In-vivo evaluation in rats of colon-specific microspheres containing 5-fluorouracil

Carbohydrate Polymer-Based Targeted Pharmaceutical Formulations for Colorectal Cancer: Systematic Review of the Literature

Colon cancer is the third most diagnosed cancer worldwide, followed by lung and breast cancer. Conventional treatment methods are associated with numerous side effects and compliance issues. Thus, colon targeted drug delivery has gained much attention due to its evident advantages. Although many technologies have been explored, the use of pH-sensitive polymers, especially biodegradable polymers, holds exceptional promise. This review aims to collate research articles concerning recent advances in this area. A systematic search using multiple databases (Google Scholar, EMBASE, PubMed, MEDLINE and Scopus) was carried out following the preferred reported items for systematic reviews and meta-analyses (PRISMA) guidelines with an aim to explore the use of pH-sensitive carbohydrate polymers in developing colon targeted pharmaceutical formulations. Following screening and quality assessment for eligibility, 42 studies were included, exploring either single or a combination of carbohydrate polymers to develop targeted formulations for colon cancer therapy. Pectin (11) is the most widely used of these biopolymers, followed by chitosan (09), alginate (09) and guar gum (08). This systematic review has successfully gathered experimental evidence highlighting the importance of employing carbohydrate polymers in developing targeting formulations to manage colon cancer.

Eudragit-Coated Sporopollenin Exine Microcapsules (SEMC) of Phoenix dactylifera L. of 5-Fluorouracil for Colon-Specific Drug Delivery

In this study, 5-fluorouracil (5-FU)-loaded pollens of Phoenix dactylifera and their coating with ERS was done and evaluated for the colon-targeted delivery of 5-FU to treat colon cancer. Sporopollenin exine microcapsules (SEMC) from the pollens of Phoenix dactylifera were extracted by the reflux method and 5-FU into SEMC was encapsulated by the vacuum-assisted loading method. 5-FU loaded SEMC was coated with Eudragit^® RS-100 (ERS) by the organic solvent-evaporation technique under vacuum to avoid the discharge of 5-FU in the stomach and small intestine. Morphological and physicochemical characterization of drug-loaded SEMC (coated/uncoated) was performed by scanning electron microscopy (SEM), FTIR, XRD, and DSC. The encapsulation and drug loading were determined by the direct method, and an in vitro release study was performed in simulated gastric and intestinal fluids (SGF/SIF). The colon-specific delivery of 5-FU from the SEMC was assessed in terms of pharmacokinetics and gastrointestinal tract distribution after oral administration in rats. The successful encapsulation and loading of 5-FU into SEMC by a vacuum-assisted loading technique and its coating with ERS by a solvent-evaporation technique were achieved. SEM images of uncoated SEMC have shown porous structures, and coating with ERS reserved their morphology with a smooth surface and discrete microstructures and the 5% w/v ERS acetone solution. ERS-coated SEMC sustained the release of 5-FU until 24 h in SIF, while it was up to 12 h only from uncoated SEMC. The maximum plasma concentration (Cmax) of 5-FU from uncoated SEMC was 102.82 μg/mL after 1 h, indicating a rapid release of 5-FU in the upper gastrointestinal tract. This concentration decreased quickly with a half-life of 4 h, AUC0-t was 264.1 μg/mL.h, and MRT0-inf was 5.2 h. The Cmax of 5-FU from ERS-coated SEMC was 19.47 μg/mL at 16 h. The Cmax of 5-FU in small intestines was 406.2 μg/g at 1 h from uncoated SEMC and 1271.5 μg/g at 12 h from coated SEMC. Conclusively, a 249.9-fold higher relative bioavailability of 5-FU was achieved with the ERS-coated SEMC in colon tissues than that from uncoated SEMC.

