In vitro and in vivo evaluation of mucoadhesive microspheres prepared for the gastrointestinal tract using polyglycerol esters of fatty acids and a poly(acrylic acid) derivative

Injectable Modified Sodium Alginate Microspheres for Enhanced Operative Efficiency and Safety in Endoscopic Submucosal Dissection

Endoscopic submucosal dissection (ESD) is an effective method for resecting early-stage tumors in the digestive system. To achieve a low injection pressure of the injected fluid and continuous elevation of the mucosa following injection during the ESD technique, we introduced an innovative injectable sodium-alginate-based drug-loaded microsphere (Cipro-ThSA) for ESD surgery, which was generated through an emulsion reaction involving cysteine-modified sodium alginate (ThSA) and ciprofloxacin. Cipro-ThSA microspheres exhibited notable adhesiveness, antioxidant activity, and antimicrobial properties, providing a certain level of postoperative wound protection. In vitro cell assays confirmed the decent biocompatibility of the material. Lastly, according to animal experiments involving submucosal elevation of porcine colons, Cipro-ThSA microspheres ensure surgically removable lift height while maintaining the mucosa for approximately 246% longer than saline, which could effectively reduce surgical risks while providing sufficient time for operation. Consequently, the Cipro-ThSA microsphere holds great promise as a novel submucosal injection material, in terms of enhancing the operational safety and effectiveness of ESD surgery.

Pharmacokinetics of doxycycline hyclate in pigs with a new feed premix formulation

This study aimed to evaluate the administration of doxycycline hyclate in a long-acting pharmaceutical preparation in pigs when administered either ad libitum as a feed medication or an oral bolus dose. In all instances, the studied dose was 20 mg/kg b.w. A total of 48 healthy crossbred, castrated male pigs (Landrace-Yorkshire) weighing 23 ± 4.3 kg were included in this trial. They were randomly assigned to six groups as follows: two groups for the experimental prototype 1 of doxycycline hyclate administering it ad libitum (Fad-lib) or as forced bolus (Fbolus); two groups for the experimental prototype 2 of doxycycline hyclate as for the former groups (FCad-lib and FCbolus), and two control groups receiving the same dose of doxycycline hyclate, but of a commercial premix, also as previously explained (Cbolus and Cad-lib). Statistical analysis of the mean pharmacokinetic values was carried out with Kruskal-Wallis and Dunn's tests. The relative bioavailability (Fr) of the best prototype, when administered ad libitum (FCad-lib), was five times larger than the reference group (Cadlib). These results allow the proposal that the referred differences achieved in the presented prototypes can mark a notable clinical difference, particularly in pathogens with some resistance.

Sustain-release lipid-liquid crystal formulations of pexiganan against Helicobacter pylori infection: in vitro evaluation in C57BL/6 mice

INTRODUCTION

The Gram-negative bacterium Helicobacter pylori, H. pylori, is associated with significant digestive disorders. However, the effectiveness of bacterial eradication is declining due to drug resistance. A potent anti-H. pylori activity is shown by the natural antimicrobial peptide pexiganan.

OBJECTIVE

The current study aimed to evaluate the effectiveness of pexiganan and its lipid-liquid crystals (LLCs) in inducing Helicobacter pylori in mice.

METHODS

In this experimental study, H. pylori infection was first induced in C57BL/6 mice. Secondly, the antibacterial efficacy of pexiganan and its LLCs formulations was investigated to eliminate H. pylori infection.

RESULTS

The H. pylori infection could not be completely eradicated by pexiganan peptide alone. However, incorporating pexiganan within the LLC formulation resulted in an increased elimination of H. pylori. Under the H&E strain, the pexiganan-LLCs formulation revealed minimal mucosal alterations and a lower amount of inflammatory cell infiltration in the stomach compared to the placebo.

CONCLUSION

Clarithromycin was more effective than pexiganan at all tested concentrations. Furthermore, the pexiganan-loaded LLCs exhibited superior efficacy in curing H. pylori infection in a mouse model compared to pexiganan alone. This formulation can enhance H. pylori clearance while mitigating the adverse effects, typically associated with conventional drugs, leading to a viable alternative to current treatment options.

Water-Absorbing Bioadhesive Poly(Acrylic Acid)/Polyvinylpyrrolidone Complex Sponge for Hemostatic Agents

BACKGROUND

Poly(acrylic acid) (PAA) is a water-soluble synthetic polymer with tissue-adhesive properties. When PAA is mixed with polyvinylpyrrolidone (PVP) in water, it forms a water-insoluble precipitate that neither swells nor adheres to tissues.

