Critical evaluation of permeation enhancers for oral mucosal drug delivery

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.

Gastrointestinal Permeation Enhancers Beyond Sodium Caprate and SNAC - What is Coming Next?

Oral peptide delivery is trending again. Among the possible reasons are the recent approvals of two oral peptide formulations, which represent a huge stride in the field. For the first time, gastrointestinal (GI) permeation enhancers (PEs) are leveraged to overcome the main limitation of oral peptide delivery-low permeability through the intestinal epithelium. Despite some success, the application of current PEs, such as salcaprozate sodium (SNAC), sodium caprylate (C8), and sodium caprate (C10), is generally resulting in relatively low oral bioavailabilities (BAs)-even for carefully selected therapeutics. With several hundred peptide-based drugs presently in the pipeline, there is a huge unmet need for more effective PEs. Aiming to provide useful insights for the development of novel PEs, this review summarizes the biological hurdles to oral peptide delivery with special emphasis on the epithelial barrier. It describes the concepts and action modes of PEs and mentions possible new targets. It further states the benchmark that is set by current PEs, while critically assessing and evaluating emerging PEs regarding translatability, safety, and efficacy. Additionally, examples of novel PEs under preclinical and clinical evaluation and future directions are discussed.

The dawning era of oral thin films for nutraceutical delivery: From laboratory to clinic

Oral thin films (OTFs) are innovative dosage forms that have gained tremendous attention for the delivery of nutraceuticals. They are ultra-thin, flexible sheets that can be easily placed on the tongue, sublingual or buccal mucosa (inner lining of the cheek). These thin films possess several advantages for nutraceutical delivery including ease of administration, rapid disintegration, fast absorption, rapid onset of action, bypass first-pass hepatic metabolism, accurate dosing, enhanced stability, portability, discreetness, dose flexibility and most importantly consumer acceptance. This review highlights the utilization OTFs for nutraceutical delivery, their composition, criteria for excipient selection, methods of development and quality-based design (QbD) approach to achieve quality product. We have also provided recent case studies representing OTFs as promising platform in delivery of nutraceuticals (plant extracts, bioactive molecules, vitamins, minerals and protein/peptides) and probiotics. Finally, we provided advancement in technologies, recent patents, market analysis, challenges and future perspectives associated with this unique dosage form.

Biopolymer Drug Delivery Systems for Oromucosal Application: Recent Trends in Pharmaceutical R&D

Oromucosal drug delivery, both local and transmucosal (buccal), is an effective alternative to traditional oral and parenteral dosage forms because it increases drug bioavailability and reduces systemic drug toxicity. The oral mucosa has a good blood supply, which ensures that drug molecules enter the systemic circulation directly, avoiding drug metabolism during the first passage through the liver. At the same time, the mucosa has a number of barriers, including mucus, epithelium, enzymes, and immunocompetent cells, that are designed to prevent the entry of foreign substances into the body, which also complicates the absorption of drugs. The development of oromucosal drug delivery systems based on mucoadhesive biopolymers and their derivatives (especially thiolated and catecholated derivatives) is a promising strategy for the pharmaceutical development of safe and effective dosage forms. Solid, semi-solid and liquid pharmaceutical formulations based on biopolymers have several advantageous properties, such as prolonged residence time on the mucosa due to high mucoadhesion, unidirectional and modified drug release capabilities, and enhanced drug permeability. Biopolymers are non-toxic, biocompatible, biodegradable and may possess intrinsic bioactivity. A rational approach to the design of oromucosal delivery systems requires an understanding of both the anatomy/physiology of the oral mucosa and the physicochemical and biopharmaceutical properties of the drug molecule/biopolymer, as presented in this review. This review summarizes the advances in the pharmaceutical development of mucoadhesive oromucosal dosage forms (e.g., patches, buccal tablets, and hydrogel systems), including nanotechnology-based biopolymer nanoparticle delivery systems (e.g., solid lipid particles, liposomes, biopolymer polyelectrolyte particles, hybrid nanoparticles, etc.).

Mucoadhesive Budesonide Solution for the Treatment of Pediatric Eosinophilic Esophagitis

Eosinophilic Esophagitis is an antigen-mediated inflammatory disease characterized by thickening of the esophageal wall, leading to dysphagia, vomiting, reflux, and abdominal pain. This disease can be treated with a therapeutic approach ranging from diet to pharmacological therapy. Jorveza® (budesonide) and Dupixent® (dupilumab) are treatments for Eosinophilic Esophagitis approved by the European Medicines Agency in adults but not in children. Budesonide-based extemporaneous oral liquid suspensions could be prepared for pediatric use. The main limit of this formulation is that budesonide needs a longer residence time on the esophageal mucosa to solubilize and diffuse in it to exert its local anti-inflammatory effect. Herein, we propose the development of an extemporaneous mucoadhesive oral budesonide solution for the pediatric population. A liquid vehicle containing hydroxypropyl-beta-cyclodextrin as a complexing agent and carboxymethylcellulose sodium as a mucoadhesive excipient was used to prepare budesonide-based formulations. A stable solution at a concentration of 0.7 mg/mL was successfully prepared and characterized. The formulation showed rheological and mucoadhesive properties suitable for an Eosinophilic Esophagitis local prolonged treatment. In this way, pharmacists can prepare stable budesonide-based mucoadhesive solutions, providing both patients and physicians with a new therapeutic option for Eosinophilic Esophagitis pediatric treatment.

Absorption enhancer approach for protein delivery by various routes of administration: a rapid review

As bioactive molecules, peptides and proteins are essential in living organisms, including animals and humans. Defects in their function lead to various diseases in humans. Therefore, the use of proteins in treating multiple diseases, such as cancers and hepatitis, is increasing. There are different routes to administer proteins, which have limitations due to their large and hydrophilic structure. Another limitation is the presence of biological and lipophilic membranes that do not allow proteins to pass quickly. There are different strategies to increase the absorption of proteins from these biological membranes. One of these strategies is to use compounds as absorption enhancers. Absorption enhancers are compounds such as surfactants, phospholipids and cyclodextrins that increase protein passage through the biological membrane and their absorption by different mechanisms. This review focuses on using other absorption enhancers and their mechanism in protein administration routes.

