mucosa, and improved the accuracy of permeability studies.

Advances in the Application of Electrospun Drug-Loaded Nanofibers in the Treatment of Oral Ulcers

Oral ulcers affect oral and systemic health and have high prevalence in the population. There are significant individual differences in the etiology and extent of the disease among patients. In the treatment of oral ulcers, nanofiber films can control the drug-release rate and enable long-term local administration. Compared to other drug-delivery methods, nanofiber films avoid the disadvantages of frequent administration and certain side effects. Electrospinning is a simple and effective method for preparing nanofiber films. Currently, electrospinning technology has made significant breakthroughs in energy-saving and large-scale production. This paper summarizes the polymers that enable oral mucosal adhesion and the active pharmaceutical ingredients used for oral ulcers. Moreover, the therapeutic effects of currently available electrospun nanofiber films on oral ulcers in animal experiments and clinical trials are investigated. In addition, solvent casting and cross-linking methods can be used in conjunction with electrospinning techniques. Based on the literature, more administration systems with different polymers and loading components can be inspired. These administration systems are expected to have synergistic effects and achieve better therapeutic effects. This not only provides new possibilities for drug-loaded nanofibers but also brings new hope for the treatment of oral ulcers.

SEDDS-loaded mucoadhesive fiber patches for advanced oromucosal delivery of poorly soluble drugs

To date, buccal administration of lipophilic drugs is still a major challenge due to their poor solubility in saliva and limited penetration into mucosal tissues. To overcome these limitations, we developed electrospun patches combining the benefits of mucoadhesive fibers and self-emulsifying drug delivery systems (SEDDS). The fiber system comprises a combination of mucoadhesive thiolated polyacrylic acid fibers and SEDDS-loaded fibers fabricated by parallel electrospinning. The resulting mucoadhesive electrospun SEDDS patches were systemically investigated for fiber characteristics, self-emulsification, mucoadhesion, drug penetration into porcine buccal tissue and biocompatibility. The patches showed high encapsulation efficiency for SEDDS without causing fiber defects or leakage. SEDDS incorporation enhanced the spinning process and reduced the fiber diameter and fiber size distribution. Hydration-dependent self-emulsification provided a controlled release of curcumin being encapsulated in nano-scaled o/w emulsion for over 3 h. Due to the thiolated polyacrylic acid fibers, the buccal residence time of patches was 200-fold prolonged. Further, they promoted a significantly increased drug penetration into buccal tissue compared to fiber patches without SEDDS. Finally, biocompatibility and improved therapeutic effects of curcumin-loaded patches on human keratinocytes and fibroblasts were confirmed. Mucoadhesive electrospun SEDDS patches represent a promising approach to overcome current challenges in the oromucosal delivery of lipophilic drugs to unlock their full therapeutic potential.

Bile acid linked β-glucan nanoparticles for liver specific oral delivery of biologics

Oral delivery remains one of the most convenient routes for drug administration compared to intravenous, intramuscular, and via suppositories. However, due to the risk of degradation, and proteolysis of molecules in the acidic gastric medium, as well as the difficulty of transporting large molecules through the intestinal membrane, more than half of the therapeutic molecules are prohibited for oral administration. Moreover, most of the large molecules and biological therapeutics are not available in oral dosage form due to their instability in the stomach and inability of intestinal absorption. To achieve expected bioavailability, an orally administered therapeutic molecule must be protected within the stomach, and transportation facilitated via the small intestine. In this project, we have introduced a hybrid carrier, composed of Taurocholic Acid (TA) and β-Glucan (TAG), that is shown to be effective for the simultaneous protection of the biologics in acidic buffer and simulated gastric juice as well as facilitate enhanced absorption and transportation via the small intestine. In this project, we have used an eGFP encoded plasmid as a model biologic to prepare particles mediated with TAG. TAG show the potential of enhancing transfection and expression of eGFP as we have observed two fold higher expression in the cell upon coincubation for 4 h. In vivo studies on orally dosed mice showed that eGFP expression in the liver was significantly higher in TAG containing particles compared to particles without TAG. The findings suggest that the TAG carrier is capable of not only preserving biologics but also transporting them more efficiently to the liver. As a result, this strategy can be employed for a variety of liver-targeted therapeutic delivery to treat a variety of liver diseases.

Effect of Stellate Ganglion Block Combined with Lidocaine at Different Concentrations for Preemptive Analgesia on Postoperative Pain Relief and Adverse Reactions of Patients Undergoing Laparoscopic Cholecystectomy

Objective

To explore the effect of stellate ganglion block (SGB) combined with lidocaine at different concentrations for preemptive analgesia on postoperative pain relief and adverse reactions of patients undergoing laparoscopic cholecystectomy (LC).