METHODS AND RESULTS

We developed a novel solid/solution interface complexation method to obtain a water-swellable PAA/PVP complex. First, PAA solution was dried up in a vessel to form a film. The PAA film was then immersed in an aqueous PVP solution to obtain a highly swollen PAA/PVP hydrogel. Heat drying of the hydrogel yielded a transparent film, while freeze-drying the hydrogel provided a soft sponge. Both the PAA/PVP film and sponge could be re-swelled by water to obtain a bioadhesive gel. A relatively larger specific surface area of the sponge than that of the film led to a more rapid swelling and water absorption behavior and quick adhesion to tissues. The addition of hyaluronic acid (HA) improved the mechanical characteristics of the sponges. PAA/PVP/HA sponges had low cytotoxicity, and they exhibited high hemostatic efficiency in clinical studies after dialysis treatment or tooth extraction, even in patients on antithrombotic drugs.

CONCLUSIONS

Such bioadhesive materials consisting of low-toxicity polymers have a high potential for use in medical hemostatic devices.

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.

Preparation of a Bioadhesive Poly(Acrylic Acid)/Polyvinylpyrrolidone Complex Gel and Its Clinical Effect on Dental Hemostasis

Poly(acrylic acid) (PAA) is a water-soluble synthetic polymer that exhibits bioadhesive properties and has been applied in various novel medical devices, such as drug-delivery carriers and hemostatic agents. PAA forms a water-insoluble complex when mixed with polyvinylpyrrolidone (PVP). If PAA and PVP are mixed in water, they form an aggregated precipitate, which neither swells nor adheres to tissues. The formation of the hydrophobic complex was caused by hydrophobic interactions between the main chains of both polymers aligned the same as a zipper. To hinder the zipper-like alignment of the polymer main chains, hyaluronic acid (HA), a macromolecular viscous polysaccharide, was added to the PVP solution prior to complex formation. When the initial concentration of PAA was lower than 0.05%, HA effectively prevented the aggregation of PAA/PVP complexes and resulted in a slightly clouded suspension. Freeze-drying of the mixture yielded a soft white sponge, which could immediately swell in water to form a highly bioadhesive hydrogel. The PAA/PVP complex prepared with HA exhibited high hemostatic efficiency in clinical studies, even in patients on antithrombotic drugs.

The Nano-Intestine Interaction: Understanding the Location-Oriented Effects of Engineered Nanomaterials in the Intestine

Engineered nanomaterials (ENMs) are used in food additives, food packages, and therapeutic purposes owing to their useful properties, Therefore, human beings are orally exposed to exogenous nanomaterials frequently, which means the intestine is one of the primary targets of nanomaterials. Consequently, it is of great importance to understand the interaction between nanomaterials and the intestine. When nanomaterials enter into gut lumen, they inevitably interact with various components and thereby display different effects on the intestine based on their locations; these are known as location-oriented effects (LOE). The intestinal LOE confer a new biological-effect profile for nanomaterials, which is dependent on the involvement of the following biological processes: nano-mucus interaction, nano-intestinal epithelial cells (IECs) interaction, nano-immune interaction, and nano-microbiota interaction. A deep understanding of NM-induced LOE will facilitate the design of safer NMs and the development of more efficient nanomedicine for intestine-related diseases. Herein, recent progress in this field is reviewed in order to better understand the LOE of nanomaterials. The distant effects of nanomaterials coupling with microbiota are also highlighted. Investigation of the interaction of nanomaterials with the intestine will stimulate other new research areas beyond intestinal nanotoxicity.

Colon targeted bioadhesive pellets of curcumin and cyclosporine for improved management of inflammatory bowel disease

The objective of the present work was to develop and optimize multiparticulate pH-dependent bioadhesive pellets of curcumin and cyclosporine for the management of intestinal bowel disease (IBD). The bioadhesive sustained release pellets were intended for targeting the affected site for an improved therapeutic effect. Bioadhesive pellet cores of curcumin and cyclosporine were formulated using Carbopol 940 (CP940) and hydroxypropyl cellulose (HPC-H) by the extrusion/spheronization method, and drug delivery to the colon was controlled by the pH-sensitive polymer Eudragit® S100. Microcrystalline cellulose (Avicel PH101) was found to be the best forming agent for pellet core. The ratio of CP940 to HPC-H was kept at 1:1 to achieve 100% bioadhesion. The in vitro dissolution profiles of coated pellets depicted that 12.327 ± 0.342% of curcumin and 14.751 ± 0.112% of cyclosporine were released at the end of 6 h (at pH 6.8), whereas 71.278 ± 0.100% of curcumin and 76.76 ± 0.195% of cyclosporine were released at the end of 24 h (at pH 7.4). The drug release profile was found to follow zero-order kinetics for both drugs. The selected formulation was evaluated on an acetic acid-induced ulcerative colitis in the rat model to evaluate the efficiency of drug-loaded pellets coated with Eudragit®S100. The pharmacodynamic study revealed the therapeutic efficacy of Eudragit®S100-coated pellets of curcumin and cyclosporine in alleviating the conditions of the acetic acid-induced colitis model as reflected by weight gain as well as improvement of clinical, macroscopic and microscopic parameters of induced colitis, as compared with free curcumin and cyclosporine. The combination of curcumin and cyclosporine has been proven to have a synergistic effect for the successful management of IBD when used in a low dose as compared with individual drugs with high doses. Hence, curcumin- and cyclosporine-loaded bioadhesive pellets may act as a promising targeted drug delivery system in the management of IBD. Graphical abstract.

