Colon specific delivery of indomethacin: effect of incorporating pH sensitive polymers in xanthan gum matrix bases

Formulation and Development of Flurbiprofen Colon-Specific Eudragit Coated Matrix Tablets: Use of a Novel Crude Banana Peel Powder as a Time-Dependent Polymer

The rationale for the current investigation is to study the crude banana peel (CBP) powder efficiency as a novel natural time-dependent polymer along with a pH-sensitive polymer to develop flurbiprofen colon-specific tablets. The direct compression method is utilized to prepare the flurbiprofen-CBP matrix tablets using 9 mm punches on the rotary tableting machine and subsequently coated with Eudragit® S 100 by a dip coating method. The tablets were evaluated for various tableting properties and in vitro drug release studies. From the results of dissolution studies, the F6 formulation showed negligible drug release (5.76% in 5 h) in the upper gastrointestinal tract and progressive release in the colon (99.08% in 24 h). Mean dissolution time, T10%, and T80% were found to be 13.33 h, 5.8 h, and 20.7 h, respectively, which explains the efficiency of the present combination of polymers for colon-specific drug release. From the dissolution studies results of stability studies, the similarity index was calculated and found to be 74.75. In conclusion, utilizing CBP as a natural, time-dependent polymer in conjunction with Eudragit® S 100 to develop the flurbiprofen tablets seems like a promising approach for delivering drugs specifically to the colon.

Preclinical Pharmacokinetics and Acute Toxicity in Rats of 5-{[(2E)-3-Bromo-3-carboxyprop-2-enoyl]amino}-2-hydroxybenzoic Acid: A Novel 5-Aminosalicylic Acid Derivative with Potent Anti-Inflammatory Activity

Compound 5-{[(2E)-3-bromo-3-carboxyprop-2-enoyl]amino}-2-hydroxybenzoic acid (C1), a new 5-aminosalicylic acid (5-ASA) derivative, has proven to be an antioxidant in vitro and an anti-inflammatory agent in mice. The in vivo inhibition of myeloperoxidase was comparable to that of indomethacin. The aim of this study was to take another step in the preclinical evaluation of C1 by examining acute toxicity with the up-and-down OECD method and pharmacokinetic profiles by administration of the compound to Wistar rats through intravenous (i.v.), oral (p.o.), and intraperitoneal (i.p.) routes. According to the Globally Harmonized System, C1 belongs to categories 4 and 5 for the i.p. and p.o. routes, respectively. An RP-HPLC method for C1 quantification in plasma was successfully validated. Regarding the pharmacokinetic profile, the elimination half-life was approximately 0.9 h with a clearance of 24 mL/min after i.v. administration of C1 (50 mg/kg). After p.o. administration (50 mg/kg), the maximum plasma concentration was reached at 33 min, the oral bioavailability was about 77%, and the compound was amply distributed to all tissues evaluated. Therefore, C1 administered p.o. in rats is suitable for reaching the colon where it can exert its effect, suggesting an important advantage over 5-ASA and indomethacin in treating ulcerative colitis and Crohn’s disease.

Shellac- a natural carrier for colon targeting of indomethacin using hot melt extrusion

Indomethacin (IND) is one of the supporting drug candidates for colonic targeting but it belongs to BCS class II category presenting a challenge in optimal targeting at the colonic site. To overcome this challenge, we sought to prepare a pH-dependent soluble ternary solid dispersion (SD) of IND of improved solubility and dissolution rate at the colon without the need for a coating. The current study focuses on the preparation of binary SDs of API (IND) with shellac (SSB 55) and Eudragit FS 100 (EFS) and ternary mixtures of IND, SSB 55 together with a new grade of HPMC (A15). Respective SDs were prepared via HME to achieve gastric protection and improved dissolution performance including maintenance of supersaturation. The SDs were characterized and tested for in-vitro dissolution performance using a pH shift dissolution method from 1.1, 5.5, 6.8, and 7.4. A ternary extrudate of IND, SSB 55, and A15 showed improved protection below pH 5.5 with a complete release of 99.5% at pH 7.4 compared to IND neat and binary extrudates from IND-A15, IND-SSB 55, and IND-EFS. It was attributed to an increased level of intermolecular interaction confirmed by ATR-IR and was studied for stability. It was found that in a ternary mixture containing IND, A15 and SSB 55 an increased hydrogen bonding interaction is present, which resulted in improved dissolution performance compared to binary mixtures. Therefore, ternary SDs proved to be a promising concept for future development of colon targeting of poorly soluble drugs.