Beyond traditional therapy: Mucoadhesive polymers as a new frontier in oral cancer management

In recent times mucoadhesive drug delivery systems are gaining popularity in oral cancer. It is a malignancy with high global prevalence. Despite significant advances in cancer therapeutics, improving the prognosis of late-stage oral cancer remains challenging. Targeted therapy using mucoadhesive polymers can improve oral cancer patients' overall outcome by offering enhanced oral mucosa bioavailability, better drug distribution and tissue targeting, and minimizing systemic side effects. Mucoadhesive polymers can also be delivered via different formulations such as tablets, films, patches, gels, and nanoparticles. These polymers can deliver an array of medicines, making them an adaptable drug delivery approach. Drug delivery techniques based on these mucoadhesive polymers are gaining traction and have immense potential as a prospective treatment for late-stage oral cancer. This review examines leading research in mucoadhesive polymers and discusses their potential applications in treating oral cancer.

Development of a buccal in vitro permeation method - exploring aQbD implementation

The buccal mucosa is arising within the pharmaceutical landscape as an attractive option for local and systemic drug delivery, mostly due to its high vascularization, inherent permeability and robustness. Still, one of the major challenges in bringing oromucosal preparations to market remains the accurate evaluation of permeability. During pre-clinical drug development, in vitro permeation assessment is essential, and methodologies, based on the selection of a proper membrane in a diffusion cell, have become appealing alternatives to the conventional cell-based models. The development of such methods is being constrained by the number of variables - related to study conditions, setup and formulation - that need to be optimized to accurately estimate buccal permeation. The gap of knowledge over the mentioned variables may lead to long costly developments and poorly accurate methods, especially if the empirical analytical approach is used. In this paper, a systematic risk-based analytical quality by design approach was applied to the development of a buccal in vitro permeation method, ensuring that all sources of variability affecting permeation process were identified, explained and managed by appropriate measures. Researchers are guided through a step by step model, successfully demonstrating with experimental data the impact of critical variables on method's performance.

Oral Mucosa Models to Evaluate Drug Permeability

Due to its numerous advantages, such as excellent drug accessibility, rapid absorption, and bypass of first-pass metabolism, the route of drug administration that involves crossing the oral mucosa is highly favored. As a result, there is significant interest in investigating the permeability of drugs through this region. The purpose of this review is to describe the various ex vivo and in vitro models used to study the permeability of conveyed and non-conveyed drugs through the oral mucosa, with a focus on the most effective models. Currently, there is a growing need for standardized models of this mucosa that can be used for developing new drug delivery systems. Oral Mucosa Equivalents (OMEs) may provide a promising future perspective as they are capable of overcoming limitations present in many existing models.

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.

Oromucosal delivery of macromolecules: Challenges and recent developments to improve bioavailability

Owing to their biological diversity, high potency, good tolerability, low immunogenicity, site-specific activity, and great efficacy, macromolecular drugs (i.e., proteins and peptides, antibodies, hormones, nucleic acids, vaccines, etc.) are extensively used as diagnostics, prophylactics, and therapeutics in various diseases. To overcome drawbacks associated with parenteral (invasive) delivery of macromolecules as well as to preserve their therapeutic integrity, oromucosal route (sublingual and buccal) has been proven efficient alternate port of delivery. This review aims to summarize challenges associated with oromucosal route and overtime developments in conventional delivery systems with special emphasis on most recent delivery strategies. Over the past few decades, significant efforts have been made for improving the oromucosal absorption of macromolecules by employing chemical penetration enhancers (CPE), enzyme inhibitors, chemical modification of drug structure (i.e., lipidation, PEGylation, etc.), and mucoadhesive materials in the form of buccal tablets, films (or patches), sprays, fast disintegrating tablets, and microneedles. Adaptation of adjunct strategies (e.g., iontophoresis in conjunction with CPE) has shown significant improvement in oromucosal absorption of macromolecules; however, these approaches were also associated with many drawbacks. To overcome these shortcomings and to further improve therapeutic outcomes, specialized delivery devices called "hybrid nanosystems" have been designed in recent times. This newer intervention showed promising potential for promoting oromucosal absorption and absolute bioavailability of macromolecules along with improved thermostability (cold chain free storage), enabling self-administration, site-specific activity, improving therapeutic efficacy and patient compliance. We anticipate that tailoring of hybrid nanosystems to clinical trials as well as establishing their short- and long-term safety profile would substantiate their therapeutic value as pharmaceutical devices for oromucosal delivery of macromolecules.

In Vitro Release, Mucosal Permeation and Deposition of Cannabidiol from Liquisolid Systems: The Influence of Liquid Vehicles

This work investigated the influence of liquid vehicles on the release, mucosal permeation and deposition of cannabidiol (CBD) from liquisolid systems. Various vehicles, including EtOH, nonvolatile low- and semi-polar solvents, and liquid surfactants, were investigated. The CBD solution was converted into free-flowing powder using carrier (microcrystalline cellulose) and coating materials (colloidal silica). A physical mixture of the CBD and carrier–coating materials was prepared as a control. The non-crystalline state of CBD in the liquisolid systems was confirmed using XRD, FTIR and SEM studies. The CBD liquisolid powder prepared with volatile and nonvolatile solvents had a better CBD release performance than the CBD formed as the surfactant-based and control powders. The liquisolid systems provided the CBD permeation flux through porcine esophageal mucosa ranging from 0.68 ± 0.11 to 13.68 ± 0.74 µg·cm⁻²·h⁻¹, with the CBD deposition levels of 0.74 ± 0.04 to 2.62 ± 0.30 μg/mg for the dry mucosa. Diethylene glycol monoethyl ether showed significant CBD permeation enhancement (2.1 folds) without an increase in mucosal deposition, while the surfactants retarded the permeation (6.7–9.0 folds) and deposition (1.5–3.2 folds) significantly. In conclusion, besides the drug release, liquid vehicles significantly influence mucosal permeation and deposition, either enhanced or suppressed, in liquisolid systems. Special attention must be paid to the selection and screening of suitable liquid vehicles for liquisolid systems designed for transmucosal applications.

