Towards the advance of a novel iontophoretic patch for needle-free buccal anesthesia

Emerging trends in designing polysaccharide based mucoadhesive network hydrogels as versatile platforms for innovative delivery of therapeutic agents: A review

INTRODUCTION

The rapid progress in polymer science has designed innovative materials for biomedical applications. In the case of drug design, for each new therapeutic agent, a drug delivery system (DDS) is required to improve its pharmacokinetic and pharmacodynamic parameters. Therefore, significant research has been carried out to develop drug delivery (DD) carriers for these new therapeutic agents. Hydrogels have been explored as potential candidates to prepare controlled drug delivery (CDD) systems to address the challenges related to the performance of the conventional DD formulations. Mucoadhesive drug delivery system (MUCO-DDS) is a specialized form of CDD system, facilitating site-specific DD, protecting the drug from first pass metabolism and enhancing its overall bioavailability.

METHODS

The present article provides a comprehensive discussion of the synthesis, properties and applications of polysaccharide-derived MUCO-DDS. Different natural polymer-derived MUCO-DDS including chitosan, alginate, pectin, xanthan gum, psyllium, gelatin, cellulose, hyaluronic acid, guar gum, sterculia gum and tragacanth gum have been reported. Herein, these DDS were elaborately discussed along with their applications and future-prospective. These DDS are classified on the basis of drug administration (nasal, ocular, vagina/rectal & buccal DDS) and drug distribution (reservoir and monolithic polymer matrix). Factors contributing to modifications of properties of MUCO-DDS were also demonstrated along with different stages and theories of mucoadhesion.

RESULTS

Polysaccharides exhibit properties such as biocompatibility, biodegradability, and flexibility, making them ideal for CDD applications. MUCO-DDS demonstrates several significant advantages. Moreover, the article bridges theoretical insights with practical applications and future research prospects, ensuring its relevance for advancements in the concerned field. This review serves as a comprehensive resource, addressing gaps in previous literature and paving the way for innovations in MUCO-DDS, through a comparative analysis of the advantages, limitations, and modifications of natural polymers.

CONCLUSIONS

In conclusion, this review gives an overview of the current developments in the field of mucoadhesive DD systems and also gives insights into the future perspectives. The MUCOAD of DDS could be modulated by the inclusion of various natural and synthetic components in hydrogels. Future directions for the researchers are underway to integrate nanotechnology with mucoadhesive systems to create hybrid platforms. Overall, by addressing current limitations and leveraging emerging technologies, these systems can revolutionize drug delivery for a wide range of therapeutic applications.

Allergic Reactions in Dental Practice: Classification of Medicines, Mechanisms of Action, and Clinical Manifestations

Allergic reactions in dental practice have been a serious problem, causing various clinical symptoms and having a significant impact on the quality of dental care. This study examined various aspects of allergic reactions, their causes, mechanisms of development, and prevalence in dental practice. The purpose of the study was to conduct a comprehensive analysis of allergic reactions, their classification, clinical manifestations, and mechanisms of development, and to identify the most common causes of such reactions. To achieve this goal, a systematic literature review was conducted. As a result of the study, different types of allergic reactions and mechanisms of their development were identified. Among them, special attention was paid to immediate hypersensitivity reactions mediated by immunoglobulin E (IgE). Delayed-type reactions mediated by sensitised T lymphocytes were also considered. Pseudoallergic reactions occupied a separate place in the classification of allergic reactions. The study emphasised the importance of cross-reactions, in which several structurally similar molecules bind to the same IgE antibodies or T lymphocytes. The main results of the study showed that allergic reactions can be triggered by a variety of allergens. Prominent among these were local anaesthetics such as lidocaine and benzocaine, antibiotics including penicillins and cephalosporins, latex products such as gloves and cofferdams, acrylic materials used in dental prostheses and fillings, and metal alloys containing nickel, chromium, and cobalt. The study has contributed to a better understanding of the factors causing allergic reactions in dental practice and the mechanisms of their development. This is important for improving the diagnosis and management of such cases, thereby improving the quality of dental care provided.