In Vitro and In Vivo Gastrointestinal Survival of Non-Encapsulated and Microencapsulated Salmonella Bacteriophages: Implications for Bacteriophage Therapy in Poultry

The therapeutic use of bacteriophages is recognized as a viable method to control Salmonella. Microencapsulation of phages in oral dosage forms may protect phages from inherent challenges of the gastrointestinal tract in chickens. Therefore, the main objective of this study was to assess the survival of Salmonella BP FGS011 (non-encapsulated and microencapsulated) through the gastrointestinal tract under in vitro as well as in vivo conditions after oral administration to 1-day-old chicks. To this end, the phage FGS011 was encapsulated in two different pH-responsive formulations with polymers Eudragit^® L100, and Eudragit^® S100 using the process of spray drying. Phages encapsulated in either of the two formulations were able to survive exposure to the proventriculus-gizzard in vitro conditions whereas free phages did not. Moreover, phages formulated in polymer Eudragit^® S100 would be better suited to deliver phage to the caeca in chickens. In the in vivo assay, no statistically significant differences were observed in the phage concentrations across the gastrointestinal tract for either the free phage or the encapsulated phage given to chicks. This suggested that the pH of the proventriculus/gizzard in young chicks is not sufficiently acidic to cause differential phage titre reductions, thereby allowing free phage survival in vivo.

A polymer-based anti-quorum catheter coating to challenge MDR Staphylococcus aureus: in vivo and in vitro approaches

BACKGROUND

MDR Staphylococcus aureus is a major aetiological agent of catheter-associated infections. A quorum sensing targeted drug development approach proves to be an effective alternative strategy to combat such infections.

METHODS

Intravenous catheters were coated with polymethacrylate copolymers loaded with the antivirulent compound 2-[(methylamino)methyl]phenol (2MAMP). The in vitro drug release profile and kinetics were established. The anti-biofilm effect of the coated catheters was tested against clinical isolates of MDR S. aureus. The in vivo studies were carried out using adult male Wistar rats by implanting coated catheters in subcutaneous pockets. Histopathological analysis was done to understand the immunological reactions induced by 2MAMP.

RESULTS

A uniform catheter coating of thickness 0.1 mm was achieved with linear sustained release of 2MAMP for 6 h. The coating formulation was cytocompatible. The in vitro and in vivo anti-adherence studies showed reduced bacterial accumulation in coated catheters after 48 h. The histopathological results confirmed that the coated catheter did not bring about any adverse inflammatory response.

CONCLUSIONS

The developed anti-quorum-coated catheter that is non-toxic and biocompatible has the potential to be used in other medical devices, thereby preventing catheter-associated infections.

Colon Targeting of Naringin for Enhanced Cytoprotection Against Indomethacin-Induced Colitis in Rabbits

Background

Naringin is a promising anti-inflammatory drug against various disorders including ulcerative colitis. However, its oral bioavailability is low (8%) possibly due to cleavage at the upper gut. Consequently, colon targeting would be necessary for drug protection at the upper gut, enhanced oral bioavailability and potentiated cytoprotection against colitis.

Methodology

This study involved the formulation of compression-coated tablets of naringin employing mixtures of pH-sensitive Eudragit L100-55 (EUD-L100-55) and different time-dependent polymers including ethyl cellulose (EC), sodium alginate (ALG) and sodium carboxymethyl cellulose (SCMC). Drug-polymer interaction during release was assessed using Fourier transform-infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). Tablets were evaluated in vitro. Surface morphology of the optimized tablets either before or after exposure to the different release media was examined employing scanning electron microscopy (SEM). Cytoprotection potential of the optimized tablets against indomethacin-induced colitis in rabbits was screened and compared to core tablets through a histopathological examination of colon, measurement of serum perinuclear antineutrophil cytoplasmic antibodies (pANCA) and immunohistochemical localization of tumor necrosis factor-alpha (TNF-α).