Mucosal Delivery of Cannabidiol: Influence of Vehicles and Enhancers

In this study, the mucosal permeation and deposition of cannabidiol (CBD) with neat and binary vehicles were investigated. Permeation experiments were performed using static diffusion cells coupled with fresh porcine esophageal mucosa. The CBD-vehicle solutions were applied at a fixed dose (~5 mg/cm²), and the corresponding permeation parameters were calculated. In neat vehicles, the permeation flux (J_ss) ranged from 0.89 ± 0.15 to 179.81 ± 23.46 µg·cm^-2·h^-1, while the CBD deposition ranged from 11.5 ± 1.8 to 538.3 ± 105.3 μg·cm^-2. Propylene glycol (PG) and diethylene glycol monoethyl ether (DEGEE) yielded the highest permeability (P_s) and CBD deposition, while medium-chain triglycerides (MCT) yielded the lowest P_s and deposition. This was due to the difference in apparent partition coefficient (K), which is related to the solubility of CBD in the vehicle. The PG:DEGEE binary vehicle boosted J_ss (1.5-1.6 fold) and deposition (2.0-2.7 folds) significantly, compared to neat DEGEE. The combination of DEGEE with MCT dramatically enhanced J_ss (11-44 fold) and deposition (1.6-4.7 fold). The addition of lipophilic enhancers, laurocapram, and oleic acid, to PG:DEGEE and DEGEE:MCT vehicles significantly reduced J_ss (0.3-0.7 fold) and deposition (0.4-0.8 fold) while nerolidol had no effect. These permeation reductions were found to be related to modification of the K and/or diffusivity values. This study provides useful basic information for the development of CBD formulations intended for transmucosal delivery.

Lipid-based solubilization technology via hot melt extrusion: promises and challenges

INTRODUCTION

Self-emulsifying drug delivery systems (SEDDS) are a promising strategy to improve the oral bioavailability of poorly water-soluble drugs (PWSD). The excipients of SEDDS enable permeation through the mucus and gastro-intestinal barrier, inhibiting efflux transporters (e.g. P-glycoprotein) of drugs. Poor drug loading capacity and formulation instability are the main setbacks of traditional SEDDS. The use of polymeric precipitation inhibitors was shown to create supersaturable SEDDS with increased drug payload, and their solidification can help to overcome the instability challenge. As an alternative to several existing SEDDS solidification technologies, hot melt extrusion (HME) holds the potential for lean and continuous manufacturing of supersaturable solid-SEDDS. Despite being ubiquitously applied in solid lipid and polymeric processing, HME has not yet been widely considered for the preparation of SEDDS.

AREAS COVERED

The review begins with the rationale why SEDDS as the preferred lipid-based delivery systems (LBDS) is suitable for the oral delivery of PWSD and discusses the common barriers to oral administration. The potential of LBDS to surmount them is discussed. SEDDS as the flagship of LBDS for PWSD is proposed with a special emphasis on solid-SEDDS. Finally, the opportunities and challenges of HME from the lipid-based excipient (LBE) processing and product performance standpoint are highlighted.

EXPERT OPINION

HME can be a continuous, solvent-free, cost-effective, and scalable technology for manufacturing solid supersaturable SEDDS. Several critical formulations and process parameters in successfully preparing SEDDS via HME are identified.

Mucoadhesive Nanocarriers as a Promising Strategy to Enhance Intracellular Delivery against Oral Cavity Carcinoma

Oral cancer, particularly squamous cell carcinoma (SCC), has posed a grave challenge to global health due to its high incidence, metastasis, and mortality rates. Despite numerous studies and favorable improvements in the therapeutic strategies over the past few decades, the prognosis of this disease remains dismal. Moreover, several drawbacks are associated with the conventional treatment; including permanent disfigurement and physical impairment that are attributed to surgical intervention, and systemic toxicity that results from aggressive radio- or chemotherapies, which impacts patients’ prognosis and post-treatment quality of life. The highly vascularized, non-keratinized oral mucosa appears as a potential route for cytotoxic drug administration in treating oral cancer. It acts as a non-invasive portal for drug entry targeting the local oral lesions of the early stages of cancer and the systemic metastasis sites of advanced cancer. The absorption of the poorly aqueous-soluble anti-cancer drugs can be enhanced due to the increased permeability of the ulcerous mucosa lining in the disease state and by bypassing the hepatic first-pass metabolism. However, some challenges in oral transmucosal drug delivery include the drugs’ taste, the limited surface area of the membrane lining the oral cavity, and flushing and enzymatic degradation by saliva. Therefore, mucoadhesive nanocarriers have emerged as promising platforms for controlled, targeted drug delivery in the oral cavity. The surface functionalization of nanocarriers with various moieties allows for drug targeting, bioavailability enhancement, and biodistribution at the site of action, while the mucoadhesive feature prolongs the drug’s residence time for preferential accumulation to optimize the therapeutic effect and reduce systemic toxicity. This review has been focused to highlight the potential of various nanocarriers (e.g., nanoparticles, nanoemulsions, nanocapsules, and liposomes) in conferring targeting, solubility and bioavailability enhancement of actives and mucoadhesive properties as novel tumor-targeted drug delivery approaches in oral cancer treatment.

