Phospholipid deformable vesicles for buccal delivery of insulin

Mucoadhesive film for oral delivery of vaccines for protection of the respiratory tract

The delivery of vaccines plays a pivotal role in influencing the strength and longevity of the immune response and controlling reactogenicity. Mucosal immunization, as compared to parenteral vaccination, could offer greater protection against respiratory infections while being less invasive. While oral vaccination has been presumed less effective and believed to target mainly the gastrointestinal tract, trans-buccal delivery using mucoadhesive films (MAF) may allow targeted delivery to the mucosa. Here we present an effective strategy for mucosal delivery of several vaccine platforms incorporated in MAF, including DNA plasmids, viral vectors, and lipid nanoparticles incorporating mRNA (mRNA/LNP). The mRNA/LNP vaccine formulation targeting SARS-CoV-2 as a proof of concept remained stable within MAF consisting of slowly releasing water-soluble polymers and an impermeable backing layer, facilitating enhanced penetration into the oral mucosa. This formulation elicited antibody and cellular responses comparable to the intramuscular injection, but also induced the production of mucosal IgAs, highlighting its efficacy, particularly for use as a booster vaccine and the potential advantage for protection against respiratory infections. The MAF vaccine preparation demonstrates significant advantages, such as efficient delivery, stability, and simple noninvasive administration with the potential to alleviate vaccine hesitancy.

Review on novel targeted enzyme drug delivery systems: enzymosomes

The goal of this review is to present enzymosomes as an innovative means for site-specific drug delivery. Enzymosomes make use of an enzyme's special characteristics, such as its capacity to accelerate the reaction rate and bind to a particular substrate at a regulated rate. Enzymosomes are created when an enzyme forms a covalent linkage with a liposome or lipid vesicle surface. To construct enzymosomes with specialized activities, enzymes are linked using acylation, direct conjugation, physical adsorption, and encapsulation techniques. By reducing the negative side effects of earlier treatment techniques and exhibiting efficient medication release, these cutting-edge drug delivery systems improve long-term sickness treatments. They could be a good substitute for antiplatelet medication, gout treatment, and other traditional medicines. Recently developed supramolecular vesicular delivery systems called enzymosomes have the potential to improve drug targeting, physicochemical characteristics, and ultimately bioavailability in the pharmaceutical industry. Enzymosomes have advantages over narrow-therapeutic index pharmaceuticals as focusing on their site of action enhances both their pharmacodynamic and pharmacokinetic profiles. Additionally, it reduces changes in normal enzymatic activity, which enhances the half-life of an enzyme and accomplishes enzyme activity on specific locations.

Polymer-Based Nanostructures for Pancreatic Beta-Cell Imaging and Non-Invasive Treatment of Diabetes

Diabetes poses major economic, social, and public health challenges in all countries worldwide. Besides cardiovascular disease and microangiopathy, diabetes is a leading cause of foot ulcers and lower limb amputations. With the continued rise of diabetes prevalence, it is expected that the future burden of diabetes complications, early mortality, and disabilities will increase. The diabetes epidemic is partly caused by the current lack of clinical imaging diagnostic tools, the timely monitoring of insulin secretion and insulin-expressing cell mass (beta (β)-cells), and the lack of patients' adherence to treatment, because some drugs are not tolerated or invasively administrated. In addition to this, there is a lack of efficient topical treatment capable of stopping the progression of disabilities, in particular for treating foot ulcers. In this context, polymer-based nanostructures garnered significant interest due to their tunable physicochemical characteristics, rich diversity, and biocompatibility. This review article emphasizes the last advances and discusses the prospects in the use of polymeric materials as nanocarriers for β-cell imaging and non-invasive drug delivery of insulin and antidiabetic drugs in the management of blood glucose and foot ulcers.

Examination of Effective Buccal Absorption of Salmon Calcitonin Using Cell-Penetrating Peptide-Conjugated Liposomal Drug Delivery System

Introduction

The buccal route has been considered an attractive alternative delivery route for injectable formulations. Cell-penetrating peptides (CPPs) are gaining increased attention for their cellular uptake and tissue permeation effects. This study was aimed to evaluate the in vitro and ex vivo permeation-enhancing effect of penetratin-conjugated liposomes for salmon calcitonin (sCT) in TR146 human buccal cells and porcine buccal tissues.

Methods

Penetratin was conjugated to phospholipids through a maleimide-thiol reaction. Liposomes were prepared and sCT was encapsulated using a thin-film hydration method. Physical properties such as particle size, zeta potential, encapsulation efficiency, and morphological images via transmission electron microscopy were obtained. Cellular uptake studies were conducted using flow cytometry (FACS) and confocal laser scanning microscopy (CLSM). A cell permeation study was performed using a Transwell^® assay, and permeation through porcine buccal tissue was evaluated. The amount of sCT permeated was quantified using an ELISA kit and was optically observed using CLSM.

