Mucoadhesive microspheres for gastroretentive delivery of acyclovir: in vitro and in vivo evaluation

Resorbable nanofibrous membranes for local and sustained co-delivery of acyclovir and ketorolac in herpes therapy

Herpes simplex and herpes zoster are both viral infections caused by members of the herpesvirus family. The former is characterized by painful, fluid-filled blisters or sores on the skin and mucous membranes, while the latter presents as a painful rash with blisters, typically occurring in a single band or patch along one side of the body. The treatment remains a challenge since current antiviral therapy via oral administration may lead to unfavorable side effects such as headaches, nausea, and diarrhea. This study used electrospinning to develop biodegradable nanofibrous poly(lactic-co-glycolic acid) (PLGA) membranes for delivery of both acyclovir and ketorolac. The structure of the spun nanofibers was assessed via scanning electron microscopy (SEM), and the appearance of loaded acyclovir and ketorolac in the nanofibers was confirmed with Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). Release profiles of these drugs from the nanofibrous membranes were assessed using in vitro elution studies, high-performance liquid chromatography (HPLC) assays, and in vivo drug release patterns. The electrospun nanofibers had a size range of 283-725 nm in diameter, resembling the extracellular matrix of natural tissue and demonstrated excellent flexibility and extensibility. Notably, the drug-eluting nanofibers exhibited an extended release of high levels of acyclovir and ketorolac over a 21-day period. Thus, biodegradable drug-eluting membranes with a prolonged drug release could be a potential therapeutic approach for treating herpes infections.

Mucoadhesive drug delivery systems: a promising non-invasive approach to bioavailability enhancement. Part I: biophysical considerations

INTRODUCTION

Mucoadhesive drug delivery systems (MDDS) are specifically designed to interact and bind to the mucosal layer for localized, prolonged, and/or targeted drug delivery. Over the past 4 decades, different sites have been explored for mucoadhesion including the nasal, oral, and vaginal cavities, the gastrointestinal tract and ocular tissues.

AREAS COVERED

The present review aims to provide a comprehensive understanding of different aspects of MDDS development. Part I focuses on the anatomical and biological aspects of mucoadhesion, which include a detailed elucidation of the structure and anatomy of the mucosa, the properties of mucin, the different theories of mucoadhesion and evaluation techniques.

EXPERT OPINION

The mucosal layer presents a unique opportunity for effective localization as well as systemic drug delivery via MDDS. Formulation of MDDS requires a thorough understanding of the anatomy of mucus tissue, the rate of mucus secretion and turnover, and the physicochemical properties of mucus. Further, the moisture content and the hydration of polymers are crucial for interaction with mucus. A confluence of different theories used to explain the mechanism of mucoadhesion is useful for understanding the mucoadhesion of different MDDS and their evaluation is subject to factors, such as the site of administration, type of dosage form, and duration of action. [Figure: see text].

Evaluation of Ulcer Protective Activity of Morus alba L. Extract-Loaded Chitosan Microspheres in Ethanol-Induced Ulcer in Rat Model

Due to an unhealthy lifestyle, gastric ulcers have become a very common disease these days. Moreover, the side effects linked with the prolonged use of conventional treatments have shifted the paradigm towards herbal therapies. The leaves of Morus alba L. (Family-Moraceae) have been traditionally used for a large number of metabolic diseases. In the present research, we focused on the development of chitosan microspheres using extracts of leaves of Morus alba L. and their evaluation for gastroprotective efficacy against ethanol-induced ulcers in experimental rats. The process of development of M. alba extract microsphere (MEM) is also optimized using the Box-Behnken design. The formulation was prepared at optimized conditions (chitosan concentration (1.66% w/w), volume of glutaraldehyde (4.69 mL), and stirrer rotation per minute, RPM, 854.8), and the percentage yield (Y ₁) of the resulted microspheres is ∼95% with an encapsulation efficiency (EE) of (Y _2(rutin)) ∼86%, Y _2(quercetin)) ∼85%, and particle size (Y ₃) of ∼40 µm. The MEM prepared at optimized conditions can also be characterized for various parameters to ensure the uniformity of parameters. Also, the drug release studies indicated that the percentage release of rutin and quercetin from MEM was enhanced as compared to M. alba extract (ME) alone. Furthermore, in vivo analysis of the antiulcer potential of pretreatment with ME and MEM (500 mg/kg p.o.) in rats indicated that mucosal lesions, gastric juice volume, and total acidity were significantly altered as compared to ethanol-treated animals. Histopathology of tissue sections also confirmed the protection of gastric mucosa on pretreatment with MEM at 500 mg/kg p.o. On the basis of these findings, we can conclude that prepared microspheres can be used to develop a sustained release formulation of extract for the management of gastric ulcers. However, additional research is needed to establish the specific mechanisms of M. alba's antiulcer efficacy.

Mucus interaction to improve gastrointestinal retention and pharmacokinetics of orally administered nano-drug delivery systems

Oral delivery of therapeutics is the preferred route of administration due to ease of administration which is associated with greater patient medication adherence. One major barrier to oral delivery and intestinal absorption is rapid clearance of the drug and the drug delivery system from the gastrointestinal (GI) tract. To address this issue, researchers have investigated using GI mucus to help maximize the pharmacokinetics of the therapeutic; while mucus can act as a barrier to effective oral delivery, it can also be used as an anchoring mechanism to improve intestinal residence. Nano-drug delivery systems that use materials which can interact with the mucus layers in the GI tract can enable longer residence time, improving the efficacy of oral drug delivery. This review examines the properties and function of mucus in the GI tract, as well as diseases that alter mucus. Three broad classes of mucus-interacting systems are discussed: mucoadhesive, mucus-penetrating, and mucolytic drug delivery systems. For each class of system, the basis for mucus interaction is presented, and examples of materials that inform the development of these systems are discussed and reviewed. Finally, a list of FDA-approved mucoadhesive, mucus-penetrating, and mucolytic drug delivery systems is reviewed. In summary, this review highlights the progress made in developing mucus-interacting systems, both at a research-scale and commercial-scale level, and describes the theoretical basis for each type of system.