Methods

Ninety patients undergoing LC in our hospital from June 2019 to June 2020 were selected as the subjects and were randomly divided into group A (30 cases), group B (30 cases), and group C (30 cases), all patients received SGB, and 10 mL of lidocaine at concentrations of 0.25%, 0.5%, and 0.75% was, respectively, administered to patients in groups A, B, and C, so as to compare the analgesic effect, adverse reactions, and clinical indicators among the three groups.

Results

At T₁ and T₂, group C obtained obviously lower NRS scores than groups A and B (P < 0.001); compared with groups A and B, group A had obviously higher onset time (P < 0.001) and significantly lower duration (P < 0.001); no obvious differences in the hemodynamic indexes among the groups were observed (P > 0.05); group C obtained obviously higher BCS score than groups A and B; and the total incidence rate of adverse reactions was obviously higher in group C than in groups A and B (P < 0.05).

Conclusion

Performing SGB combined with 0.5% lidocaine to patients undergoing LC achieves the optimal analgesic effect; such anesthesia plan can effectively stabilize patients' hemodynamics, present higher safety, and promote the regulation of the body internal environment. Further research will be conducive to establishing a better anesthesia plan for such patients.

Recent advances in polymer scaffolds for biomedical applications

The review provides insights into current advancements in electrospinning-assisted manufacturing for optimally designing biomedical devices for their prospective applications in tissue engineering, wound healing, drug delivery, sensing, and enzyme immobilization, and others. Further, the evolution of electrospinning-based hybrid biomedical devices using a combined approach of 3 D printing and/or film casting/molding, to design dimensionally stable membranes/micro-nanofibrous assemblies/patches/porous surfaces, etc. is reported. The influence of various electrospinning parameters, polymeric material, testing environment, and other allied factors on the morphological and physico-mechanical properties of electrospun (nano-/micro-fibrous) mats (EMs) and fibrous assemblies have been compiled and critically discussed. The spectrum of operational research and statistical approaches that are now being adopted for efficient optimization of electrospinning process parameters so as to obtain the desired response (physical and structural attributes) has prospectively been looked into. Further, the present review summarizes some current limitations and future perspectives for modeling architecturally novel hybrid 3 D/selectively textured structural assemblies, such as biocompatible, non-toxic, and bioresorbable mats/scaffolds/membranes/patches with apt mechanical stability, as biological substrates for various regenerative and non-regenerative therapeutic devices.

Fabrication of multifunctional mucoadhesive buccal patch for drug delivery applications

Mucoadhesive buccal patch is a promising dosage form for a successful oral drug delivery, which provides unique advantages for various applications such as treatment of periodontal disease and postdental surgery disorders. The aim of this study is to synthesize a novel multifunctional mucoadhesive buccal patch in a multilayer reservoir design for therapeutic applications. The patches were fabricated through simultaneous electrospinning of chitosan/poly(vinylalcohol) (PVA)/ibuprofen and electrospraying of phenylalanine amino acid nanotubes (PhNTs) containing metronidazole into the electrospun mats through a layer-by-layer process. An electrospun poly(caprolactone) (PCL) was used as an impermeable backing layer to protect the mucoadhesive component from tongue movement and drug loss. Buccal patches were characterized using scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM) and also evaluated in terms of physicomechanical parameters such as pH, weight, thickness, tensile strength, folding endurance, and mucoadhesive properties. The swelling index of the patches was examined with respect to the PVA/chitosan ratio. The effect of genipin addition to the electrospinning solution was also studied on mucoadhesive and swelling properties. The cell viability of buccal patches was assessed by methylthiazolydiphenyl-tetrazolium bromide test on L929 fibroblast cell line. The patch with an optimal amount of mucoadhesive polymers (PVA/chitosan 80:20) and crosslinking agent (0.05 g) indicated an ideal hemostatic activity along with antibacterial properties against Streptococcus mutans bacteria. The synthesized multifunctional mucoadhesive patch with a novel composition and design has a great potential for oral therapeutic applications.

Manufacturing and characterisation of a novel composite dosage form for buccal drug administration

The potential of alternative routes of application compared to the traditional oral route is constantly growing. Especially in transmucosal applications for the oral cavity, easy accessibility is an attractive feature with many new opportunities. The combination of a minitablet and a buccal mucoadhesive carrier film has been shown to enable safe and accurate drug administration compared to semi-solid formulations currently available on the market. In order to investigate these so-called composite dosage forms in more detail, two different manufacturing methods were compared within this study to investigate the resulting properties. The formulation development of the minitablets containing lidocaine, complying with the compendial requirements, resulted in immediate release using both manufacturing methods (more than 80% lidocaine release after 3-4 min using direct incorporation, 7-8 min by the gluing method). Differences in morphology and drug migration behaviour could be observed. The directly incorporated minitablets revealed a twofold higher drug migration (1.5 mm) into the mucoadhesive shielding film within two weeks compared to the glued minitablets (0.8 mm). These findings enable a further optimization of the formulation depending on the duration of the application and the feasibility for the addressed patient population.