Results

The particle size of penetratin-conjugated liposomes was approximately 123.0 nm, their zeta potential was +29.6 mV, and their calcitonin encapsulation efficiency was 18.0%. In the cellular uptake study using FACS and CLSM, stronger fluorescence was observed in penetratin-conjugated liposomes compared with the solution containing free sCT and control liposomes. Likewise, the amount of sCT permeated from penetratin-conjugated liposomes was higher than that from the free sCT solution and control liposomes by 5.8-fold across TR146 cells and 91.5-fold across porcine buccal tissues.

Conclusion

Penetratin-conjugated liposomes are considered a good drug delivery strategy for sCT via the buccal route.

Recent Advancements and Patents on Buccal Drug Delivery Systems: A Comprehensive Review

The major requirement for a dosage form to be successful is its ability to penetrate the site of application and the bioavailability of the drug released from the dosage form. The buccal drug delivery is an influential route to deliver the drug into the body. Here, in this context, various novel approaches that include lipoidal carriers like ethosomes, transferosomes, niosomes etc. and electrospun nanofibers are discussed, with respect to buccal drug delivery. These carriers can be easily incorporated into buccal dosage forms like patches and gels that are responsible for increased permeation across the buccal epithelium. The in vivo methods of evaluation on animal models are conscribed here. The novel biocarriers of lipoidal and non-lipoidal nature can be utilized by loading the drug into them, which are helpful in preventing drug degradation and other drawbacks as compared to conventional formulations. The globally patented buccal formulations give us a wide context in literature about the patents filed and granted in the recent years. When it comes to patient compliance, age is an issue, which is also solved by the buccal route. The pediatric buccal formulations are researched for the customization to be delivered to children. Diseases like mouth ulcers, oral cancer, Parkinson's disease, aphthous stomatitis etc. have been successfully treated through the buccal route, which infers that the buccal drug delivery system is an effective and emerging area for formulation and development in the field of pharmaceutics.

Bioavailability enhancement of voriconazole using liposomal pastilles: Formulation and experimental design investigation

Oral mucosa offers several advantages in the delivery of therapeutic molecules. It avoids presystemic metabolism, Nanoencapsulation techniques might be applied to conquer physical, chemical challenges and enhance drug penetration, formulation performance, prolonging drug residence time, and improving sensorial feeling. The present investigation is aimed to formulate liposomal pastilles with high bioavailability. Voriconazole Liposomes (VL) were produced by utilizing varied ratios of soya lecithin (SL) and cholesterol (CH) by solvent Injection method. RSM is utilized to identify the optimized formulation, as this design provides a thorough understanding of a process and also has great utilization in originating the robustness of the product. The main impact and interaction terms of the formulation variables were assessed quantitatively utilizing a mathematical-statistical approach indicating that both independent variables have significant ('P' value < 0.05) effects on particle size ('P' value: 0.0142), percentage entrapment efficiency ('P' value: 0.0120), percentage drug release through the dialysis membrane ('P' value: 0.0105), percentage drug release through porcine buccal mucosa ('P' value: 0.0171) and percentage zone of inhibition ('P' value: 0.0305). Optimal liposomal encapsulated in noticed in 15:10 lecithin: cholesterol concentration (VLP-6). Higher Lecithin and Cholesterol quantity in the liposome formulations resulted in lower drug entrapment efficiency and drug release when compared with middle levels of lecithin and cholesterol content formulation. The pastilles were prepared from the optimized liposomal formulation with a modified method reported in British Pharmaceutical Codex, 1907. These liposomal pastilles were subjected to evaluation of physicochemical parameters, In vitro drug release studies, stability studies, and In vivo bioavailability studies in comparison with pure voriconazole pastilles (PVP). The statistical data analysis results indicated that there was a significant difference in T_max, K_a, t_{1/2 abs}, t_{1/2 elim,} AUC_0-24, AUC_0-∞, AUMC_0-24 and AUMC_0-∞, values among PVP and VLP-6. There was no significant difference in C_max, K_el, MRT_0-24 and MRT_0-∞values among pure voriconazole pastilles and optimized liposomal formulation.

Improved Bioavailability of Ebastine through Development of Transfersomal Oral Films