Colloidal dynamics of emulsion droplets in mouth

The interaction of emulsions with the tongue is key to the sensory appeal of food and can potentially be exploited for oral/buccal pharmaceutical delivery. Whilst there is good understanding of the different mucoadhesive forces governing emulsion interaction with the tongue, their relative importance is not well understood. In addition, the physical location of emulsions within the saliva papillae on the tongue is not understood at all. A combination of ex vivo salivary film, and in vivo oral coating experiments were used to determine the importance of different mucoadhesive forces. Mucoadhesion of cationic emulsions was largely driven by electrostatic complexation. SDS-PAGE of the in vivo saliva coating highlighted that mucins were largely responsible for cationic emulsion mucoadhesion. Anionic emulsions were bound via hydrophobic/steric interactions to small salivary proteins typically located away from the mucin anchor points. The physical location and clustering of emulsions relative to the salivary film/papillae was probed via the invention of a fluorescent oral microscope. Cationic emulsions were densely clustered close to the papillae whilst anionic emulsions were suspended in the salivary film above the papillae. Interestingly, non-ionic emulsions were also trapped within the salivary film above the papillae as individual droplets. These findings highlight that whilst electrostatic complexation with saliva is a powerful mucoadhesive force, hydrophobic and steric interactions also act to induce oral retention of emulsions. The differences in physical location and clustering of emulsions within the salivary film hint at the 3D locations of the different salivary proteins driving each mucoadhesive interaction. This novel understanding of emulsion saliva/papillae interactions has potential to aid efficacy of buccal pharmaceutical delivery and the reduction of astringency in plant-based foods.

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.

Improvement of Resveratrol Permeation through Sublingual Mucosa: Chemical Permeation Enhancers versus Spray Drying Technique to Obtain Fast-Disintegrating Sublingual Mini-Tablets

Resveratrol (RSV) is a natural polyphenol with several interesting broad-spectrum pharmacological properties. However, it is characterized by poor oral bioavailability, extensive first-pass effect metabolism and low stability. Indeed, RSV could benefit from the advantage of the sublingual route of administration. In this view, RSV attitudes to crossing the porcine sublingual mucosa were evaluated and promoted both by six different chemical permeation enhancers (CPEs) as well as by preparing four innovative fast-disintegrating sublingual mini-tablets by spray drying followed by direct compression. Since RSV by itself exhibits a low permeation aptitude, this could be significantly enhanced by the use of CPEs as well as by embedding RSV in a spray-dried powder to be compressed in order to prepare fast-disintegrating mini-tablets. The most promising observed CPEs (menthol, lysine and urea) were then inserted into the most promising spray-dried excipients’ compositions (RSV-B and RSV-C), thus preparing CPE-loaded mini-tablets. However, this procedure leads to unsatisfactory results which preclude the possibility of merging the two proposed approaches. Finally, the best spray-dried composition (RSV-B) was further evaluated by SEM, FTIR, XRD and disintegration as well as dissolution behavior to prove its effectiveness as a sublingual fast-disintegrating formulation.

Mucoadhesion and Mucopenetration of Cannabidiol (CBD)-Loaded Mesoporous Carrier Systems for Buccal Drug Delivery

Transmucosal drug delivery represents a promising noninvasive option when drugs are employed which have a low oral bioavailability like CBD. However, this concept can only be successful as long as the formulation provides sufficient buccal retention and mucosal penetration. In this study, mucoadhesive carrier systems were evaluated consisting of CBD-loaded silica (Aeroperl 300) carriers, mucoadhesive polymers (Hypromellose (HPMC), chitosan and carbomer) and propylene glycol as a penetration enhancer. Mucoadhesive effect, drug release and penetration ability were evaluated for each carrier system. The results show that the addition of HPMC and carbomer substantially improve mucoadhesion compared to pure CBD, with an increase of 16-fold and 20-fold, respectively. However, due to their strong swelling, HPMC and carbomer hinder the penetration of CBD and rely on co-administration of propylene glycol as an enhancer to achieve sufficient mucosal absorption. Chitosan, on the other hand, achieves an 8-fold increase in mucoadhesion and enhances the amount of CBD absorbed by three times compared to pure CBD. Thus, chitosan represents a promising polymer to combine both effects. Considering the results, the development of silica-based buccal drug delivery systems is a promising approach for the effective delivery of CBD.

Screening of Surfactants for Improved Delivery of Antimicrobials and Poly-Lactic-co-Glycolic Acid Particles in Wound Tissue

Topical wound management is often a challenge due to the poor penetration of antimicrobials in wound tissue and across the biofilm matrix where bacteria are embedded. Surfactants have been used for decades to improve the stability of formulations, increase drug solubility, and enhance penetration. In this study, we screened different detergents with respect to their cytotoxicity and their ability to improve the penetration of poly-lactic-co-glycolic acid (PLGA) particles in wound tissue. Among the tested surfactants, Kolliphor SLS and Tween 80 increased the penetration of PLGA particles and had a limited cytotoxicity. Then, these surfactants were used to formulate PLGA particles loaded with the poorly water-soluble antibiotic ciprofloxacin. The antimicrobial efficacy of the formulations was tested in a wound infection model based on human ex vivo skin. We found that even though PLGA particles had the same antimicrobial efficiency than the particle-free drug formulation, thanks to their solubilizing and anti-biofilm properties, the surfactants remarkably improved the antimicrobial activity of ciprofloxacin with respect to the drug formulation in water. We conclude that the use of Tween 80 in antimicrobial formulations might be a safe and efficient option to improve the topical antimicrobial management of chronic wound infections.

Characterization of Insulin Mucoadhesive Buccal Films: Spectroscopic Analysis and In Vivo Evaluation

Insulin mucoadhesive buccal films (MBF) are a noninvasive insulin delivery system that offers an advantageous alternative route of administration to subcutaneous injection. One major concern in the formulation of insulin MBF is the preservation of an insulin secondary structure in the presence of the other film components. Buccal films were formulated using chitosan, glycerin, and L-arginine. The MBF-forming solutions (MBF-FS) and the films (MBF) were examined for their chemical and structural stability and for their in vivo activity. Enzyme-Linked Immunosorbent Assay (ELISA) of the insulin-loaded MBF showed that each individualized unit dose was at least loaded with 80% of the insulin theoretical dose. Results of Synchrotron Radiation Circular Dichroism (SRCD) measurements revealed that MBF-FS retained the α-helices and β–sheets conformations of insulin. Fourier transform infrared (FTIR)-microspectroscopy (FTIR-MS) examination of insulin MBF revealed the protective action of L-arginine on insulin structure by interacting with chitosan and minimizing the formation of an unordered structure and β-strand. A blood glucose-lowering effect of insulin MBF was observed in comparison with subcutaneous (S.C) injection using a rat model. As a result; chitosan-based MBFs were formulated and characterized using SRCD and FTIR-MS techniques. Furthermore, the results of in vivo testing suggested the MBFs as a promising delivery system for insulin.