Chitosan and Sodium Alginate Implementation as Pharmaceutical Excipients in Multiple-Unit Particulate Systems

This study aimed to prepare and evaluate pellets containing acyclovir as a model drug. Pellets were prepared by the extrusion–spheronization process. Aqueous solutions of natural marine polymers (sodium alginate, chitosan) were compared to semi-synthetic hydroxypropyl methylcellulose (HPMC) in the role of binders. The study focused on the characterization of the pellet properties that are crucial for the formulation of the final dosage form, such as in multi-unit pellet system (MUPS) tablets or hard gelatin capsules filled with the pellets. Finally, the mentioned dosage forms were tested for drug dissolution. The morphology of pellets observed by scanning electron microscopy correlated with the shape evaluation performed by dynamic image analysis. Sodium alginate pellets exhibited the lowest value of sphericity (0.93), and many elongated rods and dumbbells were observed in this batch. Chitosan pellets had the highest value of sphericity (0.97) and were also less rough on the surface. The pellets maintained a constant surface geometry during the dissolution studies; they only reduced in size. The most significant reduction in size and weight was assessed after 2 h of dissolution testing. This fact was in line with the drug release from pellets in capsules or MUPS tablets, which was massive during the first hour, in both cases. The dissolution profiles of all of the batches were comparable.

Surveying the Oral Drug Delivery Avenues of Novel Chitosan Derivatives

Chitosan has come a long way in biomedical applications: drug delivery is one of its core areas of imminent application. Chitosan derivatives are the new generation variants of chitosan. These modified chitosans have overcome limitations and progressed in the area of drug delivery. This review briefly surveys the current chitosan derivatives available for biomedical applications. The biomedical applications of chitosan derivatives are revisited and their key inputs for oral drug delivery have been discussed. The limited use of the vast chitosan resources for oral drug delivery applications, speculated to be probably due to the interdisciplinary nature of this research, is pointed out in the discussion. Chitosan-derivative synthesis and practical implementation for oral drug delivery require distinct expertise from chemists and pharmacists. The lack of enthusiasm could be related to the inadequacy in the smooth transfer of the synthesized derivatives to the actual implementers. With thiolated chitosan derivatives predominating the oral delivery of drugs, the need for representation from the vast array of ready-to-use chitosan derivatives is emphasized. There is plenty to explore in this direction.

Gastric acid-response chitosan/alginate/tilapia collagen peptide composite hydrogel: Protection effects on alcohol-induced gastric mucosal injury

Long-term excessive alcohol intake can easily lead to gastritis, gastric ulcer, and gastric bleeding. In this paper, the gastric acid-responsive hydrogel of CS-NAC/alginate/tilapia collagen peptide (CS-NAC/ALG/TCP) was developed. Its structure and properties were determined. The alcohol-induced gastric mucosal injury models in mice were established to evaluate the protective effects of CS-NAC/ALG/TCP. The results showed that CS-NAC/ALG/TCP was successfully fabricated, and it showed a sustained release of TCP, strong mucoadhesion, and excellent biodegradability in vitro. In the animal experiments, CS-NAC/ALG/TCP improved the oxidative stress status of the gastric mucosa by increasing the levels of SOD, GSH, and CAT in tissues. It also down-regulated the expression of MPO, TNF-α, IL-1β, and IL-6, and increased the production of gastric protective factors such as PGE2 and NO in mouse stomach, thereby reducing the alcohol-induced inflammation and protecting the gastric mucosal injury. Besides, CS-NAC/ALG/TCP can also increase the activities of alcohol metabolism enzymes to improve alcohol metabolism, thereby reducing alcoholic damage. In conclusion, CS-NAC/ALG/TCP is a promising candidate for the treatment of alcohol-induced gastric injury.

Electro-hydrodynamic assisted synthesis of lecithin-stabilized peppermint oil-loaded alginate microbeads for intestinal drug delivery

Peppermint oil (PO) is the most prominent oil using in pharmaceutical formulations with its significant therapeutic value. In this sense, this oil is attracting considerable attention from the scientific community due to its traditional therapeutic claim, biological and pharmacological potential in recent research. An organic solvent-free and environment-friendly electrohydrodynamic assisted (EHDA) technique was employed to prepared PO-loaded alginate microbeads. The current study deals with the development, optimization, in vitro characterization, in vivo gastrointestinal tract drug distribution and ex-vivo mucoadhesive properties, antioxidant, and anti-inflammatory effects of PO-loaded alginate microbeads. The optimization results indicated the voltage and flow rate have a significant influence on microbeads size and sphericity factor and encapsulation efficiency. All these optimized microbeads showed a better drug release profile in simulated intestinal fluid (pH 6.8) at 2 h. However, a minor release was found in acidic media (pH 1.2) at 2 h. The optimized formulation showed excellent mucoadhesive properties in ex-vivo and good swelling characterization in intestine media. The microbeads were found to be well distributed in various parts of the intestine in in vivo study. PO-loaded alginate microbeads similarly showed potential antioxidant effects with drug release. The formulation exhibited possible improvement of irritable bowel syndrome (IBS) in MO-induced rats. It significantly suppressed proinflammatory cytokines, i.e., interleukin- IL-1β, and upregulated anti-inflammatory cytokine expression, i.e., IL-10. It would be a promising approach for targeted drug release after oral administration and could be considered an anti-inflammatory therapeutic strategy for treating IBS.