The main objective of this research work was the development and evaluation of transfersomes integrated oral films for the bioavailability enhancement of Ebastine (EBT) to treat allergic rhinitis. The flexible transfersomes, consisting of drug (EBT), lipid (Phosphatidylcholine) and edge activator (EA) Polyoxyethylene sorbitan monooleate or Sorbitan monolaurate, were prepared with the conventional thin film hydration method. The developed transfersomes were further integrated into oral films using the solvent casting method. Transfersomes were evaluated for their size distribution, surface charge, entrapment efficiency (EE%) and relative deformability, whereas the formulated oral films were characterized for weight, thickness, pH, folding endurance, tensile strength, % of elongation, degree of crystallinity, water content, content uniformity, in vitro drug release and ex vivo permeation, as well as in vivo pharmacokinetic and pharmacodynamics profile. The mean hydrodynamic diameter of transfersomes was detected to be 75.87 ± 0.55 nm with an average PDI and zeta potential of 0.089 ± 0.01 and 33.5 ± 0.39 mV, respectively. The highest deformability of transfersomes of 18.52 mg/s was observed in the VS-3 formulation. The average entrapment efficiency of the transfersomes was about 95.15 ± 1.4%. Transfersomal oral films were found smooth with an average weight, thickness and tensile strength of 174.72 ± 2.3 mg, 0.313 ± 0.03 mm and 36.4 ± 1.1 MPa, respectively. The folding endurance, pH and elongation were found 132 ± 1, 6.8 ± 0.2 and 10.03 ± 0.4%, respectively. The ex vivo permeability of EBT from formulation ETF-5 was found to be approximately 2.86 folds higher than the pure drug and 1.81 folds higher than plain film (i.e., without loaded transfersomes). The relative oral bioavailability of ETF-5 was 2.95- and 1.7-fold higher than that of EBT-suspension and plain film, respectively. In addition, ETF-5 suppressed the wheal and flare completely within 24 h. Based on the physicochemical considerations, as well as in vitro and in vivo characterizations, it is concluded that the highly flexible transfersomal oral films (TOFs) effectively improved the bioavailability and antihistamine activity of EBT.

The impact of chemical engineering and technological advances on managing diabetes: present and future concepts

Monitoring blood glucose levels for diabetic patients is critical to achieve tight glycaemic control. As none of the current antidiabetic treatments restore lost functional β-cell mass in diabetic patients, insulin injections and the use of insulin pumps are most widely used in the management of glycaemia. The use of advanced and intelligent chemical engineering, together with the incorporation of micro- and nanotechnological-based processes have lately revolutionized diabetic management. The start of this concept goes back to 1974 with the description of an electrode that repeatedly measures the level of blood glucose and triggers insulin release from an infusion pump to enter the blood stream from a small reservoir upon need. Next to the insulin pumps, other drug delivery routes, including nasal, transdermal and buccal, are currently investigated. These processes necessitate competences from chemists, engineers-alike and innovative views of pharmacologists and diabetologists. Engineered micro and nanostructures hold a unique potential when it comes to drug delivery applications required for the treatment of diabetic patients. As the technical aspects of chemistry, biology and informatics on medicine are expanding fast, time has come to step back and to evaluate the impact of technology-driven chemistry on diabetics and how the bridges from research laboratories to market products are established. In this review, the large variety of therapeutic approaches proposed in the last five years for diabetic patients are discussed in an applied context. A survey of the state of the art of closed-loop insulin delivery strategies in response to blood glucose level fluctuation is provided together with insights into the emerging key technologies for diagnosis and drug development. Chemical engineering strategies centered on preserving and regenerating functional pancreatic β-cell mass are evoked in addition as they represent a permanent solution for diabetic patients.

Development, Characterization, and Ex Vivo Assessment of Elastic Liposomes for Enhancing the Buccal Delivery of Insulin

Buccal drug delivery is a suitable alternative to invasive routes of drug administration. The buccal administration of insulin for the management of diabetes has received substantial attention worldwide. The main aim of this study was to develop and characterize elastic liposomes and assess their permeability across porcine buccal tissues. Sodium-cholate-incorporated elastic liposomes (SC-EL) and sodium-glycodeoxycholate-incorporated elastic liposomes (SGDC-EL) were prepared using the thin-film hydration method. The prepared liposomes were characterized and their ex vivo permeability attributes were investigated. The distribution of the SC-EL and SGDC-EL across porcine buccal tissues was evaluated using confocal laser scanning microscopy (CLSM). The SGDC-EL were the most superior nanocarriers since they significantly enhanced the permeation of insulin across porcine buccal tissues, displaying a 4.33-fold increase in the permeability coefficient compared with the insulin solution. Compared with the SC-EL, the SGDC-EL were better at facilitating insulin permeability, with a 3.70-fold increase in the permeability coefficient across porcine buccal tissue. These findings were further corroborated based on bioimaging analysis using CLSM. SGDC-ELs showed the greatest fluorescence intensity in buccal tissues, as evidenced by the greater shift of fluorescence intensity toward the inner buccal tissue over time. The fluorescence intensity ranked as follows: SGDC-EL > SC-EL > FITC–insulin solution. Conclusively, this study highlighted the potential nanocarriers for enhancing the buccal permeability of insulin.