Development of Microspheres Based on Thiol-Modified Sodium Alginate for Intestinal-Targeted Drug Delivery

Bioactive peptide drugs are mostly delivered by parenteral administration, which brings great pain and risks to patients. Oral administration is an acceptable alternative form. However, peptide drugs are extremely sensitive to the strong acidic environment in the stomach after oral administration. They would be degraded by pepsin and trypsin in the gastrointestinal tract. Herein, we present microspheres for intestinal-targeted peptides drug delivery through oral administration. Sodium alginate was reacted with l-cysteine to bring it into thiol groups. Then sodium alginate-l-cysteine conjugates were mixed with native sodium alginate and emulsified by an improved method. Ca²⁺ was used to fix the emulsion to get the microspheres. Bovine serum albumin was used as the simulating drug to assess the feasibility of microspheres as intestinal delivery carriers. The results showed that the microspheres exhibited spherical properties and narrow size distribution. The drug-loading capacity of microspheres was not compromised after thiol-modification. It is interesting that the microspheres can maintain structural integrity and hold drugs in the strong acidic environment in the stomach. Conversely, the microspheres presented sustained intestinal-targeted drugs release ability as expected. Moreover, thiol-modification further improved the adherence ability of microspheres on the inner walls of the small intestine, which is good for enhancing drug permeability. In sum, the microspheres based on thiol-modified sodium alginate have promising applications as intestinal-targeted macromolecular drug carriers.

Engineering the Mucus Barrier

Mucus selectively controls the transport of molecules, particulate matter, and microorganisms to the underlying epithelial layer. It may be desirable to weaken the mucus barrier to enable effective delivery of drug carriers. Alternatively, the mucus barrier can be strengthened to prevent epithelial interaction with pathogenic microbes or other exogenous materials. The dynamic mucus layer can undergo changes in structure (e.g., pore size) and/or composition (e.g., protein concentrations, mucin glycosylation) in response to stimuli that occur naturally or are purposely administered, thus altering its barrier function. This review outlines mechanisms by which mucus provides a selective barrier and methods to engineer the mucus layer from the perspective of strengthening or weakening its barrier properties. In addition, we discuss strategic design of drug carriers and dosing formulation properties for efficient delivery across the mucus barrier.

Sortase-Dependent Proteins Promote Gastrointestinal Colonization by Enterococci

The human gastrointestinal tract (GIT) is inhabited by a dense microbial community of symbionts. Enterococci are among the earliest members of this community and remain core members of the GIT microbiota throughout life. Enterococci have also recently emerged as opportunistic pathogens and major causes of nosocomial infections. Although recognized as a prerequisite for infection, colonization of the GIT by enterococci remains poorly understood. One way that bacteria adapt to dynamic ecosystems like the GIT is through the use of their surface proteins to sense and interact with components of their immediate environment. In Gram-positive bacteria, a subset of surface proteins relies on an enzyme called sortase for covalent attachment to the cell wall. Here, we show that the housekeeping sortase A (SrtA) enzyme promotes intestinal colonization by enterococci. Furthermore, we show that the enzymatic activity of SrtA is key to the ability of Enterococcus faecalis to bind mucin (a major component of the GIT mucus). We also report the GIT colonization phenotypes of E. faecalis mutants lacking selected sortase-dependent proteins (SDPs). Further examination of the mucin binding ability of these mutants suggests that adhesion to mucin contributes to intestinal colonization by E. faecalis.

Rheological analysis and mucoadhesion: A 30 year-old and still active combination

At the end of 80s and in the early 90s, an increasing interest in the development of mucoadhesive formulations occurred in the pharmaceutical field. Such formulations, prolonging the drug permanence on the mucosa of action/absorption, improve drug availability/bioavailability and therefore its therapeutic effectiveness. Among the various methods reported in the literature for the evaluation of the mucoadhesive properties of polymers, in the early 1990s, the study of the rheological variation of the polymer solutions after mixing with a mucin solution/dispersion has been proposed as an approach to measure the strength of the mucoadhesive joint. Even today, both viscosity and viscoelastic measurements are used to evaluate the ability of polymers and formulations to adhere to the mucosa of application/action. This review aims at providing an overview of the rheological approaches employed in the development and characterization of mucoadhesive formulation, highlighting their advantages and disadvantages. To do this the scientific path that, since the beginning of the 90s, has led to the affirmation of the rheological analysis as a useful tool for the evaluation of the strength of the mucoadhesive bond is retraced.