Potential Applications of Chitosan-Based Nanomaterials to Surpass the Gastrointestinal Physiological Obstacles and Enhance the Intestinal Drug Absorption

The small intestine provides the major site for the absorption of numerous orally administered drugs. However, before reaching to the systemic circulation to exert beneficial pharmacological activities, the oral drug delivery is hindered by poor absorption/metabolic instability of the drugs in gastrointestinal (GI) tract and the presence of the mucus layer overlying intestinal epithelium. Therefore, a polymeric drug delivery system has emerged as a robust approach to enhance oral drug bioavailability and intestinal drug absorption. Chitosan, a cationic polymer derived from chitin, and its derivatives have received remarkable attention to serve as a promising drug carrier, chiefly owing to their versatile, biocompatible, biodegradable, and non-toxic properties. Several types of chitosan-based drug delivery systems have been developed, including chemical modification, conjugates, capsules, and hybrids. They have been shown to be effective in improving intestinal assimilation of several types of drugs, e.g., antidiabetic, anticancer, antimicrobial, and anti-inflammatory drugs. In this review, the physiological challenges affecting intestinal drug absorption and the effects of chitosan on those parameters impacting on oral bioavailability are summarized. More appreciably, types of chitosan-based nanomaterials enhancing intestinal drug absorption and their mechanisms, as well as potential applications in diabetes, cancers, infections, and inflammation, are highlighted. The future perspective of chitosan applications is also discussed.

Mucoadhesive gastroretentive microparticulate system for programmed delivery of famotidine and clarithromycin

AIM

The present research was aimed to develop thiolated polyacrylic acid (TPA) based microspheres (MSPs) containing famotidine (FX) and clarithromycin (CLX).

METHODS

TPA was synthesised from polyacrylic acid and l-cysteine in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDAC). The prepared TPA was characterised using FT-IR (Fourier transform-infra red), ¹H-NMR (proton nuclear magnetic resonance) spectroscopy, P-XRD (powder X ray diffraction) method, and zeta potential. The analytical tools have supported the formation of TPA. The thiolated microspheres were prepared by emulsion solvent evaporation method using 0.75% w/v polymer concentration and stirring at 400 rpm for 8 hr.

RESULTS

The average particle size and zeta potential of optimised formulation was found to be 25.2 ± 1.87 μm and -26.68 mV, respectively. The entrapment efficiency of the optimised formulation was obtained 67.20% for FX and 70.20% for CLX. The developed microspheres were swelled only in 4 h from 0.5 to 0.9. The in vitro mucoadhesive study and in vitro drug release studies demonstrated that microspheres showed mucoadhesive property. In in vitro drug release studies, the release of FX and CLX were observed to be 58.68% and 60.48%, respectively from microspheres in 8 h. The thiolated microspheres showed higher adhesion time (7.0 ± 0.8 h) in comparison to the plain microspheres (2.6 ± 0.4 h).

CONCLUSION

The prepared TPA based mucoadhesive microspheres can be utilised as carriers for the treatment of peptic ulcer caused by Helicobacter pylori which will offer enhanced residence time for the rational drug combination in the gastric region.

Thiolated Chitosans: A Multi-talented Class of Polymers for Various Applications

Various properties of chitosan can be customized by thiolation for very specific needs in a wide range of application areas. Since the discovery of thiolated chitosans, many studies have proven their advantageous characteristics, such as adhesion to biological surfaces, adjustable cross-linking and swelling behavior, controllable drug release, permeation as well as cellular uptake enhancement, inhibition of efflux pumps and enzymes, complexation of metal ions, antioxidative properties, and radical scavenging activity. Simultaneously, these polymers remain biodegradable without increased toxicity. Within this Review, an overview about the different possibilities to covalently attach sulfhydryl ligands to the polymeric backbone of chitosan is given, and the resulting versatile physiochemical properties are discussed in detail. Furthermore, the broad spectrum of applications for thiolated chitosans in science and industry, ranging from their most advanced use in pharmaceutical and medical science over wastewater treatment to the impregnation of textiles, is addressed.

Encapsulation of Black Seed Oil in Alginate Beads as a pH-Sensitive Carrier for Intestine-Targeted Drug Delivery: In Vitro, In Vivo and Ex Vivo Study

Black seed oil (BSO) has been used for various therapeutic purposes around the world since ancient eras. It is one of the most prominent oils used in nutraceutical formulations and daily consumption for its significant therapeutic value is common phenomena. The main aim of this study was to develop alginate-BSO beads as a controlled release system designed to control drug release in the gastrointestinal tract (GIT). Electrospray technology facilitates formulation of small and uniform beads with higher diffusion and swelling rates resulting in process performance improvement. The effect of different formulation and process variables was evaluated on the internal and external bead morphology, size, shape, encapsulation efficiency, swelling rate, in vitro drug release, release mechanism, ex vivo mucoadhesive strength and gastrointestinal tract qualitative and quantitative distribution. All the formulated beads showed small sizes of 0.58 ± 0.01 mm (F8) and spherical shape of 0.03 ± 0.00 mm. The coefficient of weight variation (%) ranged from 1.37 (F8) to 3.93 (F5) ng. All formulations (F1–F9) were studied in vitro for release characteristics and swelling behaviour, then the release data were fitted to various equations to determine the exponent (ns), swelling kinetic constant (ks), swelling rate (%/h), correlation coefficient (r²) and release kinetic mechanism. The oil encapsulation efficiency was almost complete at 90.13% ± 0.93% in dried beads. The maximum bead swelling rate showed 982.23 (F8, r² = 0.996) in pH 6.8 and the drug release exceeded 90% in simulated gastrointestinal fluid (pH 6.8). Moreover, the beads were well distributed throughout various parts of the intestine. This designed formulation could possibly be advantageous in terms of increased bioavailability and targeted drug delivery to the intestine region and thus may find applications in some diseases like irritable bowel syndrome.