Results

FT-IR and DSC results may indicate drug-polymers interaction during release. Release retardation could be related to polymer swelling that was in the order of SCMC > ALG > EC. SEM examination indicated more porous coats at the buffers relative to the acidic medium. Colon targeting was expected in case of coats of 5% ALG, 5% SCMC and 10% EC (w/w) in combination with EUD-L100-55; thus, they were selected for in vivo evaluation. Effective cytoprotection of selected tablets against indomethacin-induced colitis was indicated by a significant (P<0.05) reduction in mucosal damage, serum levels of pANCA and TNF-α expression compared to untreated colitis and core-pretreated groups. Compared to EC, higher cytoprotection potential of ALG- and SCMC-based tablets was reflected by lower concentration (5% w/w) to provide cytoprotection against indomethacin-induced colitis.

New Perspective Enteric-Coated Tablet Dosage Form for Oral Administration of Ceftriaxone: In Vitro and In Vivo Assessments

Ceftriaxone (CTX) is a widely used injectable third-generation cephalosporin that exhibits broad-spectrum antibacterial activity. Unfortunately, the oral route of this drug suffers different encumbrances, such as instability in the upper part of the GIT and enzymatic degradation, as well as poor permeability. There is no reported tablet dosage form for this drug. In this respect, the authors investigated the possibility of developing an enteric-coated oral tablet of CTX that would be helpful for better patient compliance. The tablet consists of directly compressed core of CTX, citric acid (CA), sodium chloride (NaCl), and two biopolymers-chitosan (CH), a permeation enhancer, and silicified microcrystalline cellulose (SMCC), a wicking agent. Both biopolymers are naturally occurring polysaccharides that are biodegradable in the colon and able to incorporate acid labile drugs. CA is a pH modulator to protect CTX from protease enzymes, while NaCl is a translocation enhancer that helps drug penetration. The enteric coat of the core was shellac (SH) with plasticizer glycerol tristearate (GTS) and CA that was applied by direct compression (dry coating). The solventless heat curable coat resulted in an enteric-coated tablet that complies with the USP pharmacopeia. The optimized formula was further subjected to in vitro release and stability studies, as well as ingredient compatibility. In vivo oral bioavailability of the enteric-coated tablets in rabbits gave promising results (absolute bioavailability of about 80%). Synergistically, all ingredients together augmented oral bioavailability of CTX. This developed formula could be a perspective delivery system for those drugs intended to be absorbed from the colon such as peptides and peptide-like drugs.

Colonic delivery of indometacin loaded PGA-co-PDL microparticles coated with Eudragit L100-55 from fast disintegrating tablets

The aim of this work was to investigate the efficient targeting and delivery of indometacin (IND), as a model anti-inflammatory drug to the colon for treatment of inflammatory bowel disease. We prepared fast disintegrating tablets (FDT) containing IND encapsulated within poly(glycerol-adipate-co-ɷ-pentadecalactone), PGA-co-PDL, microparticles and coated with Eudragit L100-55 at different ratios (1:1.5, 1:1, 1:0.5). Microparticles encapsulated with IND were prepared using an o/w single emulsion solvent evaporation technique and coated with Eudragit L-100-55 via spray drying. The produced coated microparticles (PGA-co-PDL-IND/Eudragit) were formulated into optimised FTD using a single station press. The loading, in vitro release, permeability and transport of IND from PGA-co-PDL-IND/Eudragit microparticles was studied in Caco-2 cell lines. IND was efficiently encapsulated (570.15±4.2μg/mg) within the PGA-co-PDL microparticles. In vitro release of PGA-co-PDL-IND/Eudragit microparticles (1:1.5) showed significantly (p<0.05, ANOVA/Tukey) lower release of IND 13.70±1.6 and 56.46±3.8% compared with 1:1 (89.61±2.5, 80.13±2.6%) and 1:0.5 (39.46±0.9 & 43.38±3.12) after 3 and 43h at pH 5.5 and 6.8, respectively. The permeability and transport studies indicated IND released from PGA-co-PDL-IND/Eudragit microparticles had a lower permeability coefficient of 13.95±0.68×10^-6cm/s compared to free IND 23.06±3.56×10^-6cm/s. These results indicate the possibility of targeting anti-inflammatory drugs to the colon using FDTs containing microparticles coated with Eudragit.