Mucoadhesive Electrospun Fibre-Based Technologies for Oral Medicine

Oral disease greatly affects quality of life, as the mouth is required for a wide range of activities including speech, food and liquid consumption. Treatment of oral disease is greatly limited by the dose forms that are currently available, which suffer from short contact times, poor site specificity, and sensitivity to mechanical stimulation. Mucoadhesive devices prepared using electrospinning offer the potential to address these challenges by allowing unidirectional site-specific drug delivery through intimate contact with the mucosa and with high surface areas to facilitate drug release. This review will discuss the range of electrospun mucoadhesive devices that have recently been reported to address oral inflammatory diseases, pain relief, and infections, as well as new treatments that are likely to be enabled by this technology in the future.

Fabrication of Mucoadhesive Buccal Films for Local Administration of Ketoprofen and Lidocaine Hydrochloride by Combining Fused Deposition Modeling and Inkjet Printing

In the area of developing oromucosal drug delivery systems, mucoadhesive buccal films are the most promising formulations for either systemic or local drug delivery. The current study presents the fabrication of buccal films, by combining fused deposition modeling (FDM) and inkjet printing. Hydroxypropyl methylcellulose-based films were fabricated via FDM, containing the non-steroidal anti-inflammatory drug ketoprofen. Unidirectional release properties were achieved, by incorporating an ethyl cellulose-based backing layer. The local anesthetic lidocaine hydrochloride, combined with the permeation enhancer l-menthol, was deposited onto the film by inkjet printing. Physicochemical analysis showed alterations in the characteristics of the films, and the mucoadhesive and mechanical properties were effectively modified, due to the ink deposition on the substrates. The in vitro release data of the active pharmaceutical compounds, as well as the permeation profiles across ex vivo porcine buccal mucosa and filter-grown TR146 cells of human buccal origin, were associated with the presence of the permeation enhancer and the backing layer. The lack of any toxicity of the fabricated films was demonstrated by the MTT viability assay. This proof-of-concept study provides an alternative formulation approach of mucoadhesive buccal films, intended for the treatment of local oromucosal diseases or systemic drug delivery.

Medium-Chain Fatty Acids Released from Polymeric Electrospun Patches Inhibit Candida albicans Growth and Reduce the Biofilm Viability

Oral candidiasis is a very common oral condition among susceptible individuals, with the main causative organism being the fungus Candida albicans. Current drug delivery systems to the oral mucosa are often ineffective because of short drug/tissue contact times as well as increased prevalence of drug-resistant Candida strains. We evaluated the potency of saturated fatty acids as antifungal agents and investigated their delivery by novel electrospun mucoadhesive oral patches using agar disk diffusion and biofilm assays. Octanoic (C8) and nonanoic (C9) acids were the most effective at inhibiting C. albicans growth on disk diffusion assays, both in solution or when released from polycaprolactone (PCL) or polyvinylpyrrolidone/RS100 (PVP/RS100) electrospun patches. In contrast, dodecanoic acid (C12) displayed the most potent antifungal activity against pre-existing C. albicans biofilms in solution or when released by PCL or PVP/RS100 patches. Both free and patch-released saturated fatty acids displayed a significant toxicity to wild-type and azole-resistant strains of C. albicans. These data not only provide evidence that certain saturated fatty acids have the potential to be used as antifungal agents but also demonstrate that this therapy could be delivered directly to Candida-infected sites using electrospun mucoadhesive patches, demonstrating a potential new therapeutic approach to treat oral thrush.

Swelling of mucoadhesive electrospun chitosan/polyethylene oxide nanofibers facilitates adhesion to the sublingual mucosa

Mucoadhesive chitosan-based electrospun nanofibers are promising candidates for overcoming challenges associated with sublingual drug delivery, yet studies focusing on evaluating the mucoadhesive properties of nanofibers for sublingual administration are limited. The aim was to elucidate the mucoadhesive properties of chitosan/polyethylene oxide (PEO) nanofibers focusing on how the degree of deacetylation (DDA, 53-96 %) of chitosan influenced their morphological and mucoadhesive properties. The mechanism of mucoadhesion was explained by the intermolecular interactions of chitosan with mucin from bovine submaxillary glands using quartz-crystal microbalance with dissipation monitoring and by adhesion of the nanofibers to ex vivo porcine sublingual mucosa. An increase in chitosan DDA improved the morphological stability of the nanofibers in water, but did not contribute to altered mucoadhesive properties. This study demonstrates excellent mucoadhesive properties of chitosan/PEO nanofibers and shows that the strong mucoadhesiveness of the nanofibers is attributed to their swelling ability.