Assessing α-Bisabolol as a Transmucosal Permeation Enhancer of Buccal Local Anesthetics

Needle-free buccal anesthesia improves dental treatment outcomes for both patients and dentists. In this study, we report on an assessment of the enhancement effects of α-bisabolol on the in vitro transmucosal permeation of prilocaine hydrochloride (PCl) and lidocaine hydrochloride (LCl) from needleless buccal films. We also evaluated the mechanical properties of the film, which consisted of Methocel™ K100 LV as the film-forming polymer (3% m·m-1), PEG 400 as a cosolvent (15% m·m-1 based on drug loading), α-bisabolol (15 and 30% m·m-1 based on drug loading), and the drugs combined at a 1:1 ratio (15 mg·unit-1). The porcine esophageal epithelium was used as a membrane barrier, and artificial saliva was the release medium. After a 1 h experiment at 25 ± 2 °C, α-bisabolol significantly decreased, rather than enhanced, the permeation fluxes (five-fold), permeability coefficients (seven-fold), and retentions (two-fold) of both PCl and LCl through the epithelium, regardless of the concentration. Moreover, the resistance and flexibility of the films markedly decreased compared to those without α-bisabolol. Therefore, under the experimental conditions, using α-bisabolol as a buccal permeation enhancer for the hydrophilic local anesthetics PCl and LCl from buccal films is not feasible.

Challenges in Optimizing Nanoplatforms Used for Local and Systemic Delivery in the Oral Cavity

In this study, we focused on innovative approaches to improve drug administration in oral pathology, especially by transmucosal and transdermal pathways. These improvements refer to the type of microneedles used (proposing needles in the saw), to the use of certain enhancers such as essential oils (which, besides the amplifier action, also have intrinsic actions on oral health), to associations of active substances with synergistic action, as well as the use of copolymeric membranes, cemented directly on the tooth. We also propose a review of the principles of release at the level of the oral mucosa and of the main release systems used in oral pathology. Controlled failure systems applicable in oral pathology include the following: fast dissolving films, mucoadhesive tablets, hydrogels, intraoral mucoadhesive films, composite wafers, and smart drugs. The novelty elements brought by this paper refer to the possibilities of optimizing the localized drug delivery system in osteoarthritis of the temporomandibular joint, neuropathic pain, oral cancer, periodontitis, and pericoronitis, as well as in maintaining oral health. We would like to mention the possibility of incorporating natural products into the controlled failure systems used in oral pathology, paying special attention to essential oils.

Intraoral medical devices for sustained drug delivery

OBJECTIVES

The oral cavity constitutes an attractive organ for the local and systemic application of drug substances. Oromucosal tablets, gels, or sprays are examples of the formulations applied. Due to the elution through the saliva, the residence time of the formulation at the application site is relatively short. Medical devices placed in the oral cavity, with a reservoir for an active substance, play an important role in solving this problem.

MATERIALS AND METHODS

In this review, we discuss the devices described in the literature that are designed to be used in the oral cavity, highlighting the advantages, disadvantages, and clinical applications of each of them.

RESULTS

Among the intraoral medical devices, special types are personalized 3D-printed devices, iontophoretic devices, and microneedle patches.

CONCLUSION

We anticipate that with the development of 3D printing and new polymers, the technology of flexible and comfortable devices for prolonged drug delivery in the oral cavity will develop intensively.

CLINICAL RELEVANCE

The presented review is therefore a useful summary of the current technological state, when in fact none of the existing devices has been widely accepted clinically.