Factors affecting the buccal delivery of deformable nanovesicles based on insulin-phospholipid complex: an in vivo investigation

Deformable nanovesicles (DNVs) have been used in the buccal delivery of biomacromolecules due to their ability to enhance drug penetration. However, no breakthroughs have been made until now due to limited understanding of the factors affecting in vivo buccal delivery. In this study, we designed a series of DNVs, based on an insulin-phospholipid complex (IPC-DNVs), to investigate the influence of drug dose, buccal administration methods, and key quality characteristics of IPC-DNVs for buccal delivery. IPC-DNVs showed a non-linear dose-response relationship between 8 and 12 IU. There was no significant effect of drug delivery site (sublingual mucosa/buccal mucosa) or ligation time (15 or 30 min) on buccal absorption of IPC-DNVs. However, the area above the curve of reduction in blood glucose level overtime (AAC0-6h) for oral mucosa administration was significantly higher than that for buccal mucosa administration. Increasing the drug concentration in IPC-DNVs led to a decrease in AAC0-6h. This might be due to local leakage of DNVs, while squeezing through biological barriers with high concentration of insulin, thus hindering the subsequent delivery of DNVs. IPC-DNVs, measuring 80-220 nm in size, did not significantly affect AAC0-6h. However, when the size was increased to approximately 400 nm, AAC0-6h decreased, thus suggesting that IPC-DNVs with reasonable size were more effective. Additionally, increased deformability of IPC-DNVs might cause drugs to leak easily, thus reducing the promoting effect of buccal absorption. Our results clarified the effect of characteristics of IPC-DNVs on buccal delivery in vivo and provided meaningful support for the design of dosage form of DNVs.

Cell-penetrating peptide enhanced insulin buccal absorption

Non-injectable delivery of peptides and proteins is not feasible due to the limitations of large molecular mass, high hydrophilic properties, and gastrointestinal degradation. Therefore, proposing a new method to solve this problem is a burning issue. The objective of this study was to propose a novel protein delivery strategy to overcome the poor efficacy and irritation of buccal insulin delivery. In this study, we applied a conjugate of cell-penetrating peptides (LMWP) and insulin (INS-PEG-LMWP) for buccal delivery. INS-PEG-LMWP was prepared using insulin solution and mixture as references. The transport behaviour, in vivo bioactivity, hypoglycaemic effect, and safety of INS-PEG-LMWP were systematically characterised. An in vitro study demonstrated that the uptake and transportation of INS-PEG-LMWP across buccal mucosal multilayers significantly increased. By comparing the effects of different endocytic inhibitors on INS-PEG-LMWP uptake, the conjugate might be delivered via an energy independent, electrostatically adsorbed pathway. INS-PEG-LMWP's relative pharmacological bioavailability was high and its relative bioavailability was up to 26.86%, demonstrating no visible mucosal irritation. Cell-penetrating peptides are likely to become a reliable and safe tool for overcoming insulin's low permeability through the epithelial multilayers, the major barrier to buccal delivery.

Polymer-Based Nanoparticle Strategies for Insulin Delivery

Diabetes mellitus (DM) is a chronic metabolic illness estimated to have affected 451 million individuals to date, with this number expected to significantly rise in the coming years. There are two main classes of this disease, namely type 1 diabetes (T1D) and type 2 diabetes (T2D). Insulin therapy is pivotal in the management of diabetes, with diabetic individuals taking multiple daily insulin injections. However, the mode of administration has numerous drawbacks, resulting in poor patient compliance. In order to optimize insulin therapy, novel drug delivery systems (DDSes) have been suggested, and alternative routes of administration have been investigated. A novel aspect in the field of drug delivery was brought about by the coalescence of polymeric science and nanotechnology. In addition to polymeric nanoparticles (PNPs), insulin DDSes can incorporate the use of nanoplatforms/carriers. A combination of these systems can bring about novel formulations and lead to significant improvements in the drug delivery system (DDS) with regard to therapeutic efficacy, bioavailability, increased half-life, improved transport through physical and chemical barriers, and controlled drug delivery. This review will discuss how recent developments in polymer chemistry and nanotechnology have been employed in a multitude of platforms as well as in administration routes for the safe and efficient delivery of insulin for the treatment of DM.

Facilitated permeation of insulin across TR146 cells by cholic acid derivatives-modified elastic bilosomes

BACKGROUND

Buccal delivery of insulin is still a challenging issue for the researchers due to the presence of permeability barrier (buccal mucosa) in the buccal cavity. The main objective of this study was to investigate the safety, effectiveness, and potential of various liposomes containing different bile salts to improve the permeation of insulin across in vitro TR146 buccal cell layers.

METHODS

Elastic bilosomes containing soy lecithin and bile salt edge activators (sodium cholate [SC], sodium taurocholate [STC], sodium glycocholate [SGC], sodium deoxyglycocholate [SDGC], or sodium deoxytaurocholate [SDTC]) were fabricated by thin-film hydration method. The prepared liposomes were characterized, and in vitro permeation studies were performed. The fluorescein isothiocyanate-insulin-loaded elastic bilosomes were used to evaluate the quantitative and qualitative cellular uptake studies.

RESULTS

The prepared elastic bilosomes had a particle size and an entrapment efficiency of ~140-150 nm and 66%-78%, respectively. SDGC-lipo (SDGC-incorporated liposome) was observed to be the most superior with an enhancement ratio (ER) of 5.24 (P<0.001). The SC-incorporated liposome (SC-lipo) and SDTC-incorporated liposome (SDTC-lipo) also led to a significant enhancement with ERs of 3.20 and 3.10 (P<0.05), respectively, compared with insulin solution. These results were further supported by quantitative and qualitative cellular uptake studies performed employing fluorescence-activated cell sorting analysis and confocal microscopy, respectively. The relative median fluorescence intensity values of elastic bilosomes were counted in the order of SDGC-lipo > SC-lipo > SDTC-lipo > SGC-incorporated liposome > STC-incorporated liposome, and similarity in the permeability profile of the employed elastic bilosomes was noted.