Prolonged Delivery of Apomorphine Through the Buccal Mucosa, Towards a Noninvasive Sustained Administration Method in Parkinson's Disease: In Vivo Investigations in Pigs

In the current work, prolonged systemic delivery of apomorphine via buccal mucosa was shown to be a promising treatment for Parkinson's disease as a substitute for clinically utilized subcutaneous infusions. Due to extensive 'first-pass' metabolism, apomorphine is administered parenterally to bypass liver metabolism. Drawbacks of parenteral administration cause low patient compliance and adherence to treatment. On the other hand, while also bypassing the liver, delivery through buccal mucosa has a superior safety profile, is less costly, lacks pain and discomfort, and possesses excellent accessibility, overall augmenting patient compliance. Current in vivo study in pigs showed: (1) steady plateau levels of apomorphine in plasma were obtained 30 min following administration and remained constant for 8 h until a delivery device was removed, (2) bioavailability of apomorphine was 55%-80% as opposed to <2% peroral and (3) simulation of the pharmacokinetic profile obtained in pigs predicted therapeutically relevant levels of apomorphine in human. Furthermore, antipyrine was incorporated as a permeation marker to enable mechanistic investigation of apomorphine release from the delivery device and its permeation through the buccal mucosa. In addition, limitations of an Ussing diffusion chamber as an ex vivo research tool were also discussed.

Transbuccal Delivery of Isoniazid: Ex Vivo Permeability and Drug-Surfactant Interaction Studies

The oral administration of isoniazid (INH) may lead to discontinuation of tuberculosis treatment due to drug-related hepatotoxicity events, and thus, the transbuccal delivery of this drug was investigated, for the first time, as an alternative administration route. Ex vivo permeability assays were performed in Franz-type diffusion chambers, applying INH alone and in combination with sodium dodecyl sulfate (SDS) and sodium taurocholate (ST). After confirming the formation of micelle structures by dynamic light scattering analysis, UV-visible spectroscopy and zeta potential analyses were used to investigate drug-micelle interactions. In zeta potential analyses, no electrostatical interactions were identified for both surfactants in saliva buffer pH 6.8. Spectrophotometric analyses, in turn, indicated chemical interactions between INH and SDS in both pH values (2.0 and 6.8) whereas no interaction between the drug and ST was observed. Despite the interaction between SDS and drug, this surfactant increased the buccal transport rate of INH by approximately 11 times when compared with the control. In contrast, ST did not increase the drug permeability. The INH retention in SDS-treated mucosa was significantly higher when compared with the control and an effect on intercellular lipids was suggested. In vivo studies are needed to confirm the high INH absorption found here. Grapical abstract.

Estradiol softgel inserts for the treatment of VVA symptoms: an expert opinion

INTRODUCTION

Vulvar and vaginal atrophy (VVA) affects up to two thirds of postmenopausal women, with symptoms of vaginal dryness, dyspareunia, and vulvar/vaginal irritation. Despite the availability of various treatments, women express dissatisfaction with their options. An estradiol (E2; 4-µg and 10-µg) softgel vaginal insert was approved by the Food and Drug Administration (FDA) to treat moderate to severe dyspareunia, a symptom of VVA, due to menopause. These inserts were designed to treat VVA effectively and safely while avoiding some of the drawbacks of other administration methods.

AREAS COVERED

This article reviews the physical characteristics and pharmacokinetic data of the E2 softgel vaginal insert. Primary and secondary efficacy endpoints and safety data are reviewed from the pivotal REJOICE trial (NCT02253173), and substudies that explore response rates, changes in vaginal epithelium by visual assessment, efficacy in patient subgroups, effects on sexual function, and patient satisfaction compared with other treatments.

EXPERT OPINION

The E2 insert shows that vaginal drug delivery is an optimal route of administration for locally treating VVA. This E2 softgel vaginal insert is a safe and effective treatment for symptoms of postmenopausal VVA. The E2 insert's pharmacokinetic characteristics are related to its unique formulation, rapid dissolution, and minimal systemic absorption.

ABBREVIATIONS

AE: adverse event; AUC: area under the concentration-time curve; BMI: body mass index; C_avg: average concentration; CI: confidence interval; C_max: maximum concentration; C_min: minimum concentration; E2: estradiol; FDA: Food and Drug Administration; FSFI: Female Sexual Function Index; GSM: genitourinary symptoms of menopause: MBS: most bothersome symptom; NAMS: North American Menopause Society; OR: odds ratio; PI: pulsatility index; PK: pharmacokinetic; REVIVE: Real Women's Views of treatment options for menopausal Vaginal changEs; RI: resistance index; ROC: receiver operating characteristic; TEAE: treatment-emergent adverse event; t_max: time to maximum concentration; VVA: vulvar and vaginal atrophy.

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.

Progress in Drug and Formulation Development for the Chemoprevention of Oral Squamous Cell Carcinoma: A Review

BACKGROUND

Cancer is a life-threatening global problem with high incidence rates. Prioritizing the prevention of cancer, chemopreventive agents have drawn much attention from the researchers.

OBJECTIVE

This review focuses on the discussion of the progress in the development of chemopreventive agents and formulations related to the prevention of oral cancer.

METHODS

In this perspective, an extensive literature survey was carried out to understand the mechanism, control and chemoprevention of oral cancer. Different patented agents and formulations have also exhibited cancer preventive efficacy in experimental studies. This review summarizes the etiology of oral cancer and developments in prevention strategies.