Hydrophilic Poly(urethanes) Are an Effective Tool for Gastric Retention Independent of Drug Release Rate

Acyclovir is a poorly permeable, short half-life drug with poor colonic absorption, and current conventional controlled release formulations are unable to decrease the frequency of administration. We designed acyclovir dosage forms to be administered less frequently by being retained in the stomach and releasing drug over an extended duration. We developed a conventional modified-release matrix tablet to sustain the release of acyclovir and surrounded it with a hydrophilic poly(urethane) layer. When hydrated, the porous poly(urethane) swells to a size near or beyond that of the relaxed pylorus diameter and does not affect drug release rate. We demonstrated that the formulation is retained in the stomach for extended durations as it slowly releases drug, allowing for similar area under the curve but delayed t_max relative to a nongastroretentive control tablet. Unlike many other gastroretentive formulations, this dosage form design decouples drug release rate from gastric retention time, allowing them to be modulated independently. It also effectively retains in the stomach regardless of the prandial state, differentiating from other approaches. Our direct observation of excised rat stomachs allowed for a rigorous assessment of the impact of polymer swelling extent and the prandial state on both the dosage form integrity and retention time.

Injectable microfluidic hydrogel microspheres based on chitosan and poly(ethylene glycol) diacrylate (PEGDA) as chondrocyte carriers

Chitosan/PEGDA double-network hydrogel microspheres prepared by microfluidic method as chondrocyte carriers for bottom-up cartilage tissue engineering.

Probing the effect of various lipids and polymer blends on clopidogrel encapsulated floating microcarriers

BACKGROUND

Clopidogrel (CLOP) is an antiplatelet drug with poor solubility in intestinal fluid, which limits its bioavailability after oral administration.

OBJECTIVES

Current study focuses on developing site-specific floating microcarriers of CLOP using solvent diffusion evaporation method (SDEM) for retaining the drug in the stomach, thus improving the solubility of drug for better absorption.

METHODS

SDEM was employed to formulate floating microcarriers using lipidic excipients, namely Gelucires (GL) to impart floating properties, in combination with ethyl cellulose as release retarding polymer.

RESULTS

Prepared particles were 169 ± 6 μm to 375 ± 13 μm in size, whilst encapsulation efficiency was ranged from 39.6 ± 0.60% to 96.50 ± 3.50%. Electron micrographs depicted discrete spherical microcarriers with porous structure, which amplified with increasing HLB value of GL and concentration of Eudragit E100. FTIR study confirmed absence of major drug polymer interactions while DSC and XRD studies revealed the presence of non-crystalline nature of drug in all formulations. Drug release at pH 1.2 enhanced more than 2-folds with increasing HLB value with 32% cumulative drug release for GL 43/01 and 69% for GL 50/13. More interestingly, adding various proportions of Eudragit E100 to GL 43/01 based formulations resulted in increased drug release as high as 71%. In all formulations, the drug release followed diffusion dependent process.

CONCLUSION

It is envisaged that this formulation strategy for CLOP is promising and could possibly be tested in future for its in vivo performance. Graphical abstract Lipid based floating microcarriers of clopidogrel.

In Vitro and In Vivo Test Methods for the Evaluation of Gastroretentive Dosage Forms

More than 50 years ago, the first concepts for gastroretentive drug delivery systems were developed. Despite extensive research in this field, there is no single formulation concept for which reliable gastroretention has been demonstrated under different prandial conditions. Thus, gastroretention remains the holy grail of oral drug delivery. One of the major reasons for the various setbacks in this field is the lack of predictive in vitro and in vivo test methods used during preclinical development. In most cases, human gastrointestinal physiology is not properly considered, which leads to the application of inappropriate in vitro and animal models. Moreover, conditions in the stomach are often not fully understood. Important aspects such as the kinetics of fluid volumes, gastric pH or mechanical stresses have to be considered in a realistic manner, otherwise, the gastroretentive potential as well as drug release of novel formulations cannot be assessed correctly in preclinical studies. This review, therefore, highlights the most important aspects of human gastrointestinal physiology and discusses their potential implications for the evaluation of gastroretentive drug delivery systems.

Chitin/Chitosan: Versatile Ecological, Industrial, and Biomedical Applications

Chitin is a linear polysaccharide of N-acetylglucosamine, which is highly abundant in nature and mainly produced by marine crustaceans. Chitosan is obtained by hydrolytic deacetylation. Both polysaccharides are renewable resources, simply and cost-effectively extracted from waste material of fish industry, mainly crab and shrimp shells. Research over the past five decades has revealed that chitosan, in particular, possesses unique and useful characteristics such as chemical versatility, polyelectrolyte properties, gel- and film-forming ability, high adsorption capacity, antimicrobial and antioxidative properties, low toxicity, and biocompatibility and biodegradability features. A plethora of chemical chitosan derivatives have been synthesized yielding improved materials with suggested or effective applications in water treatment, biosensor engineering, agriculture, food processing and storage, textile additives, cosmetics fabrication, and in veterinary and human medicine. The number of studies in this research field has exploded particularly during the last two decades. Here, we review recent advances in utilizing chitosan and chitosan derivatives in different technical, agricultural, and biomedical fields.