Engineering nanomaterials to overcome the mucosal barrier by modulating surface properties

Although nanotechnology has been investigated during recent years to increase the bioavailability and therapeutic effects of mucosal administrated drugs, numerous barriers (e.g., pH environment, enzymes and mucus) still limit the delivery efficiency. And the epithelium would also affect the systemic mucosal drug delivery. Amongst all the barriers, the protective mucus has drawn more and more attention, which strongly hinders the accessibility of nanovehicles to epithelium. Therefore, trials to conquer the mucus barrier have been designed using two controversial strategies: mucoadhesion and mucus-penetration. This review summarizes the influence of mucus layer on nanomaterials and introduces the modification strategies by modulating surface properties (i.e., hydrophilicity/hydrophobicity and surface charge) to overcome mucus barriers. Furthermore, it also reviews advanced modification methods to meet the different surface requirements of nanovehicles to overcome mucus and epithelium barriers in systemic mucosal delivery.

Evaluation of the Efficacy and Safety of DA-9601 versus Its New Formulation, DA-5204, in Patients with Gastritis: Phase III, Randomized, Double-Blind, Non-Inferiority Study

This study compared the efficacy of DA-9601 (Dong-A ST Co., Seoul, Korea) and its new formulation, DA-5204 (Dong-A ST Co.), for treating erosive gastritis. This phase III, randomized, multicenter, double-blind, non-inferiority trial randomly assigned 434 patients with endoscopically proven gastric mucosal erosions into two groups: DA-9601 3 times daily or DA-5,204 twice daily for 2 weeks. The final analysis included 421 patients (DA-5204, 209; DA-9601, 212). The primary endpoint (rate of effective gastric erosion healing) and secondary endpoints (cure rate of endoscopic erosion and gastrointestinal [GI] symptom relief) were assessed using endoscopy after the treatment. Drug-related adverse events (AEs), including GI symptoms, were also compared. At week 2, gastric healing rates with DA-5204 and DA-9601 were 42.1% (88/209) and 42.5% (90/212), respectively. The difference between the groups was -0.4% (95% confidence interval, -9.8% to 9.1%), which was above the non-inferiority margin of -14%. The cure rate of gastric erosion in both groups was 37.3%. The improvement rates of GI symptoms with DA-5204 and DA-9601 were 40.4% and 40.8%, respectively. There were no statistically significant differences between the two groups in both secondary endpoints. AEs were reported in 18 (8.4%) patients in the DA-5204 group and 19 (8.8%) in the DA-9601 group. Rates of AE were not different between the two groups. No serious AE or adverse drug reaction (ADR) occurred. These results demonstrate the non-inferiority of DA-5204 compared to DA-9601. DA-5204 is as effective as DA-9601 in the treatment of erosive gastritis. Registered randomized clinical trial at ClinicalTrials.gov (NCT02282670).

Enhanced gastric retention and drug release via development of novel floating microspheres based on Eudragit E100 and polycaprolactone: synthesis and in vitro evaluation

Eudragit E 100 and polycaprolactone (PCL) floating microspheres for enhanced gastric retention and drug release were successfully prepared by oil in water solvent evaporation method. Metronidazole benzoate, an anti-protozoal drug, was used as a model drug. Polyvinyl alcohol was used as an emulsifier. The prepared microspheres were observed for % recovery, % degree of hydration, % water uptake, % drug loading, % buoyancy and % drug release. The physico-chemical properties of the microspheres were studied by calculating encapsulation efficiency of microspheres and drug release kinetics. Drug release characteristics of microspheres were studied in simulated gastric fluid and simulated intestinal fluid i.e., at pH 1.2 and 7.4 respectively. Fourier transform infrared spectroscopy was used to reveal the chemical interaction between drug and polymers. Scanning electron microscopy was conducted to study the morphology of the synthesized microspheres.