RESULTS

The growth of oral cancer is a multistep activity necessitating the accumulation of genetic as well as epigenetic alterations in key regulatory genes. Many risk factors are associated with oral cancer. Genomic technique for sequencing all tumor specimens has been made available to help detect mutations. The recent development of molecular pathway and genetic tools has made the process of diagnosis easier, better forecast and efficient therapeutic management. Different chemical agents have been studied for their efficacy to prevent oral cancer and some of them have shown promising results.

CONCLUSION

Use of chemopreventive agents, either synthetic or natural origin, to prevent carcinogenesis is a worthy concept in the management of cancers. Preventive measures are helpful in controlling the occurrence or severity of the disease. The demonstrated results of preventive agents have opened an arena for the development of promising chemopreventive agents in the management of oral squamous cell carcinoma.

Mucoadhesive buccal film of almotriptan improved therapeutic delivery in rabbit model

Administration of almotriptan as an oral therapy is largely limited because of poor aqueous solubility and rather low bioavailability. The aim of present investigation was to formulate oral mucoadhesive film of almotriptan to improve the drug delivery and desired therapeutic effects. Placebo films (F1-F8) were prepared by varying the concentrations of Proloc 15 (7.5-15% w/v) and Eudragit RL 100/RS 100 (15-30% w/v) polymers. Physicomechanical and pharmaceutical characteristics of drug loaded films (FA1-FA4) were examined. Selected FA4 film was evaluated in vivo by assessing the pharmacokinetic profile and compared with oral therapy in rabbits. FA1-FA4 films exhibited excellent physicomechanical properties and rapid hydration. A biphasic and considerably greater drug release (p < 0.05) was observed in FA3 and FA4 films contain higher amount of hydrophilic polymer. The rate of permeation of almotriptan was found to be significantly higher in FA4 than FA3 film (p < 0.005). Fourier transform infrared spectral scan indicates no incompatibility exists between the drug and polymers used. Differential scanning calorimetry thermogram represents the evidence of almotriptan amorphization and molecular dispersion of it in the film. Scanning electron microscopy images shows that FA4 possess good morphological features and hence suitable for use in the buccal application. In vivo data demonstrated rapid and efficient absorption (p < 0.005) of almotriptan with greater AUC_0-12 (>2 folds, p < 0.0001) by FA4 film as compared to oral (control). In general, the data established the potential of FA4 film to improve the therapeutic delivery of almotriptan and offers a promising option in migraine therapy.

In vivo, ex vivo and in vitro assessment of buccal permeation of drugs from delivery systems

Introduction: Buccal mucosa has been described as an attractive site for local and systemic drug delivery, owing its accessibility, safety, and excellent blood supply. The absorption of drugs through buccal mucosa has been assessed by in vivo, ex vivo and in vitro permeability studies, using animal and cell-based models with close resemblance to the human buccal mucosa.Areas covered: This paper focuses on the current in vivo, ex vivo and in vitro permeability studies to analyze the absorption of compounds of interest through buccal mucosa, as well as their advantages and limitations in the preclinical studies of the drugs absorption profiles. The techniques for preparation and preservation of the animal buccal tissue are also discussed to evaluate their interference in the integrity and permeability of the tissues.Expert opinion: Overall, the permeability studies have been useful to evaluate the drugs absorption and to clarify the mechanism of transport of drugs across human buccal mucosa, as well as to explain the enhancement of permeability provided by certain dosage forms. Currently, several researchers have demonstrated particular interest in ex vivo permeability studies, due to their effectiveness in the evaluation of drug absorption and low costs in the acquisition of buccal mucosa samples.

Advances in Nanoparticulate Drug Delivery Approaches for Sublingual and Buccal Administration

The sublingual and buccal routes of administration have significant advantages for both local and systemic drug delivery. They have shown to be an effective alternative to the traditional oral route, especially when fast onset of action is required. Drugs can be rapidly and directly absorbed into the systemic circulation via venous drainage to the superior vena cava. Therefore, they are useful for drugs that undergo high hepatic clearance or degradation in the gastrointestinal tract, and for patients that have swallowing difficulties. Drugs administered via the sublingual and buccal routes are traditionally formulated as solid dosage forms (e.g., tablets, wafers, films, and patches), liquid dosage forms (e.g., sprays and drops), and semi-solid dosage forms (e.g., gels). Conventional dosage forms are commonly affected by physiological factors, which can reduce the contact of the formulation with the mucosa and lead to unpredictable drug absorption. There have been a number of advances in formulation development to improve the retention and absorption of drugs in the buccal and sublingual regions. This review will focus on the physiological aspects that influence buccal and sublingual drug delivery and the advances in nanoparticulate drug delivery approaches for sublingual and buccal administration. The clinical development pipeline with formulations approved and in clinical trials will also be addressed.

New Insights on the Mechanism of Fatty Acids as Buccal Permeation Enhancers

Buccal mucosa has recently received much attention as a potential route for systemic delivery of drugs, including biologics and vaccines. The aim of this work was to gain insight into the mechanism of fatty acids as buccal permeation enhancers, by studying the effect of a series of medium and long chain fatty acids on the permeation of a model high molecular weight and hydrophilic molecule, fluorescein isothiocyanate labelled dextran (FD-4, m.w. 4 kDa) across porcine esophageal epithelium. A parabolic relationship between fatty acid lipophilicity and enhancement was obtained, regardless of the presence and number of double bonds. The relationship, which resembles the well-known relationship between permeability and lipophilicity of transdermal delivery, presents a maximum value in correspondence of C10 (logP approx. 4). This is probably the ideal lipophilicity for the fatty acid to interact with the lipid domains of the mucosa. When the same analysis was performed on skin data, the same trend was observed, although the maximum value was reached for C12 (logP approx. 5), in agreement with the higher lipophilicity of the skin. The results obtained in the present work represent a significant advancement in the understanding of the mechanisms of action of fatty acids as buccal penetration enhancers.