CONCLUSION

This study presents the employment of various derivatives of cholic acid-loaded elastic bilosomes as a promising strategy to enhance the permeation of insulin through buccal route.

A practical framework for implementing Quality by Design to the development of topical drug products: Nanosystem-based dosage forms

Skin has been increasingly recognized as an important drug administration route with topical formulations, offering a targeted approach for the treatment of several dermatological disorders. The effectiveness of this route is hampered by its natural barrier, the stratum corneum (SC), and hence, different strategies have been investigated to improve percutaneous drug transport. The design of nanodelivery systems, aiming at solving skin delivery issues, have been largely explored, due to their potential to revolutionize dermal therapies, improving therapeutic effectiveness and reducing side effects. Apart from nanosystem benefits, the fulfilment of the reproducibility requirements and quality standards still limit their industrial production. The optimization of nanosystem formulation and manufacturing process is complex, usually involving a large number of variables. Therefore, a science- and risk-oriented approach, such as Quality by Design (QbD) will provide a comprehensive and noteworthy knowledge, yielding high quality drug products without extensive regulatory burden. This review aims to set up the basis for QbD development approach, encompassing preliminary and systematic risk assessments, with critical process parameters (CPPs) and critical material attributes (CMAs) identification, of different nanosystems potentially used in dermal therapies.

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.

Recent insights in the use of nanocarriers for the oral delivery of bioactive proteins and peptides

Bioactive proteins and peptides have been used with either prophylactic or therapeutic purposes, presenting inherent advantages as high specificity and biocompatibility. Nanocarriers play an important role in the stabilization of proteins and peptides, offering enhanced buccal permeation and protection while crossing the gastrointestinal tract. Moreover, preparation of nanoparticles as oral delivery systems for proteins/peptides may include tailored formulation along with functionalization aiming bioavailability enhancement of carried proteins or peptides. Oral delivery systems, namely buccal delivery systems, represent an interesting alternative route to parenteric delivery systems to carry proteins and peptides, resulting in higher comfort of administration and, therefore, compliance to treatment. This paper outlines an extensive overview of the existing publications on proteins/peptides oral nanocarriers delivery systems, with special focus on buccal route. Manufacturing aspects of most commonly used nanoparticles for oral delivery (e.g. polymeric nanoparticles using synthetic or natural polymers and lipid nanoparticles) advantages and limitations and potential applications of nanoparticles as proteins/peptides delivery systems will also be thoroughly addressed.

Enhancing the buccal mucosal delivery of peptide and protein therapeutics

With continuing advances in biotechnology and genetic engineering, there has been a dramatic increase in the availability of new biomacromolecules, such as peptides and proteins that have the potential to ameliorate the symptoms of many poorly-treated diseases. Although most of these macromolecular therapeutics exhibit high potency, their large molecular mass, susceptibility to enzymatic degradation, immunogenicity and tendency to undergo aggregation, adsorption, and denaturation have limited their ability to be administered via the traditional oral route. As a result, alternative noninvasive routes have been investigated for the systemic delivery of these macromolecules, one of which is the buccal mucosa. The buccal mucosa offers a number of advantages over the oral route, making it attractive for the delivery of peptides and proteins. However, the buccal mucosa still exhibits some permeability-limiting properties, and therefore various methods have been explored to enhance the delivery of macromolecules via this route, including the use of chemical penetration enhancers, physical methods, particulate systems and mucoadhesive formulations. The incorporation of anti-aggregating agents in buccal formulations also appears to show promise in other mucosal delivery systems, but has not yet been considered for buccal mucosal drug delivery. This review provides an update on recent approaches that have shown promise in enhancing the buccal mucosal transport of macromolecules, with a major focus on proteins and peptides.

Preparation of transfersomes encapsulating sildenafil aimed for transdermal drug delivery: Plackett-Burman design and characterization

The aim of this work was to study the effect of different processing and formulation parameters on the preparation of sildenafil (SD) transfersomes utilizing the Plackett-Burman design. The drug to phospholipid molar ratio (X1), phospholipid to surfactant ratio (X2), hydrophilic-lipophilic balance of the surfactant (X3), hydration medium pH (X4), hydration time (X5) and the temperature of hydration (X6) were investigated to study their effect on the vesicle size (Y1) and entrapment efficiency (EE) of the drug (Y2). The preparation conditions were optimized to minimize the vesicle size and maximize the EE. The prepared transfersomes were also subjected to zeta potential measurements, morphological and physicochemical characterization. The combinations of factors that achieve the optimum desirability were identified. An optimized formulation was prepared and characterized once more for its vesicle size, EE, in vitro permeation and deformability index. The results revealed that both X3 and X6 had a pronounced effect on Y1, while X1 and X4 showed a significant effect on Y2. Morphological and physicochemical study confirmed the transfersomes spherical shape and compatibility of the formulation ingredients. The formulation with optimum desirability showed EE and vesicle size of 97.21% and 610 nm, respectively. In vitro permeation of the drug-loaded transfersome showed more than 5-fold higher permeation rate compared with drug suspension. Deformability index verified elasticity of the preparation. The significant variables could be optimized again to produce smaller vesicle size that could increase SD permeation from transdermal delivery systems loaded drug optimized transfersomes.