Co-encapsulation of acyclovir and curcumin into microparticles improves the physicochemical characteristics and potentiates in vitro antiviral action: Influence of the polymeric composition

The present study developed and characterized microparticles formulations containing acyclovir and curcumin co-encapsulated in order to overcome the biopharmaceutical limitations and increase the antiviral effect of both drugs. The microparticles were prepared by a spray drying methodology following the ratio 1:3 (drug:polymer), which were made by hydroxypropylmethylcellulose (HPMC) and/or Eudragit® RS100 (EUD). The MP-1 formulation was composed of HPMC and EUD (1:1), MP-2 formulation was composed only of HPMC and MP-3 formulation was composed only of EUD. All formulations showed yielding around 50% and acceptable powder flowability. Drug content determination around 82.1-96.8% and 81.8-87% for acyclovir and curcumin, respectively. The microparticles had spherical shape, size within 11.5-15.3 μm, unimodal distribution and no chemical interactions among the components of the formulations. Of particular importance, the polymeric composition considerably influenced on the release profile of the drugs. The in vitro release experiment demonstrated that the microencapsulation provided a sustained release of acyclovir as well as increased the solubility of curcumin. Besides, mathematical modeling indicated that the experimental fit biexponential equation. Importantly, drugs microencapsulation promoted superior antiviral effect against BoVH-1 virus in comparison to their free form, which could be attributed to the improvement in the aforementioned physicochemical parameters. Therefore, these formulations could be promising technological drug carriers for acyclovir and curcumin, which highlight the great offering a potential alternative treatment for viral herpes.

Interactions of mussel-inspired polymeric nanoparticles with gastric mucin: Implications for gastro-retentive drug delivery

Mussel-inspired polydopamine (pD) coatings have several unique characteristics such as durability, versatility, and robustness. In this study, we have designed pD-coated nanoparticles (NPs) of methoxy polyethylene glycol-b-poly(ε-caprolactone) (mPEG-PCL@pD) as prospective nanoscale mucoadhesive platforms for gastro-retentive drug delivery. Successful pD coating on the NPs was confirmed by Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy. Mucoadhesion of pD-coated NPs was investigated in vitro using commercially available mucin under stomach lumen-mimetic conditions. Mucin-NP interactions were monitored by dynamic light scattering, which showed a significant change in particle size distribution of pD-coated NPs at mucin/NP ratios of 1:1, 1:2, and 1:4w/w. Turbidity measurements indicated the formation of large mucin-NP aggregates causing a significant increase in turbidity at mucin/NP ratios of 2:1 and 4:1w/w. pD-coated NPs exhibited a significantly higher mucin adsorption ability compared to uncoated NPs at mucin/NP ratios of 1:4, 1:2, and 1:1w/w. Zeta potential measurements demonstrated that mucin-pD-coated NP interactions were not electrostatic in nature. An ex vivo wash-off test conducted using excised sheep stomach revealed that 78% of pD-coated NPs remained attached to the mucosa after 8h of incubation, compared to only 33% of uncoated NPs. In vitro release of rifampicin, used as a model drug, showed a similar controlled release profile from both pD-coated and uncoated NPs. Our results serve to expand the versatility of mussel-inspired coatings to the design of mucoadhesive nanoscale vehicles for oral drug delivery.

Design of porous Eudragit® L beads for floating drug delivery by wax removal technique

The aim of this study was to design porous matrix beads for floating drug delivery using enteric polymer, Eudragit^® L and various amounts of waxes (0, 0.1, 0.5, 1, 2 and 3% w/w). In this study, wax containing cetyl alcohol and white petrolatum was utilized to produce pores using a wax removal technique. To prepare the beads, Eudragit^® L, metronidazole and wax were dissolved in acetone and then extruded into dichloromethane. The effect of the amount of wax on the floating and drug release behavior of the Eudragit^® L beads was determined. After the extruded product was immersed in dichloromethane, wax dissolved out from the formed beads, resulting in a porous structure. The prepared beads could float in simulated gastric fluid for more than 10 hours. Different amounts of wax had an effect on the drug release. We found that when the percentage of wax increased, the drug release was higher while the beads remained floating. The results suggest that Eudragit^® L beads could be used as a carrier for an intragastric floating drug delivery system.

A Janus Mucoadhesive and Omniphobic Device for Gastrointestinal Retention

A novel Janus device with omniphobic and mucoadhesive sides that exhibit the unique capacity for antifouling and extended gastrointestinal retention is fabricated. This system enables repulsion of the food and fluid stream by the luminal-facing omniphobic side and allows attachment to the gastrointestinal mucosa by the mucoadhesive side.