Buccal delivery of small molecules - Impact of levulinic acid, oleic acid, sodium dodecyl sulfate and hypotonicity on ex vivo permeability and spatial distribution in mucosa

Studies of drug permeability rate and localization in buccal mucosa are essential to gain new knowledge of means such as chemical enhancers or osmolality to enhance buccal drug transport in the development of new buccal drug products. The transport of caffeine, diazepam and mannitol across porcine buccal mucosa was studied in modified Ussing chambers with a hypotonic donor solution, in the presence of levulinic acid (LA), oleic acid (OA), propylene glycol (PG) as well as sodium dodecyl sulfate (SDS). Subsequently, matrix-assisted laser desorption ionization - mass spectrometry imaging (MALDI-MSI) was applied to image the spatial distribution of caffeine, mannitol and SDS in cross-sections of porcine buccal mucosa. The results revealed that none of the permeation enhancing strategies improved the permeability of caffeine or diazepam, despite impact on the tissue integrity by OA and SDS, as seen by an increased permeability of mannitol. Further studies are needed with OA since PG solvent may have concealed the possible impact of OA. SDS decreased the permeability of caffeine and diazepam, a decrease which can be explained by micellar lipid extraction and encapsulation in micelles. MALDI-MSI showed that SDS permeated into approximately one-third of the epithelium, and it therefore appears that the main permeability barrier for mannitol is located in the outer epithelium. MALDI-MSI was shown to be a useful method for imaging spatial distribution of drugs and permeations enhancers in buccal mucosa.

Cell culture models of oral mucosal barriers: A review with a focus on applications, culture conditions and barrier properties

Understanding the function of oral mucosal epithelial barriers is essential for a plethora of research fields such as tumor biology, inflammation and infection diseases, microbiomics, pharmacology, drug delivery, dental and biomarker research. The barrier properties are comprised by a physical, a transport and a metabolic barrier, and all these barrier components play pivotal roles in the communication between saliva and blood. The sum of all epithelia of the oral cavity and salivary glands is defined as the blood-saliva barrier. The functionality of the barrier is regulated by its microenvironment and often altered during diseases. A huge array of cell culture models have been developed to mimic specific parts of the blood-saliva barrier, but no ultimate standard in vitro models have been established. This review provides a comprehensive overview about developed in vitro models of oral mucosal barriers, their applications, various cultivation protocols and corresponding barrier properties.

Challenges in the local delivery of peptides and proteins for oral mucositis management

Oral mucositis, a common inflammatory side effect of oncological treatments, is a disorder of the oral mucosa that can cause painful ulcerations, local motor disabilities, and an increased risk of infections. Due to the discomfort it produces and the associated health risks, it can lead to cancer treatment restrains, such as the need for dose reduction, cycle delays or abandonment. Current mucositis management has low efficiency in prevention and treatment. A topical drug application for a local action can be a more effective approach than systemic routes when addressing oral cavity pathologies. Local delivery of growth factors, antibodies, and anti-inflammatory cytokines have shown promising results. However, due to the peptide and protein nature of these novel agents, and the several anatomic, physiological and environmental challenges of the oral cavity, their local action might be limited when using traditional delivering systems. This review is an awareness of the issues and strategies in the local delivery of macromolecules for the management of oral mucositis.

Effect of Permeation Enhancers on the Buccal Permeability of Nicotine: Ex vivo Transport Studies Complemented by MALDI MS Imaging

PURPOSE

The purpose of this study was to assess the effect of several chemical permeation enhancers on the buccal permeability of nicotine and to image the spatial distribution of nicotine in buccal mucosa with and without buccal permeation enhancers.

METHODS

The impact of sodium taurodeoxycholate (STDC), sodium dodecyl sulphate (SDS), dimethyl sulfoxide (DMSO) and Azone® on the permeability of [³H]-nicotine and [¹⁴C]-mannitol (a paracellular marker) across porcine buccal mucosa was studied ex vivo in modified Ussing chambers. The distribution of nicotine, mannitol and permeation enhancers was imaged using using matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI MSI).

RESULTS

Despite STDC significantly increasing permeability of [¹⁴C]-mannitol, no enhancing effect was seen on [³H]-nicotine permeability with any of the permeation enhancers. Rather, SDS and DMSO retarded nicotine permeability, likely due to nicotine being retained in the donor compartment. The permeability results were complemented by the spatial distribution of nicotine and mannitol determined with MALDI MSI.

CONCLUSIONS

The buccal permeability of nicotine was affected in an enhancer specific manner, suggesting that nicotine primarily diffuses via the transcellular pathway. MALDI MSI was shown to complement ex vivo permeability studies and to be a useful qualitative tool for visualizing drug and penetration enhancer distribution in buccal mucosa.

Mucin dispersions as a model for the oromucosal mucus layer in in vitro and ex vivo buccal permeability studies of small molecules

The mucus layer is believed to play a part in drug permeation across the oral mucosa. Human freeze-dried saliva (HFDS) and porcine gastric mucin (PGM) was evaluated as model for mucus layer per se or in conjunction with in vitro and ex vivo buccal permeability models. Four small molecules (nicotine, mannitol, propranolol, caffeine) showed decreased permeability across mucin dispersions, compared to controls, and a greater effect was seen with HFDS than with PGM. Permeability of propranolol and caffeine across filter-grown TR146 cells was decreased by the presence of mucin, whereas no effect was found on nicotine and mannitol. Incubation of porcine buccal mucosa with mucin dispersions for 24 h compromised the integrity of the tissue, whereas 30 min incubation did not affect tissue integrity. Tissue incubation with mucin dispersions did not decrease nicotine permeability. For the studied model drugs, it is concluded that mucin dispersions constitute a minor barrier for drug diffusion compared to the epithelium.