A Novel Approach to Flurbiprofen Pulsatile Colonic Release: Formulation and Pharmacokinetics of Double-Compression-Coated Mini-Tablets

A significant plan is executed in the present study to study the effect of double-compression coating on flurbiprofen core mini-tablets to achieve the pulsatile colonic delivery to deliver the drug at a specific time as per the patho-physiological need of the disease that results in improved therapeutic efficacy. In this study, pulsatile double-compression-coated tablets were prepared based on time-controlled hydroxypropyl methylcellulose K100M inner compression coat and pH-sensitive Eudragit S100 outer compression coat. Then, the tablets were evaluated for both physical evaluation and drug-release studies, and to prove these results, in vivo pharmacokinetic studies in human volunteers were conducted. From the in vitro drug-release studies, F6 tablets were considered as the best formulation, which retarded the drug release in the stomach and small intestine (3.42 ± 0.12% in 5 h) and progressively released to the colon (99.78 ± 0.74% in 24 h). The release process followed zero-order release kinetics, and from the stability studies, similarity factor between dissolution data before and after storage was found to be 88.86. From the pharmacokinetic evaluation, core mini-tablets producing peak plasma concentration (C max) was 14,677.51 ± 12.16 ng/ml at 3 h T max and pulsatile colonic tablets showed C max = 12,374.67 ± 16.72 ng/ml at 12 h T max. The area under the curve for the mini and pulsatile tablets was 41,238.52 and 72,369.24 ng-h/ml, and the mean resident time was 3.43 and 10.61 h, respectively. In conclusion, development of double-compression-coated tablets is a promising way to achieve the pulsatile colonic release of flurbiprofen.

Pharmacokinetics of colon-specific pH and time-dependent flurbiprofen tablets

Present research deals with the development of compression-coated flurbiprofen colon-targeted tablets to retard the drug release in the upper gastro intestinal system, but progressively release the drug in the colon. Flurbiprofen core tablets were prepared by direct compression method and were compression coated using sodium alginate and Eudragit S100. The formulation is optimized based on the in vitro drug release study and further evaluated by X-ray imaging and pharmacokinetic studies in healthy humans for colonic delivery. The optimized formulation showed negligible drug release (4.33 ± 0.06 %) in the initial lag period followed by progressive release (100.78 ± 0.64 %) for 24 h. The X-ray imaging in human volunteers showed that the tablets reached the colon without disintegrating in the upper gastrointestinal tract. The C max of colon-targeted tablets was 12,374.67 ng/ml at T max 10 h, where as in case of immediate release tablets the C max was 15,677.52 ng/ml at T max 3 h, that signifies the ability of compression-coated tablets to target the colon. Development of compression-coated tablets using combination of time-dependent and pH-sensitive approaches was suitable to target the flurbiprofen to colon.

Rheological characterization of an acetaminophen jelly

The aim of this study was to prepare an inclusion complex of acetaminophen and β-cyclodextrin (molar ratio of 1:1). A jelly with inclusion complexes formed by kneading was prepared. The formation of inclusion complexes was assessed by powder X-ray diffraction patterns and Fourier transform-infrared spectroscopy. Jellies were prepared with xanthan gum, gelatin, and κ-carrageenan. The concentration of each jelling agent was 0.5, 1.0, and 1.5% w/v. Viscoelasticity and dissolution characteristics were determined and osmometry was performed. PGWater(™), a commercial jelly for fluid replacement, served as a reference for viscoelastic characteristics and dissolution. Powder X-ray diffraction measurement revealed a different diffraction pattern for the kneading than for acetaminophen and β-cyclodextrin. Fourier transform-infrared spectroscopy revealed an absorption peak (at around 1655 cm(-1)) due to the carbonyl group and benzene ring (at around 1610 cm(-1)) of acetaminophen. In contrast, the kneaded mixture (1:1) had a shift in the absorption peak due to the carbonyl group (at around 1650 cm(-1)) in acetaminophen's molecular structure, and the formation of an inclusion complex was noted. The viscosity of xanthan gum-1.0, gelatin-1.5, and carrageenan-0.5 resembled the viscoelasticity of PGWater(™). The acetaminophen in gelatin-1.0 and carrageenan-0.5 had dissolution behavior similar to that of commercial acetaminophen preparations. The osmolality of jellies prepared in different concentrations ranged from about 20-50 mOsm/kg. Results suggested that carrageenan-0.5 could serve as a useful jelly vehicle for acetaminophen.