Clinical Efficacy and Safety of Lidocaine Tape for Topical Anesthesia of the Oral Mucosa: A Preliminary Controlled Trial

Local anesthesia is administered to reduce pain-induced stress during dental treatment. However, local anesthetic injections are extremely painful; thus, methods to minimize this pain should be developed. Clinical studies on the pain-relieving effects of dental topical anesthetics have shown that few topical anesthetics provide fast and adequate pain relief without harming the oral mucosa. We examined the efficacy and safety of lidocaine tape, which has a potent topical anesthetic effect. Lidocaine tape was applied to the oral mucosa of 14 healthy participants, and its suppression effect was assessed by examining the pain intensity at the non-lidocaine tape-applied site using the visual analog evaluation scale and the verbal evaluation scale. Lidocaine tape application significantly reduced visual analog scale (VAS) scores during mucosal puncture compared to non-application (p < 0.01). Moreover, lidocaine tape application significantly reduced VAS scores during local anesthetic injection compared to non-application (p < 0.001). Adverse events were evaluated using the Common Terminology Criteria for Adverse Events, version 5.0. No adverse events attributed to the application of lidocaine tape were observed in any participant. The findings in this study suggest that the application of lidocaine tape before infiltration anesthesia can reduce patient distress.

The Potential of Films as Transmucosal Drug Delivery Systems

Pharmaceutical films are polymeric formulations used as a delivery platform for administration of small and macromolecular drugs for local or systemic action. They can be produced by using synthetic, semi-synthetic, or natural polymers through solvent casting, electrospinning, hot-melt extrusion, and 3D printing methods, and depending on the components and the manufacturing methods used, the films allow the modulation of drug release. Moreover, they have advantages that have drawn interest in the development and evaluation of film application on the buccal, nasal, vaginal, and ocular mucosa. This review aims to provide an overview of and critically discuss the use of films as transmucosal drug delivery systems. For this, aspects such as the composition of these formulations, the theories of mucoadhesion, and the methods of production were deeply considered, and an analysis of the main transmucosal pathways for which there are examples of developed films was conducted. All of this allowed us to point out the most relevant characteristics and opportunities that deserve to be taken into account in the use of films as transmucosal drug delivery systems.

Three-Dimensional-Printed Oral Films Based on LCD: Influence Factors of the Film Printability and Received Qualities

As an oral mucosal drug delivery system, oral films have been of wide concern in recent years because of their advantages such as rapid absorption, being easy to swallow and avoiding the first-pass effect common for mucoadhesive oral films. However, the currently utilized manufacturing approaches including solvent casting have many limitations, such as solvent residue and difficulties in drying, and are not suitable for personalized customization. To solve these problems, the present study utilizes liquid crystal display (LCD), a photopolymerization-based 3D printing technique, to fabricate mucoadhesive films for oral mucosal drug delivery. The designed printing formulation includes PEGDA as the printing resin, TPO as the photoinitiator, tartrazine as the photoabsorber, PEG 300 as the additive and HPMC as the bioadhesive material. The influence of printing formulation and printing parameters on the printing formability of the oral films were elucidated in depth, and the results suggested that PEG 300 in the formulation not only provided the necessary flexibility of the printed oral films, but also improved drug release rate due to its role as pore former in the produced films. The presence of HPMC could greatly improve the adhesiveness of the 3D-printed oral films, but excessive HPMC increased the viscosity of the printing resin solution, which could strongly hinder the photo-crosslinking reaction and reduce printability. Based on the optimized printing formulation and printing parameters, the bilayer oral films containing a backing layer and an adhesive layer were successfully printed with stable dimensions, adequate mechanical properties, strong adhesion ability, desirable drug release and efficient in vivo therapeutic efficacy. All these results indicated that an LCD-based 3D printing technique is a promising alternative to precisely fabricate oral films for personalized medicine.

Off-label pharmacological treatment for neuropathic pain: A Delphi study by the Spanish Pain Society Neuropathic Pain Task Force

OBJECTIVES

The use of off-label pharmacotherapies for neuropathic pain (NP) is growing relating to the many unmet needs of patients. However, clinical guidelines fail to address it, and the available evidence is sparse and fragmented. We arranged a formal expert consensus to address this controversial issue and provide some guidance on judicious use.

METHODS

A two-round standard Delphi survey that involved pain clinic specialists with experience in the research and management of NP was done over an ad hoc 40-item questionnaire prepared by the authors. Consensus on each statement was defined as at least either 80% endorsement or rejection after the second round.