Floating mucoadhesive alginate beads of amoxicillin trihydrate: A facile approach for H. pylori eradication

This study investigates the design of sunflower oil entrapped floating and mucoadhesive beads of amoxicillin trihydrate using sodium alginate and hydroxypropyl methylcellulose as matrix polymers and chitosan as coating polymer to localize the antibiotic at the stomach site against Helicobacter pylori. Beads prepared by ionotropic gellation technique were evaluated for different physicochemical, in-vitro and in-vivo properties. Beads of all batches were floated for >24h with a maximum lag time of 46.3±3.2s. Scanning electron microscopy revealed that the beads were spherical in shape with few oil filled channels distributed throughout the surfaces and small pocket structures inside the matrix confirming oil entrapment. Prepared beads showed good mucoadhesiveness of 75.7±3.0% to 85.0±5.5%. The drug release profile was best fitted to Higuchi model with non fickian driven mechanism. The optimized batch showed 100% Helicobacter pylori growth inhibition in 15h in in-vitro culture. Furthermore, X-ray study in rabbit stomach confirmed the gastric retention of optimized formulation. The results exhibited that formulated beads may be preferred to localize the antibiotic in the gastric region to allow more availability of antibiotic at gastric mucus layer acting on Helicobacter pylori, thereby improving the therapeutic efficacy.

PEGDA hydrogels as a replacement for animal tissues in mucoadhesion testing

Utilization of animal parts in ex-vivo mucoadhesion assays is a common approach that presents many difficulties due to animal rights issues and large variance between animals. This study examines the suitability of two PEGDA (poly(ethylene glycol) diacrylate) based hydrogels to serve as tissue mimetics for mucoadhesion evaluation. One hydrogel, termed PEGDA-QT, was composed of pentaerythritol tetrakis (3-mercaptopropionate) and PEG and contained free thiol groups mimicking those found in natural mucosa. The other hydrogel was formed by UV (ultraviolet) curing of PEGDA and mimicked the mechanical property of mucosa but not its chemical constitute. When ranking different first generation mucoadhesive polymers using a tensile assay, both hydrogels showed good agreement with the ranking achieved for porcine small intestine. However, only PEGDA-QT and porcine small intestine shared a similar displacement curve. The same ranking for PEGDA-QT and porcine small intestine was also observed when comparing a second-generation mucoadhesive polymer, thiolated alginate, to native alginate. Our findings suggest that PEGDA-QT could serve as a replacement for porcine small intestine in both mucoadhesion evaluations using a tensile machine and the flow-through method for first and second-generation mucoadhesive polymers.

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.

Mucoadhesive vs. mucopenetrating particulate drug delivery

Mucus layer is a hydrophilic absorption barrier found in various regions of the body. The use of particulate delivery systems showed potential in drug delivery to mucosal membranes by either prolonging drug residence time at the absorption or target membrane or promoting permeation of particles across mucus gel layer to directly reach underlying epithelium. Mucoadhesive particles (MAP) are advantageous for delivering drug molecules to various mucosal membranes including eyes, oral cavity, bladder and vagina by prolonging drug residence time on those membranes. In contrast, a broader particle distribution and deeper penetration of the mucus gel layer are accomplished by mucopenetrating particles (MPP) especially in the gastrointestinal tract. Based on the available literature in particular dealing with in vivo results none of both systems (MAP and MPP) seems to be advantageous over the other. The choice of system primarily depends on the therapeutic target and peculiar properties of the target mucosa including thickness of the mucus gel layer, mucus turnover rate and water movement within the mucus. Future trends are heading in the direction of combining both systems to one i.e. mucoadhesive and mucopenetrating properties on the same particles.

The synthetic antimicrobial peptide pexiganan and its nanoparticles (PNPs) exhibit the anti-helicobacter pylori activity in vitro and in vivo

The aim of this study was to probe the potential anti-H. pylori activity of the synthetic antimicrobial peptide pexiganan, which is an analog of the peptide magainin, and its nanoparticles (PNPs) that were prepared in our laboratory. To compare their antibacterial effects in vitro and in vivo, studies of H. pylori growth inhibition, kinetics and resistance assays were undertaken. The gastric mucoadhesive efficiency and H. pylori clearance efficiency of pexiganan and PNPs were evaluated in rats and mice infected with H. pylori. The eradication of H. pylori was determined using urease tests and a microbial culture method. We observed that PNPs adhered to gastric mucosa more effectively owing to a prolonged stay in the stomach, which resulted in a more effective H. pylori clearance. In addition, PNPs had greater anti-H. pylori effect than pexiganan in infected mice. The amount of pexiganan required to eradicate H. pylori was significantly less using PNPs than the corresponding pexiganan suspension. The results confirmed that PNPs improved peptide stability in the stomach and more effectively eradicated H. pylori from mice stomachs than pexiganan.