Cellulose Acetate 398-10 Asymmetric Membrane Capsules for Osmotically Regulated Delivery of Acyclovir

The study was aimed at developing cellulose acetate asymmetric membrane capsules (AMCs) of acyclovir for its controlled delivery at the absorption site. The AMCs were prepared by phase inversion technique using wet process. A 2(3) full factorial design assessed the effect of independent variables (level(s) of polymer, pore former, and osmogen) on the cumulative drug release from AMCs. The buoyant optimized formulation F7 (low level of cellulose acetate; high levels of both glycerol and sodium lauryl sulphate) displayed maximum drug release of 97.88 ± 0.77% in 8 h that was independent of variation in agitational intensity and intentional defect on the cellulose acetate AMC. The in vitro data best fitted zero-order kinetics (r (2) = 0.9898). SEM micrograph of the transverse section confirmed the asymmetric nature of the cellulose acetate capsular membrane. Statistical analysis by Design Expert software indicated no interaction between the independent variables confirming the efficiency of the design in estimating the effects of variables on drug release. The optimized formulation F7 (desirability = 0.871) displayed sustenance of drug release over the drug packed in AMC in pure state proving the superiority of osmotically active formulation. Conclusively the AMCs have potential for controlled release of acyclovir at its absorption site.

Preparation, characterization, and potential application of chitosan, chitosan derivatives, and chitosan metal nanoparticles in pharmaceutical drug delivery

Naturally occurring polymers, particularly of the polysaccharide type, have been used pharmaceutically for the delivery of a wide variety of therapeutic agents. Chitosan, the second abundant naturally occurring polysaccharide next to cellulose, is a biocompatible and biodegradable mucoadhesive polymer that has been extensively used in the preparation of micro-as well as nanoparticles. The prepared particles have been exploited as a potential carrier for different therapeutic agents such as peptides, proteins, vaccines, DNA, and drugs for parenteral and nonparenteral administration. Therapeutic agent-loaded chitosan micro- or nanoparticles were found to be more stable, permeable, and bioactive. In this review, we are highlighting the different methods of preparation and characterization of chitosan micro- and nanoparticles, while reviewing the pharmaceutical applications of these particles in drug delivery. Moreover, the roles of chitosan derivatives and chitosan metal nanoparticles in drug delivery have been illustrated.

Protective effects of alginate-chitosan microspheres loaded with alkaloids from Coptis chinensis Franch. and Evodia rutaecarpa (Juss.) Benth. (Zuojin Pill) against ethanol-induced acute gastric mucosal injury in rats

Zuojin Pill (ZJP), a traditional Chinese medicine formula, consists of Coptis chinensis Franch. and Evodia rutaecarpa (Juss.) Benth. in a ratio of 6:1 (w/w) and was first recorded in “Danxi’s experiential therapy” for treating gastrointestinal disorders in the 15th century. However, the poor solubility of alkaloids from ZJP restricted the protective effect in treating gastritis and gastric ulcer. The aim of the study was to investigate the protective mechanism of mucoadhesive microspheres loaded with alkaloids from C. chinensis Franch. and E. rutaecarpa (Juss.) Benth. on ethanol-induced acute gastric mucosal injury in rats. Surface morphology, particle size, drug loading, encapsulation efficiency, in vitro drug release, mucoadhesiveness, and fluorescent imaging of the microspheres in gastrointestinal tract were studied. The results showed that the mucoadhesive microspheres loaded with alkaloids could sustain the release of drugs beyond 12 hours and had gastric mucoadhesive property with 82.63% retention rate in vitro. The fluorescence tracer indicated high retention of mucoadhesive microspheres within 12 hours in vivo. The mucoadhesive microspheres loaded with alkaloids could reduce the gastric injury by decreasing the mucosal lesion index, increasing the percentage of inhibition and increasing the amount of mucus in the gastric mucosa in an ethanol-induced gastric mucosal injury rat model. Moreover, the mucoadhesive microspheres loaded with alkaloids reduce the inflammatory response by decreasing the levels of tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β), downregulating the mRNA expression of inducible nitric oxide synthase, TNF-α, and IL-1β in gastric mucosa. All the results indicate that mucoadhesive microspheres loaded with alkaloids could not only increase the residence time of alkaloids in rat stomach, but also exert gastroprotective effects through reducing the inflammatory response on ethanol-induced gastric mucosal damage. Thus, these microspheres could be developed as a potential controlled release drug for treatment of gastric ulcer.

The Influence of Chitosan on the Oral Bioavailability of Acyclovir--a Comparative Bioavailability Study in Humans

PURPOSE

The effects of chitosan hydrochloride on the oral absorption of acyclovir in humans were studied to confirm the absorption enhancing effects reported for in vitro and rat studies, respectively.

METHODS

A controlled, open-label, randomized, 3-phase study was conducted in 12 healthy human volunteers. Zovirax 200 mg dispersible tablets co-administered with doses of 400 and 1000 mg chitosan HCl were compared with Zovirax only.

RESULTS

The expected increased absorption of acyclovir was not observed. On the contrary, mean area under the plasma concentration-time curve (AUC0-12 h) and maximal plasma concentration (Cmax) decreased following concomitant chitosan intake (1402 versus 1017 and 982.0 ng ∙ h/ml and 373 versus 208 and 235 ng/ml, respectively). In addition, Tmax increased significantly in presence of 1000 mg of chitosan from 1 to 2 h.

CONCLUSIONS

The results of this study in human volunteers did not confirm an absorption enhancing effect of chitosan. Reference values were comparable to literature data, whereas addition of chitosan resulted in significant opposite effects on Cmax, Tmax and AUC. Additional studies are needed to investigate the cause of the discrepancy. The observed variability and complex potential interactions may complicate the use of chitosan HCl in oral pharmaceutical formulations.