Buccal drug delivery: A challenge already won?

The main obstacles that drugs meet when administered via the buccal route derive from the limited absorption area and the barrier properties of the mucosa. The effective physiological removal mechanisms of the oral cavity that take the formulation away from the absorption site are the other obstacles that have to be considered. The strategies studied to overcome such obstacles include the employment of new materials that, possibly, combine mucoadhesive, enzyme inhibitory and penetration enhancer properties and the design of innovative drug delivery systems which, besides improving patient compliance, favor a more intimate contact of the drug with the absorption mucosa.:

Nanovesicles system for rapid-onset sublingual delivery containing sodium tanshinone IIA sulfonate: in vitro and in vivo evaluation

A novel formulation based on nanovesicles system for rapid-onset sublingual delivery of hydrophilic drug (sodium tanshinone IIA sulfonate, STS) was investigated. The nanovesicles system was composed of 1.5% soybean lecithin, 6% propylene glycol, and penetration enhancers (1% sodium dodecyl sulfate and 0.03% hyaluronan acid). The STS-loaded nanovesicles with an average diameter of 133 ± 9.04 nm and high entrapment efficiency of 85.65 ± 3.89% were characterized. The effects of permeation enhancers on the penetration of STS formulations were investigated using Franz diffusion cells in vitro, showing 86.1-235.8 times higher permeation rate than that of normal STS solution. The rapid symptom relief effect of the nanovesicles system on acute myocardial infarction rabbits was evaluated by in vivo study, ST-segment deviation(S and T wave abnormality in electrocardiogram) was attenuated markedly and rapidly within 5 min, infarct size of heart was significantly reduced and the biochemical indicators were substantially decreased, compared with the control groups (p < 0.05). This study provided a promising tool for the future sublingual delivery of hydrophilic compounds with the noninvasive and rapid onset clinical effect.

Oral delivery of human biopharmaceuticals, autoantigens and vaccine antigens bioencapsulated in plant cells

Among 12billion injections administered annually, unsafe delivery leads to >20million infections and >100million reactions. In an emerging new concept, freeze-dried plant cells (lettuce) expressing vaccine antigens/biopharmaceuticals are protected in the stomach from acids/enzymes but are released to the immune or blood circulatory system when plant cell walls are digested by microbes that colonize the gut. Vaccine antigens bioencapsulated in plant cells upon oral delivery after priming, conferred both mucosal and systemic immunity and protection against bacterial, viral or protozoan pathogens or toxin challenge. Oral delivery of autoantigens was effective against complications of type 1 diabetes and hemophilia, by developing tolerance. Oral delivery of proinsulin or exendin-4 expressed in plant cells regulated blood glucose levels similar to injections. Therefore, this new platform offers a low cost alternative to deliver different therapeutic proteins to combat infectious or inherited diseases by eliminating inactivated pathogens, expensive purification, cold storage/transportation and sterile injections.

Ultra-adaptable nanovesicular systems: a carrier for systemic delivery of therapeutic agents

The skin acts as a barrier and prevents transcutaneous delivery of therapeutic agents. Transferosomes are novel vesicular systems that are several times more elastic than other vesicular systems. These are composed of phospholipids, edge activator and ethanol and are applied in a non-occlusive manner. Owing to their ultradeformability, they have the potential to deliver therapeutic agents across the intact skin in a non-invasive and non-allergenic manner. The present review attempts to provide an in-depth account of ultra-adaptable nanovesicular systems. The current investigation, besides compiling existing knowledge in a systematic manner, also includes information like regulatory aspects of excipients used in preparation, summary of clinical investigations performed, marketed preparations available, research reports and patent reports related to transfersomes.

Formulation, optimization and evaluation of transferosomal gel for transdermal insulin delivery

The present study deals with the development of transferosomal gel containing insulin by reverse phase evaporation method for painless insulin delivery for use in the treatment of insulin dependent diabetes mellitus. The effect of independent process variables like ratio of lipids (soya lecithin:cholesterol), ratio of lipids and surfactants, and ratio of surfactants (Tween 80:sodium deoxycholate) on the in vitro permeation flux (μg/cm(2)/h) of formulated transferosomal gels containing insulin through porcine ear skin was optimized using 2(3) factorial design. The optimal permeation flux was achieved as 13.50 ± 0.22 μg/cm(2)/h with drug entrapment efficiency of 56.55 ± 0.37% and average vesicle diameter range, 625-815 nm. The in vitro insulin permeation through porcine ear skin from these transferosomal gel followed zero-order kinetics (R (2) = 0.9232-0.9989) over a period of 24 h with case-II transport mechanism. The in vitro skin permeation of insulin from optimized transferosomal gel by iontophoretic influence (with 0.5 mA/cm(2) current supply) also provided further enhancement of permeation flux to 17.60 ± 0.03 μg/cm(2)/h. The in vivo study of optimized transferosomal gel in alloxan-induced diabetic rat has demonstrated prolonged hypoglycemic effect in diabetic rats over 24 h after transdermal administration.