In-vitro and in-vivo evaluation of repaglinide loaded floating microspheres prepared from different viscosity grades of HPMC polymer

During the study repaglinide encapsulated floating microspheres were formulated and characterized for enhancing residence time of drug in git and thereby increasing its bioavailability. Floating microspheres of ethylcellulose (EC) and hydroxypropyl methyl cellulose (HPMC) (5 and 100 cps) were prepared by emulsion solvent diffusion technique. During process optimization various parameters were studied such as: drug: polymer ratio, polymer ratio, concentration of emulsifier and stirring speed. Selected optimized formulations were studied for SEM, entrapment, floating behavior, drug release and kinetics. In-vivo floating ability (X-ray) study and in-vivo antidiabetic activity were performed on alloxan induced diabetic rats. Microspheres prepared with different viscosity grade HPMC were spherical shaped with smooth surface. Size of microspheres was in the range of 181.1–248 μm. Good entrapment and buoyancy were observed for 12 h. X-ray image showed that optimized formulation remained buoyant for more than 6 h. Optimized formulation treated group shows significant (p < 0.01) reduction in blood glucose level as compared to pure drug treated group. Repaglinide loaded floating microspheres expected to give new choice for safe, economical and increased bioavailable formulation for effective management of NIDDM.

Effectiveness of submicronized chitosan-coated liposomes in oral absorption of indomethacin

The plasma profile of indomethacin (IMC) after oral administration of IMC-loaded submicronized chitosan-coated liposomes (ssCS-Lip) was evaluated to reveal the effectiveness of the mucoadhesive function for improving the absorption of this poorly absorbable drug. The stomach and small intestine were removed from rats after 1, 2, and 4 hours of oral administration of submicron-sized liposomes (ssLip) or ssCS-Lip containing fluorescent dye, and the retentive properties were confirmed by measuring the amount of dye in each part of the gastrointestinal (GI) tract. Results showed that ssCS-Lip tended to be better retained in the upper part of the GI tract, compared with ssLip, at 1, 2, and 4 hours after administration, and was significantly better retained in the small intestine at 4 hours. The plasma profile and bioavailability of IMC after oral administration of both types of liposomes were improved, compared with oral administration of IMC solution. The maximum residence time of ssCS-Lip was significantly longer than those of ssLip. The extended plasma profile of ssCS-Lip was attributed to its prolonged retention in the upper region of the GI tract, and its delayed migration to the lower part of the intestine, the neutral pH of which is more soluble for IMC, an acidic drug. Therefore, the chitosan-coated ssLip, with its higher retention in the GI tract, is a promising drug carrier for the oral administration of poorly absorbed compounds.

Eradication of Helicobacter pylori: Past, present and future

Helicobacter pylori is the major cause of chronic gastritis and peptic ulcers. Since the classification as a group 1 carcinogenic by International Agency for Research on Cancer, the importance of the complete H. pylori eradication has obtained a novel meaning. Hence, several studies have been made in order to deepen the knowledge in therapy strategies. However, the current therapy presents unsatisfactory eradication rates due to the lack of therapeutic compliance, antibiotic resistance, the degradation of antibiotics at gastric pH and their insufficient residence time in the stomach. Novel approaches have been made in order to overcome these limitations. The purpose of this review is to provide an overview about the current therapy and its limitations, while highlighting the possibility of using micro- and nanotechnology to develop gastric drug delivery systems, overcoming these difficulties in the future.

Innovative pharmaceutical development based on unique properties of nanoscale delivery formulation

The advent of nanotechnology has reignited interest in the field of pharmaceutical science for the development of nanomedicine. Nanomedicinal formulations are nanometer-sized carrier materials designed for increasing the drug tissue bioavailability, thereby improving the treatment of systemically applied chemotherapeutic drugs. Nanomedicine is a new approach to deliver the pharmaceuticals through different routes of administration with safer and more effective therapies compared to conventional methods. To date, various kinds of nanomaterials have been developed over the years to make delivery systems more effective for the treatment of various diseases. Even though nanomaterials have significant advantages due to their unique nanoscale properties, there are still significant challenges in the improvement and development of nanoformulations with composites and other materials. Here in this review, we highlight the nanomedicinal formulations aiming to improve the balance between the efficacy and the toxicity of therapeutic interventions through different routes of administration and how to design nanomedicine for safer and more effective ways to improve the treatment quality. We also emphasize the environmental and health prospects of nanomaterials for human health care.

Oral delivery of peptides and proteins using lipid-based drug delivery systems

INTRODUCTION

In order to successfully develop lipid-based drug delivery systems (DDS) for oral administration of peptides and proteins, it is important to gain an understanding of the colloid structures formed by these DDS, the mode of peptide and protein incorporation as well as the mechanism by which intestinal absorption of peptides and proteins is promoted.

AREAS COVERED

The present paper reviews the literature on lipid-based DDS, employed for oral delivery of peptides and proteins and highlights the mechanisms by which the different lipid-based carriers are expected to overcome the two most important barriers (extensive enzymatic degradation and poor transmucosal permeability). This paper also gives a clear-cut idea about advantages and drawbacks of using different lipidic colloidal carriers ((micro)emulsions, solid lipid core particles and liposomes) for oral delivery of peptides and proteins.