Characterization of soy polysaccharide and its in vitro and in vivo evaluation for application in colon drug delivery

The objective of the present investigation was to establish potential of commercially available soy polysaccharide (Emcosoy®) for colon drug delivery. The soy polysaccharide-ethyl cellulose films were fabricated and characterized. The effect of the pectinase enzyme on the tensile strength and surface morphology of the film was evaluated. The permeation of chlorpheniramine maleate (CPM), a model hydrophilic drug from pectinase enzyme treated and untreated films was measured in pH 7.4 buffer. The soy polysaccharide-ethyl cellulose films were also incubated with Lactobacillus sp. culture for a specific duration, and effect on the CPM permeation was evaluated. The CPM capsules were coated with the soy polysaccharide-ethyl cellulose mixture, and Eudragit S100 was applied as a secondary coat. The coated CPM capsules were radiolabelled, and their in vivo transit was evaluated in human volunteers on oral administration. The pectinase enzyme had a significant influence on the tensile strength and surface morphology of the soy polysaccharide-ethyl cellulose films. The permeability of pectinase enzyme-treated and Lactobacillus sp.-treated films was significantly higher than that of untreated films. The CPM capsules were coated with the soy polysaccharide-ethyl cellulose mixture and Eudragit S100 and were successfully radiolabelled by a simple method. Gamma scintigraphic studies in human volunteers showed that the radiolabelled capsules maintained integrity for at least 9 h after oral administration. Thus, the soy polysaccharide has a potential in colon drug delivery.

Strategies of targeting oral drug delivery systems to the colon and their potential use for the treatment of colorectal cancer

Colorectal cancer (CRC) is the third most common cause of cancer-related death in both men and women. Often, surgical intervention remains the choice in treating CRC. Traditional dosage forms used for treating CRC deliver drug to wanted as well as unwanted sites of drug action resulting in several adverse side effects. Targeted oral drug delivery systems are being investigated to target and deliver chemotherapeutic and chemopreventive agents directly to colon and rectum. Site-specific delivery of a drug to colon increases its concentration at the target site, and thus requires a lower dose with reduced incidence of side effects. The major obstacle to be overcome for successful targeting of drug to colon through oral route is that drug absorption/degradation must be avoided in stomach and small intestine before the dosage form reaches colon. The review includes discussion of physiological factors that must be considered when targeting drugs directly to colorectal region, an outline on drugs used for treatment and prevention of CRC, and a brief description of various types of colon-targeted oral drug delivery systems. The focus is on the assessment of various formulation approaches being investigated for oral colon-specific delivery of drugs used in the treatment and prevention of CRC.

Influence of some formulation variables on the optimization of pH-dependent, colon-targeted, sustained-release mesalamine microspheres

The aim of this work was to understand the influence of different formulation variables on the optimization of pH-dependent, colon-targeted, sustained-release mesalamine microspheres prepared by O/O emulsion solvent evaporation method, employing pH-dependent Eudragit S and hydrophobic pH-independent ethylcellulose polymers. Formulation variables studied included concentration of Eudragit S in the internal phase and the ratios between; internal to external phase, drug to Eudragit S and Eudragit S to ethylcellulose to mesalamine. Prepared microspheres were evaluated by carrying out in vitro release studies and determination of particle size, production yield, and encapsulation efficiency. In addition, morphology of microspheres was examined using optical and scanning electron microscopy. Emulsion solvent evaporation method was found to be sensitive to the studied formulation variables. Particle size and encapsulation efficiency increased by increasing Eudragit S concentration in the internal phase, ratio of internal to external phase, and ratio of Eudragit S to the drug. Employing Eudragit S alone in preparation of the microspheres is only successful in forming acid-resistant microspheres with pulsatile release pattern at high pH. Eudragit S and ethylcellulose blend microspheres were able to control release under acidic condition and to extend drug release at high pH. The stability studies carried out at 40°C/75% RH for 6 months proved the stability of the optimized formulation. From the results of this investigation, microencapsulation of mesalamine in microspheres using blend of Eudragit S and ethylcellulose could constitute a promising approach for site-specific and controlled delivery of drug in colon.