Current challenges in non-invasive insulin delivery systems: a comparative review

The quest to eliminate the needle from insulin delivery and to replace it with non- or less-invasive alternative routes has driven rigorous pharmaceutical research to replace the injectable forms of insulin. Recently, various approaches have been studied involving many strategies using various technologies that have shown success in delivering insulin, which are designed to overcome the inherent barriers for insulin uptake across the gastrointestinal tract, mucosal membranes and skin. This review examines some of the many attempts made to develop alternative, more convenient routes for insulin delivery to avoid existing long-term dependence on multiple subcutaneous injections and to improve the pharmacodynamic properties of insulin. In addition, this article concentrates on the successes in this new millennium in developing potential non-invasive technologies and devices, and on major new milestones in modern insulin delivery for the effective treatment of diabetes.

Multivariate toxicity screening of liposomal formulations on a human buccal cell line

The influence of various formulation factors on the in vitro cellular toxicity of liposomes on human buccal cells (TR146), were studied by using the concept of statistical experimental design and multivariate evaluation. The factors investigated were the type of main phospholipid (egg-PC, DMPC, DPPC), lipid concentration, the type of charge, liposome size, and amount and nature of the charged component (diacyl-PA, diacyl-PG, diacyl-PS, stearylamine (SA), diacyl-TAP) in the liposomes. Both full factorial design and D-optimal designs were created. Several significant main factors and interactions were revealed. Positively charged liposomes were shown to be toxic. The toxicity of negatively charged liposomes was relatively low. Diacyl-TAP was less toxic than SA, and DPPC was less toxic than DMPC. Low level of positively charged component was favourable and essential when using egg-PC as the main lipid. The amount of negatively charged component, the liposome size, and the total lipid concentration did not affect the toxicity within the experimental room. DPPC appeared to be a good candidate when formulating both positively and negatively charged liposomes with low cellular toxicity. The concept of statistical experimental design and multivariate evaluation was shown to be a useful approach in cell toxicity screening studies.

Insulin loaded eudragit L100 microspheres for oral delivery: preliminary in vitro studies

Eudragit L100 microspheres were prepared using water-in-oil-in water (w/o/w) emulsion-solvent evaporation with polysorbate 20 as dispersing agent in the internal aqueous phase, and PVA/PVP as stabilizer in the external aqueous phase. Smaller internal and external aqueous phases provided higher drug encapsulation. The PVA-stabilized microspheres having maximum drug encapsulation (84.5 2.8%) released 7% insulin at pH 1.0 in 2 h. In phosphate buffer (pH 7.4), microspheres showed an initial burst release of 21% in 1 h with additional 35% release in the next 5 h. The smaller the volumes of internal and external aqueous phases, the lower the initial burst release. The release of drug from microspheres followed Higuchi kinetics. Scanning electron microscopy of PVA stabilized microspheres demonstrated spherical particles with smooth surface and laser diffractometry revealed a mean particle size (V(m)) of 59.11 30 m.

Eudragit S100 entrapped insulin microspheres for oral delivery

The purpose of this research was to investigate whether Eudragit S100 microspheres have the potential to serve as an oral carrier for peptide drugs like insulin. Microspheres were prepared using water-in oil-in water emulsion solvent evaporation technique with polysorbate 20 as a dispersing agent in the internal aqueous phase and polyvinyl alcohol (PVA)/polyvinyl pyrrolidone as a stabilizer in the external aqueous phase. The use of smaller internal aqueous-phase volume (50 microL) and external aqueous-phase volume (25 mL) containing PVA in the manufacturing process resulted in maximum encapsulation efficiency (81.8% +/- 0.9%). PVA-stabilized microspheres having maximum drug encapsulation released 2.5% insulin at pH 1.0 in 2 hours. In phosphate buffer (pH 7.4), microspheres showed an initial burst release of 22% in 1 hour with an additional 28% release in the next 5 hours. The smaller the volumes of internal and external aqueous phase, the lower the initial burst release. The release of drug from microspheres followed Higuchi kinetics. Scanning electron microscopy of PVA-stabilized microspheres demonstrated spherical particles with smooth surface, and laser diffractometry revealed a mean particle size of 32.51 +/- 20 microm. Oral administration of PVA stabilized microspheres in normal albino rabbits (equivalent to 6.6 IU insulin/kg of animal weight) demonstrated a 24% reduction in blood glucose level, with maximum plasma glucose reduction of 76 +/- 3.0% in 2 hours and effect continuing up to 6 hours. The area under the percentage glucose reduction-time curve was 93.75%. Thus, our results indicate that Eudragit S100 microspheres on oral administration can protect insulin from proteolytic degradation in the gastrointestinal tract and produce hypoglycemic effect.