EXPERT OPINION

Lipid-based DDS are safe and suitable for oral delivery of peptides and proteins. Significant progress has been made in this area with several technologies on clinical trials. However, a better understanding of the mechanism of action in vivo is needed in order to improve the design and development of lipid-based DDS with the desired bioavailability and therapeutic profile.

Comparison of in vitro methods of measuring mucoadhesion: ellipsometry, tensile strength and rheological measurements

In this work three in vitro methods for the measurement of mucoadhesion have been compared: ellipsometry, tensile strength and rheology. The conditions used for the three methods have been as similar as possible. Six different polymers were investigated: sodium carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), chitosan, polyvinyl pyrrolidone (PVP) and two cross-linked polyacrylic acids, Noveon (hydrophobically modified) and Carbopol. The results showed that PVP did not exhibit mucoadhesion according to any of the methods used. Chitosan, Noveon, Carbopol, CMC and HEC showed good mucoadhesion in the tensile strength and the rheological measurements, but not in the ellipsometry investigation. Chitosan was the only polymer showing good mucoadhesion with the ellipsometry method. No two methods gave the same ranking of mucoadhesive strength of the polymers. The conflicting results obtained with the different methods underline the need for further improvements in existing experimental techniques and theoretical concepts for the correct assessment of mucoadhesive properties.

Preparation and in vitro Characterization of Porous Carrier-Based Glipizide Floating Microspheres for Gastric Delivery

Floating microspheres have been utilized to obtain prolonged and uniform release of drug in the stomach for development of once-daily formulations. A controlled-release system designed to increase residence time in the stomach without contact with the mucosa was achieved through the preparation of floating microspheres by the emulsion solvent diffusion technique, using (i) calcium silicate (CS) as porous carrier; (ii) glipizide, an oral hypoglycemic agent; and (iii) Eudragit^® S as polymer. The effects of various formulations and process variables on the internal and external particle morphology, micromeritic properties, in vitro floating behavior, drug loading, and in vitro drug release were studied. The microspheres were found to be regular in shape and highly porous. The prepared microspheres exhibited prolonged drug release (~8 h) and remained buoyant for >10 h. The mean particle size increased and the drug release rate decreased at higher polymer concentrations. No significant effect of the stirring rate during preparation on drug release was observed. In vitro studies demonstrated diffusion-controlled drug release from the microspheres. Microsphere formulation CS4, containing 200 mg calcium silicate, showed the best floating ability (88% buoyancy) in simulated gastric fluid. The release pattern of glipizide in simulated gastric fluid from all floating microspheres followed the Higuchi matrix model and the Peppas-Korsmeyer model.

Gastroretentive microparticles for drug delivery applications

Many strategies have been proposed to explore the possibility of exploiting gastroretention for drug delivery. Such systems would be useful for local delivery, for drugs that are poorly soluble at higher pH or primarily absorbed from the proximal small intestine. Generally, the requirements of such strategies are that the vehicle maintains controlled drug release and exhibits prolonged residence time in the stomach. Despite widespread reporting of technologies, many have an inherent drawback of variability in transit times. Microparticulate systems, capable of distributing widely through the gastrointestinal tract, can potentially minimise this variation. While being retained in the stomach, the drug content is released slowly at a desired rate, resulting in reduced fluctuations in drug levels. This review summarises the promising role of microencapsulation in this field, exploring both floating and mucoadhesive microparticles and their application in the treatment of Helicobacter pylori, highlighting the clinical potential of eradication of this widespread infection.

Engineering strategies to enhance nanoparticle-mediated oral delivery

Oral delivery is the most preferred route of drug administration due to convenience, patient compliance and cost-effectiveness. Despite these advantages it remains difficult to achieve satisfactory bioavailability levels via oral administration due to the harsh environment of the gastrointestinal (GI) tract, particularly for biomacromolecules. One promising method to increase the bioavailability of macromolecular drugs such as proteins and nucleic acids is to encapsulate them in nanoparticles before oral administration. This review describes innovative strategies for increasing the efficacy of nanoparticle-mediated delivery to the GI tract. Approaches to optimize nanoparticle formulation by exploiting mucoadhesion, environmental responsiveness and external delivery control mechanisms are discussed. The application of recent advances in nanoparticle synthesis using supercritical fluids, microfluidics and imprint lithography to oral delivery are also presented, as well as possible strategies for incorporating nanoparticles into micro- and macroscale oral delivery devices.