Food contact materials and gut health: Implications for toxicity assessment and relevance of high molecular weight migrants

Gut health is determined by an intact epithelial barrier and balanced gut microbiota, both involved in the regulation of immune responses in the gut. Disruption of this system contributes to the etiology of various non-communicable diseases, including intestinal, metabolic, and autoimmune disorders. Studies suggest that some direct food additives, but also some food contaminants, such as pesticide residues and substances migrating from food contact materials (FCMs), may adversely affect the gut barrier or gut microbiota. Here, we focus on gut-related effects of FCM-relevant substances (e.g. surfactants, N-ring containing substances, nanoparticles, and antimicrobials) and show that gut health is an underappreciated target in the toxicity assessment of FCMs. Understanding FCMs' impact on gut health requires more attention to ensure safety and prevent gut-related chronic diseases. Our review further points to the existence of large population subgroups with an increased intestinal permeability; this may lead to higher uptake of compounds of not only low (<1000 Da) but also high (>1000 Da) molecular weight. We discuss the potential toxicological relevance of high molecular weight compounds in the gut and suggest that the scientific justification for the application of a molecular weight-based cut-off in risk assessment of FCMs should be reevaluated.

Polymeric drug delivery systems for intraoral site-specific chemoprevention of oral cancer

Oral cancer is among the most prevalent cancers in the world. Moreover, it is one of the major health problems and causes of death in many regions of the world. The traditional treatment modalities include surgical removal, radiation therapy, systemic chemotherapy, or a combination of these methods. In recent decades, there has been significant interest in intraoral site-specific chemoprevention via local drug delivery using polymeric systems. Because of its easy accessibility and clear visibility, the oral mucosa is amenable for local drug delivery. A variety of polymeric systems-such as gels, tablets, films, patches, injectable systems (e.g., millicylindrical implants, microparticles, and in situ-forming depots), and nanosized carriers (e.g., polymeric nanoparticles, nanofibers, polymer-drug conjugates, polymeric micelles, nanoliposomes, nanoemulsions, and polymersomes)-have been developed and evaluated for the local delivery of natural and synthetic chemopreventive agents. The findings of in vitro, ex vivo, and in vivo studies and the positive outcome of clinical trials demonstrate that intraoral site-specific drug delivery is an attractive, highly effective and patient-friendly strategy for the management of oral cancer. Intraoral site-specific drug delivery provides unique therapeutic advantages when compared to systemic chemotherapy. Moreover, intraoral drug delivery systems are self-administrable and can be removed when needed, increasing patient compliance. This article covers important aspects and advances related to the design, development, and efficacy of polymeric systems for intraoral site-specific drug delivery. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1383-1413, 2018.

Development and characterization of mucoadhesive buccal gels containing lipid nanoparticles of ibuprofen

The lipid nanoparticles, namely Nanostructured Lipid Carriers (NLC), as drug delivery systems have been investigated for several years. One of the delivery routes for which these carriers can be applied is buccal administration. However, the liquid dispersions of lipid nanoparticles can be rapidly removed from oral cavity by saliva. Thus, the development of a system that allows increased retention time on the mucosa is necessary. For this reason, the development of mucoadhesive preparations for buccal administration of lipid nanoparticles becomes important. Hydrogels prepared with mucoadhesive polymers (Carbopol^® 980 and polycarbophil) constitute a promising option. The aim of this work was to develop mucoadhesive buccal hydrogels with NLC, using ibuprofen as a model drug. The obtained results showed that the developed NLC dispersions presented particles in the nanometric size range, with low polydispersity index values and efficient ability for the entrapment of the model drug. Moreover, the incorporation of NLC in hydrogels of mucoadhesive polymers resulted in preparations with desirable rheological features as well as texture (firmness and adhesiveness) and mucoadhesive properties, which could benefit the therapeutic efficacy, by increasing the residence time and easiness for topical application in the buccal mucosa. Additionally, the developed preparations exhibited sustained drug release as intended for these systems.

Oromucosal multilayer films for tailor-made, controlled drug delivery

INTRODUCTION

The oral mucosa has recently become increasingly important as an alternative administration route for tailor-made, controlled drug delivery. Oromucosal multilayer films, assigned to the monograph oromucosal preparations in the Ph.Eur. may be a promising dosage form to overcome the requirements related to this drug delivery site. Areas covered: We provide an overview of multilayer films as drug delivery tools, and discuss manufacturing processes and characterization methods. We focus on the suitability of characterization methods for particular requirements of multilayer films. A classification was performed covering indication areas and APIs incorporated in multilayer film systems for oromucosal use in order to provide a summary of data published in this field. Expert opinion: The shift in drug development to high molecular weight drugs will influence the field of pharmaceutical development and delivery technologies. For a high number of indication areas, such as hormonal disorders, cardiovascular diseases or local treatment of infections, the flexible layer design of oromucosal multilayer films provides a promising option for tailor-made, controlled delivery of APIs to or through defined surfaces in the oral cavity. However, there is a lack of discriminating or standardized testing methods to assess the quality of multilayer films in a reliable way.

Emerging delivery platforms for mucosal administration of biopharmaceuticals: a critical update on nasal, pulmonary and oral routes

INTRODUCTION

Protein and peptide-based drugs are preferred therapeutics due to their specificity but are mainly administered by injection. Alternative routes for peptide delivery are preferred because of their ease of administration and increased patient compliance. Areas covered: This review provides a critical overview of current strategies for non-invasive mucosal delivery routes of therapeutic proteins and peptides, with emphasis on their advantages and limitations. Selected new trends and interesting novel formulations in advanced preclinical and clinical development stages for the pulmonary, nasal and the oral route are discussed for the most relevant peptide and protein drugs in terms of their specific requirements and intended therapeutic applications. Expert opinion: Despite the low frequency of clinical breakthroughs with non-invasive routes, these remain an active research area not only due to their improved therapeutic potential, but also due to the attractive commercial outcomes they offer. Currently, a number of technologies are adopted, including combinations of penetration enhancers with protease inhibitors and/or nanotechnology-based products and a few candidates are anticipated to be approved in the near future.