Recent advances with liposomes as pharmaceutical carriers

Liposomes - microscopic phospholipid bubbles with a bilayered membrane structure - have received a lot of attention during the past 30 years as pharmaceutical carriers of great potential. More recently, many new developments have been seen in the area of liposomal drugs - from clinically approved products to new experimental applications, with gene delivery and cancer therapy still being the principal areas of interest. For further successful development of this field, promising trends must be identified and exploited, albeit with a clear understanding of the limitations of these approaches.

A new delivery system of clobetasol-17-propionate (lipid-loaded microspheres 0.025%) compared with a conventional formulation (lipophilic ointment in a hydrophilic phase 0.025%) in topical treatment of atrophic/erosive oral lichen planus. A Phase IV, randomized, observer-blinded, parallel group clinical trial

BACKGROUND

Topical application of clobetasol-17-propionate has been diffusely reported as an efficacious therapy in atrophic/erosive oral lichen planus (OLP), without exposing the patient to systemic side-effects. However, prolonged contact and respective topical effects on the oral mucosa should be avoided.

OBJECTIVES

The aim of the present study was to evaluate efficacy and compliance of new lipid microspheres loaded with 0.025% of clobetasol propionate (formulation A) compared with a commonly used formulation (a sort of dispersion of a lipophilic ointment in a hydrophilic phase) with the same amount of drug (formulation B) in the topical treatment of OLP.

PATIENTS AND METHODS

Fifty patients with symptomatic OLP were enrolled in a controlled single-blind phase IV clinical trial. After a dropout of five patients, a total of 45 patients [12 males and 33 females; mean age 61.1 years (+/- 12.3 SD; range 25-82)] were treated (17 with formulation A and 28 with formulation B, matched for gender and age; P > 0.2) with the same dosage regimen. At times T0, T1 and T2 we evaluated the following parameters: (i) pain score (by linear visual analogue scale; 0-100); (ii) clinical score; (iii) clinical resolution; and (iv) patient compliance. Statistical analysis was calculated using S-Plus 4.0 and SPSS 9.0 (Student's t-test, chi(2), Kolmogorov-Smirnow, Friedman, Student-Newman-Keuls, Mann-Whitney U-test and Spearman tests).

RESULTS

Both formulations were found to be similar for parameters ii, iii and iv, although with a better general trend for formulation A; a significant difference was registered for formulation A in terms of a reduction in painful symptoms (parameter i) at time T2 (P = 0.02).

CONCLUSIONS

Our results suggest that the new topical drug delivery system (formulation A) may enhance, at least in terms of symptom remission and compliance, the effectiveness of clobetasol propionate at a dose of 0.025% in OLP therapy.

Alternative routes of insulin delivery

Attempts at replicating physiological insulin secretion, as a means of restoring the normal metabolic milieu and thereby minimizing the risk of diabetic complications, has become an essential feature of insulin treatment. However, despite advances in the production, purification, formulation and methods of delivery of insulin which have occurred in recent years, this has met with limited success. The current advocacy of intensive insulin therapy regimens involving multiple daily subcutaneous injection places a heavy burden of compliance on patients and has prompted interest in developing alternative, less invasive routes of delivery. To date, attempts to exploit the nasal, oral, gastrointestinal and transdermal routes have been mainly unsuccessful. The respiratory tree, with a large surface area, offers the greatest potential for the delivery of polypeptide drugs and there is renewed interest in administrating insulin by the intrapulmonary route. Current pulmonary drug delivery systems include a variety of pressurized metered dose inhalers, dry powder inhalers, nebulizers and aqueous mist inhalers. Recent clinical studies suggest a possible role for inhaled insulin in fulfilling meal-related insulin requirements in persons with Type 1 and Type 2 diabetes. Most experience with inhaled insulin has been obtained using either dry powder formulation in the Nektar Pulmonary Inhaler/Exubera device (Nektar Therapeutics Inc., San Carlos, CA, Aventis, Bridgewater, NJ, Pfizer, NY) or a liquid aerosol formulation in the AERx Insulin Diabetes Management System (Aradigm Corp., Hayward, CA, NovoNordisk A/S, Copenhagen, Denmark). If long-term safety and efficacy is confirmed, inhalation may become the first non-subcutaneous route of insulin administration for widespread clinical use. Despite overwhelming interest and investment in administering insulin via the oral route, success is not expected in the short term. Attempts at utilizing the buccal mucosa and skin are also continuing. Pancreatic transplantation will remain limited to those patients receiving a kidney transplant and immunotherapy. Islet cell transplantation is at an early though encouraging stage following the availability of new less toxic immunosuppressive agents. True insulin independence will require further advances in the combined fields of cell biology and genetics to ensure freedom from both the need for lifelong administration of insulin and the complications of diabetes.