Formulation and evaluation of clarithromycin microspheres for eradication of Helicobacter pylori

The objective of the study was to develop a stomach-specific drug delivery system for controlled release of clarithromycin for eradication of Helicobacter pylori (H. pylori). Floating-bioadhesive microspheres of clarithromycin (FBMC) were prepared by emulsification-solvent evaporation method using ethylcellulose as matrix polymer and Carbopol 934P as mucoadhesive polymer. The prepared microspheres were subjected to evaluation for particle size, incorporation efficiency, in vitro buoyancy, in vitro mucoadhesion and in vitro drug release characteristics. The prepared microspheres showed a strong mucoadhesive property with good buoyancy. The formulation variables like polymer concentration and drug concentration influenced the in vitro drug release significantly in simulated gastric fluid (pH. 2.0). The in vivo H. pylori clearance efficiency of prepared FBMC in reference to clarithromycin suspension following repeated oral administration to H. pylori infected Mongolian gerbils was examined by polymerase chain reaction (PCR) technique and by a microbial culture method. The FBMC showed a significant anti-H. pylori effect in the in vivo gerbil model. It was also noted that the required amount of clarithromycin for eradication of H. pylori was significantly less in FBMC than from corresponding clarithromycin suspension. The results further substantiated that FBMC improved the gastric stability of clarithromycin (due to entrapment within the microsphere) and eradicated H. pylori from the gastrointestinal tract more effectively than clarithromycin suspension because of the prolonged gastrointestinal residence time of the formulation.

Development and characterization of floating microballoons for oral delivery of cinnarizine by a factorial design

Cinnarizine (CN) is a pipperazine derivative with anti-histaminic activity and high affinity to H(1) receptors. The objective of this study was to produce floating microspheres (FM) of CN by diffusion solvent evaporation technique to increase drug solubility and hence its bioavailability. The effect of process variables such as: Eudragit type, stirring rate and time of stirring after addition of oily phase to the aqueous phase were evaluated on the yield, particle size, loading, release and floating behaviors of microspheres using a factorial design. Release of CN from microspheres was studied in pHs: 1.2 and 7.2 using paddle technique. The samples of dissolution test were analysed spectrophotometrically at 256.1 nm and 256.5 nm respectively. particle size of microspheres was studied using microscopic method and their floating behavior was studied in HCl (0.1 N, pH 1.2) medium with Tween 20 (0.5% w/v). Eight formulations were produced by changing 3 variables each at 2 levels: Eudragit S100 (Ps) or a combination of two Eudragits S100:RLPO (1:3) (P(SR)), stirring rate of 200 (R(2)) or 300 rpm (R(3)) and stirring time after addition of oily phase to the aqueous phase 0 (T(0)) or 1 hr (T(1)). The average size of microspheres was 300 microm. The highest yield efficiency (94%) was seen in P(SR)R(3)T(0) formulation and the greatest loading percentage was 8.5% in P(SR)R(2)T(1) formulation. The microspheres containing just Eudragit S100, didn't show suitable releasing profile during 8 hours in pH 1.2 but those containing combination of Eudragit S100:RL released approximately whole amount of CN during 10 hours (8 hours in pH 1.2 and 2 hours in pH 7.2). The highest floating percentage up to 6 hours was 77.5% in P(S)R(2)T(1) formulation. The type of Eudragit used seems to play an important role in producing sustained release floating microspheres. P(SR)R(3)T(0) formulation containing both types of Eudragit S100:RL (1.3) that releases 99.1% of the drug after 10 hours and 65% floating after 6 hr seems suitable for oral sustained delivery of CN.

In vitro and in vivo evaluation of mucoadhensiveness of chitosan/cellulose acetate multimicrospheres

Chitosan/cellulose acetate multimicrospheres (CCAM) with or without ranitidine (RT) were prepared by the method of W/O/W emulsion with no toxic reagents and had the size interval of 200-280 microm. The angles of repose were only a little more than 30 degrees and the maximum angles of one-plane-critical-stability (OPCS phi) were about 20 degrees . The CCAM had good suspension ability for the tapped density of CCAM was less than 0.127g/mL. The pH value affected the swelling ability of CCAM and the relative humidity had little effect on the characteristics of CCAM when it was not more than 75%. The CCAM system had good effect on the controlled release of RT in vitro and the release rate was almost 60% during 48 h. Furthermore the release of RT was not affected by pH value of release medium. The mucoadhesive tests showed that CCAM could retain in gastrointestinal tract for an extended period of time. There were 53.7% of CCAM remained in stomach after administered for 2(1/2) h and 98.9% of CCAM remained in stomach and small intestine after administered for 3(1/2) h. These results suggest that CCAM is a useful dosage form targeting the gastric mucosa or prolonging gastric residence time as a multiple-unit mucoadhesive system.