RESULTS

Forty-three and thirty-seven panelists participated in the first and second round, respectively. Consensus was reached in 34 out of 40 statements. Endorsed alternatives for unresponsive patients include non-gabapentinoid antiepileptics (oxcarbazepine and eslicarbazepine), venlafaxine, intravenous lidocaine (when doses can be optimized), and some vaporized cannabinoids (under appropriate surveillance). In addition, lacosamide, low-dose naltrexone, propofol, or ketamine could prove beneficial if subjected to more research. Other options were rejected, and there was controversy about the usefulness of topical preparations.

DISCUSSION

For patients who do not respond to standard NP treatments, some other viable pharmacological options can be attempted before advancing to other therapeutic stages. This may help patients who are reluctant to or have some contraindication for interventional therapies.

Buccal Permeation of Polysaccharide High Molecular Weight Compounds: Effect of Chemical Permeation Enhancers

The greatest achievement in the advanced drug delivery field should be the optimization of non-invasive formulations for the delivery of high molecular weight compounds. Peptides, proteins, and other macromolecules can have poor membrane permeation, principally due to their large molecular weight. The aim of this work was to explore the possibility of administering fluorescently labeled dextrans (molecular weight 4-150 kDa) across the buccal mucosa. Permeation experiments across pig esophageal mucosa were carried out using fatty acids and bile salts as penetration enhancers. The data obtained show that it is possible to increase or promote the mucosa permeation of high molecular weight dextrans by using caprylic acid or sodium taurocholate as the chemical enhancers. With these enhancers, dextrans with molecular weight of 70 and 150 kDa, that in passive conditions did not permeate, could cross the mucosa in detectable amounts. FD-70 and FD-150 showed comparable permeability values, despite the molecular weight difference. The results obtained in the present work suggest that the buccal administration of high molecular weight compounds is feasible.

Needle-free anesthesia: clinical efficacy of a mucoadhesive patch for atraumatic anesthesia in dental procedures

This study showcases the clinical efficacy of mucoadhesive patches designed for the buccal delivery of lidocaine and prilocaine hydrochlorides (1:1, 30 mg/patch). Such patches were developed for needle-free pre-operative local anesthesia in dentistry, aiming at mitigating the use of infiltrative anesthesia for medium-complexity clinical procedures. The patches were manufactured encompassing drug-release, mucoadhesive and backing layers, all prepared through film casting using biocompatible materials. Fifty-eight (n = 58) adult patients (65% women and 35% men) were randomly selected and included in a one-arm open clinical prospective cohort study. The average age of the subjects was of 50 years. The majority (59%) of the subjects, mostly women (82%), reported needle-phobia or anxiety due to dental procedures, which was assessed through a questionnaire approved by the ethical council for human use in research. The patches were positioned in the gingival region of the teeth involved in the procedure (86% on the maxillary and 14% on the mandibular bone). Two anesthetic patches were applied on each patient: one in the vestibular region and another in the palate/lingual portion, and these patches remained attached to the placement sites throughout the procedures. Concerning the dental procedures performed, 40% were cavity preparations and dental restorations of medium cavities; 29% staple facilities; 10% gingival retractions; 9% subgingival scrapings; 3% gingivalplasties; 3% supragingival preparations; 3% occlusal adjustments; and 2% subgingival preparations. In 90% of the cases, it was not necessary to complement with conventional infiltrative local anesthesia during the procedures. Patients did not report any discomfort or side effect during or after the administration of the patches. Among the cases in which there was the need for complementation, 50% were cavity preparations and dental restorations; 33% supragingival preparations; and 17% gingivoplasties. The complementary anesthesia volume was of 0.63 ± 0.23 mL and women corresponded to 83% of the participants who needed such intervention. Furthermore, in most cases, the patch was capable of initiating the anesthesia within a short time frame (5 minutes) and reaching the maximum anesthetic effect within 15 and 25 min, lasting at least 50 min. Undesirable side effects were not reported either 2 h after the administration or within the 6-month follow-up. Therefore, the anesthetic patches developed provide needle-free, painless, safe, and patient/dentist-friendly advances in performing routine medium-complexity dental procedures.