Density-dependent gastroretentive microparticles motion in human gastric emptying studied using computer simulation

Density-dependent gastroretentive drug delivery systems have been used to prolong the gastric retention time of drugs since the 1960s. The design of density-dependent gastroretentive dosage forms, however, usually focuses on specific parameters rather than combines with the fluid dynamics of dosage form in the gastric emptying. Therefore, the purpose of the present study was to develop a 2-D model of multiple-phase flows for the simulation of gastric emptying and gastroretentive microparticles motion, and the influence of microparticle density, microparticle viscosity, and gastric juice viscosity on the gastric retention were studied. The recirculating flows, formed in the gastric emptying, could mix the conventional-density microparticles and transport them to the pylorus. However, the low-density microparticles remained floating on the surface of gastric juice, while the high-density microparticles could sink and deposit in the bottom of the stomach. The remaining integral area of microparticles was higher than 90% after 18.33min of simulation when the density of microparticles was lower than 550kg/m(3) or higher than 2500kg/m(3), which was higher compared to conventional-density microparticles (67.05%). These results are in good agreement with experimental data previously reported. In addition, the viscosity of microparticle and gastric juice also influenced the remaining integral area of gastroretentive microparticles. This study shows that the multiple-phase computational fluid dynamics models could provide detailed insights into the fluid dynamics of density-dependent gastroretentive microparticles in gastric emptying, which offers a powerful tool to further understand the mechanism of gastric retention for gastroretentive dosage forms and study the influence of different parameters on their ability for gastric retention.

Nanoparticle formulation by Büchi B-90 Nano Spray Dryer for oral mucoadhesion

Diabetes is considered one of the main threats to global public health in this era. It is increasing rapidly in every part of the world; the prevalence of the disease will grow to the point where 366 million people will be affected by 2030. The prevalence of diabetes mellitus (DM) in the Saudi population is high, and the majority of patients suffer from type 2 DM. Marketed oral antidiabetic drugs have indicated poor tolerability during chronic treatments, and this contributes to the moderately large proportion of type 2 DM patients that remain inadequately managed. Vildagliptin nanospheres were prepared with aminated gelatin using a spray-drying method; narrow particle-size distribution was seen at 445 nm. The angle of repose was found to be θ <33.5°. The nanospheres appeared to be spherical with a smooth surface. The drug content and percentage yield of the nanospheres were found to be 76.2%±4.6% and 83%±2%, respectively. The nanosphere-swell profile was found to be 165%±7%. The pure drug was 100% dissolved in 30 minutes, and the nanosphere formulation took 12 hours to dissolve (97.5%±2%), and followed a Korsmeyer-Peppas kinetic model with an R (2) of 0.9838. The wash-off test of nanospheres found that they exhibited an excellent mucoadhesive property at 86.7% for 8 hours. The stability-study data showed no changes in the physicochemical properties of the nanospheres, and suggested that the nanospheres be stored below room temperature. The amount of vildagliptin retained was 1.6% within 3 hours, and in comparison with the gelatin vildagliptin nanoparticles formulation, the percentage that was retained was much higher (98.2% in 12 hours).

Mucoadhesive microparticles for gastroretentive delivery: preparation, biodistribution and targeting evaluation

The aim of this research was to prepare and characterize alginate-chitosan mucoadhesive microparticles containing puerarin. The microparticles were prepared by an emulsification-internal gelatin method using a combination of chitosan and Ca²⁺ as cationic components and alginate as anions. Surface morphology, particle size, drug loading, encapsulation efficiency and swelling ratio, in vitro drug released, in vitro evaluation of mucoadhesiveness and Fluorescence imaging of the gastrointestinal tract were determined. After optimization of the formulation, the encapsulation efficiency was dramatically increased from 70.3% to 99.2%, and a highly swelling ratio was achieved with a change in particle size from 50.3 ± 11.2 μm to 124.7 ± 25.6 μm. In ethanol induced gastric ulcers, administration of puerarin mucoadhesive microparticles at doses of 150 mg/kg, 300 mg/kg, 450 mg/kg and 600 mg/kg body weight prior to ethanol ingestion significantly protected the stomach ulceration. Consequently, significant changes were observed in inflammatory cytokines, such as prostaglandin E₂ (PGE₂), tumor necrosis factor (TNF-α), interleukin 6 (IL-6), and interleukin1β (IL-1β), in stomach tissues compared with the ethanol control group. In conclusion, core-shell type pH-sensitive mucoadhesive microparticles loaded with puerarin could enhance puerarin bioavailability and have the potential to alleviate ethanol-mediated gastric ulcers.

Comparative study of in vitro release and mucoadhesivity of gastric compacts composed of multiple unit system/bilayered discs using direct compression of metformin hydrochloride

INTRODUCTION

Metformin is an oral anti-diabetic drug in the biguanide class. The goal of this study was to develop gastric-retentive MH discs in order to prolong the retention of drug in gastric mucosa.

METHODS

Two groups of metformin hydrochloride (MH) mucoadhesive gastroretentive discs were prepared: (a) bilayered discs prepared by direct compression of powders containing polymers as Carbopol 934P (CP, mucoadhesive polymer) and ethylcellulose (EC, rotardant polymer), (b) multiple unit system (microparticle) discs prepared by the emulsification, solvent evaporation, and compression technique from microparticles using polymers CP and EC. Gastric-mucoadhesive compacts were evaluated by investigating their release pattern, swelling capacity, mucoadhesion property, surface pH, and in vitro gastro-retentive time. Discs formulation was subjected to disintegration and dissolution tests by placing in 0.1 M hydrochloric acid for 8 h.

RESULTS

The production yield showed F2 microparticles of 98.80%, mean particle size of 933.25 µm and loading efficiency of 98.44%. The results showed that prepared microparticle discs had slower release than bilayered discs (p>0.05). The bilayered discs exhibited very good percentage of mucoadhesion. The results also showed a significant higher retention of mucoadhesive bilayered discs in upper gastrointestinal tract (F´1, 1:2 ratio of CP:EC). Histopathological studies revealed no gastric mucosal damage.

CONCLUSION

Mucoadhesive multiple unit system/bilayered discs interact with mucus of gastrointestinal tract and are considered to be localized or trapped at the adhesive site by retaining a dosage form at the site of action as well as improving in the intimacy of contact with underlying absorptive membrane to achieve a better therapeutic performance of anti-diabetic drug.

Formulation and Evaluation of In-vitro Characterization of Gastic-Mucoadhesive Microparticles/Discs Containing Metformin Hydrochloride

The present study involves preparation and evaluation of gastric-mucoadhesive microparticles with Metformin Hydrochloride as model drug for prolongation of gastric residence time. The microparticles were prepared by the emulsification solvent evaporation technique using polymers of Carbomer 934p (CP) and Ethylcellulose (EC). The microparticles were prepared by emulsion solvent evaporation method (O1/O2). Disc formulations were prepared by direct compression technique from microparticles. In the current study, gastric-mucoadhesive microparticles with different polymers ratios (CP:EC) were prepared and were characterized by encapsulation efficiency, particle size, flowability, mucoadhesive property and drug release studies. The best polymers ratio was 1:3 (F2) with Carbomer 934p (as mucoadhesive polymer) and ethylcellulose (as retardant polymer), respectively. The production yield microparticles F2 showed 98.80%, mean particle size 933.25 µm and loading efficiency %98.44. The results were found that microparticle discs prepared had slower release than microparticles (p > o.o5). The microparticles exhibited very good percentage of mucoadhesion and flowability properties. The release of drug was prolonged to 8 h (71.65-82.22%) when incorporated into mucoadhesive microparticles. The poor bioavailability of metformine is attributed to short retention of its dosage form at the absorption sites (in upper gastrointestinal tract). The results of mucoadhesion study showed better retention of metformine microparticles (8 h) in duodenal and jejunum regions of intestine (F1, 1:2 ratio of CP:EC). Therefore, it may be concluded that drug loaded gastric-mucoadhesive microparticles are a suitable delivery system for metformin hydrochloride, and may be used for effective management of NIDDM (Non Insulin Dependent Diabetes Mellitus).

Development and characterization of gastroretentive sustained-release formulation by combination of swelling and mucoadhesive approach: a mechanistic study

Background

Acyclovir has pharmacokinetic limitations, including poor oral bioavailability of 15%–30%, high variability, and short elimination half-life of 2.3 hours. These limitations necessitate frequent administration of acyclovir, up to five times daily, leading to poor patient compliance, which in turn leads to a reduction in therapeutic efficacy and development of resistance.

Methods

A gastroretentive sustained-release (GR) formulation of acyclovir, based on a combination of swelling and mucoadhesive mechanisms, has been developed. Composition has been optimized after evaluation of different polymers, carbomer, polyethylene oxide, and sodium alginate alone and/or in combination. GR formulations were characterized for in-process quality-control tests, drug release and release rate kinetics, similarity factor analysis, swelling index, and matrix erosion.

Results

A formulation containing a combination of carbomer and polyethylene oxide had the highest similarity of drug release compared with a target drug-release profile obtained by pharmacokinetic simulations. The measurement of mucoadhesive strength, carried out with a texture analyzer, showed that the mucoadhesive strength of the GR formulation was significantly higher than that of the immediate-release (IR) tablet. The optimized GR formulation was found to be retained in the upper part of the gastrointestinal tract for 480 minutes; the IR tablet was retained for only 90 minutes as measured using a gastrointestinal retention study in albino rabbits. The GR formulation was also found to maintain more sustained plasma concentrations than the IR tablet. Mean residence time of the GR formulation was 7 hours versus 3.3 hours for the IR formulation. The relative bioavailability of the GR formulation was 261% of the IR formulation.

Conclusion

The GR formulation of acyclovir, based on swelling and mucoadhesive mechanisms, has prolonged retention in the upper gastrointestinal tract, sustained in vitro drug release, prolonged in vivo absorption, and better bioavailability than the IR formulation. Such a formulation would improve patient compliance and increase the efficacy of therapy.

Development of mucoadhesive floating hollow beads of acyclovir with gastroretentive properties

This study aimed at improving the oral bioavailability of acyclovir (ACV) through incorporating it into gastroretentive dosage form based on floating hollow chitosan beads. Hollow chitosan beads were prepared using a solvent free, ionotropic gelation method. The effect of formulation parameters, including chitosan molecular weight and drug concentration, on bead characteristics was studied. The drug containing formulations had yields >70.5 ± 0.31%. The entrapment efficiencies for the medium molecular weight chitosan formulations (56.29 ± 0.94%-62.75 ± 0.86%) was greater than the high molecular weight chitosan formulation (29.21 ± 0.89%). The density of all formulations was below that of gastric fluid, the greatest density observed was 0.60 ± 0.01 g cm(-3). Unsurprisingly, the formulations were immediate bouyant to different degrees in both pH 1.2 and pH 6.8 media. In addition, the chitosan beads were all seen to swell in pH 1.2 media and demonstrated mucoadhesive properties. A sustained release profile was observed from the chitosan beads, the developed formulations released drug at slower rates than a marketed ACV oral tablet. The developed system has the dual advantages of being gastroretentive, to increase oral bioavailability and releasing drug in a controlled manner, to reduce the required frequency of administration thereby promoting patient adherence.