Pectin co-functionalized dual layered solid lipid nanoparticle made by soluble curcumin for the targeted potential treatment of colorectal cancer

The investigation is to increase the cytotoxicity of soluble curcumin (SC) by loading it onto pectin and skimmed milk powder (SMP) dual layered solid lipid nanoparticles (DL-SLN). The DL-SLN exhibited significantly higher encapsulation efficiency (83.94 ± 6.16), better stability (90 days), and sustained the drug release in different gastro intestional (GI) environments upto 72 h. Molecular docking revealed that the Vander Waals (57420.669 Kcal^-mol^-1) and electrostatic (-197.533) bonds were involved in the DL-SLN complex formation. The in vivo toxicity of DL-SLN was performed by the zebrafish model, the cell cycle arrest at G₂/M phase (64.34 %) by flow cytometry, and western blot investigation was recognized molecular level cell death using SW480 cells. Pharmacokinetic (PK) evaluation (Cmax-5.78 ± 3.26 μg/mL; Tmax-24 h) and organ distribution studies confirmed that the co-functionalized pectin based SLN could efficiently improve the oral bioavailability (up to 72 h) of curcumin (CMN) on colon-targeted release.

In vitro and in vivo evaluation of colon cancer targeted epichlorohydrin crosslinked Portulaca-alginate beads

The aim of this study was to formulate a novel dual crosslinked hydrogel bead using Portulaca mucilage for colon-targeted delivery of 5-fluorouracil (5-FU) and evaluate its safety, specificity and efficacy. The ionotropic gelation technique was employed to prepare the hydrogel beads of Portulaca mucilage. For this, the mucilage was initially crosslinked with alginate and calcium ions. Epichlorohydrin was employed as a crosslinker in the second crosslinking step. The formulation was subjected to in vitro and in vivo studies to evaluate morphology, size, cytotoxicity, and organ distribution. Human HT-29 colon cancer cell-line was used for in vitro assays and in vivo studies were performed in Wistar rats to assess the usefulness and effectiveness of the formulation for colon cancer therapy. Microsphere sizes ranged from 930 to 977μm and possessed a high level of drug encapsulation efficiency (ca. 78% w/w). Compared with 5-FU solution (Tmax = 1.2 h, mean resident time: MRT = 3.3h) the dual crosslinked Portulaca microspheres exhibited sustained drug release after oral administration to rats (Tmax = 16h, MRT = 14h). The relative bioavailability of 5-FU solution and the microspheres were 100 and 93.6% respectively. Tissue distribution studies indicated high concentration of 5-FU in colon. In-vitro anticancer assay demonstrated IC50 value of 11.50 μg/ml against HT-29 colon cancer cell line. The epichlorohydrin cross-linked Portulaca microspheres prepared in this study provided sustained release of 5-FU up to 16h in the colonic region and enhanced the antitumor activity of the neoplastic drug. The formulation is hence an ideal carrier system for colon-targeted drug delivery.

Colon targeted curcumin microspheres laden with ascorbic acid for bioavailability enhancement

An objective of the present study was to prepare colon-specific microspheres of curcumin (CUR) containing ascorbic acid (AA) for improved oral bioavailability. 3² factorial design was used to optimise chitosan microspheres (CSMS) containing CUR and AA. Subsequently, optimised CSMS were coated with Eudragit S-100, for delivery to colon. In vitro drug release, in vivo pharmacokinetics, and organ distribution studies were performed in Albino Wistar rats. Stabilisation of CUR in alkaline pH was successfully guarded by AA to the extent 98.5-100%. Results revealed complete amorphisation/molecular dispersion of CUR. Bioavailability enhancement of CUR and 90% of MS in colon at the end of 8 h in animals, deciphered successful design of colon-specific CUR MS. It can be concluded that AA in MS shielded the degradation of CUR. The developed double coat MS could be considered as a promising colon-targeted system for CUR aiming bioavailability enhancements.

Colon targeted beads loaded with pterostilbene: Formulation, optimization, characterization and in vivo evaluation

Background

Pterostilbene has a proven chemopreventive effect for colon carcinogenesis but suffers low bioavailability limitations and therefore unable to reach the colonic tissue.

Objective and methodology

To overcome the issue of low bioavailability, pterostilbene was formulated into an oral colon targeted beads by ionic gelation method using pectin and zinc acetate. Optimization was carried out by 2³ factorial design whereby the effect of pectin concentration (X₁), zinc acetate concentration (X₂) and pterostilbene:pectin ratio (X₃) were studied on entrapment efficiency (Y₁) and in vitro drug release till 24 h (Y₂). The optimized beads were characterized for shape and size, swelling and surface morphology. The optimized beads were uniformly coated with Eudragit S-100 using fluidized bed coater. Optimized coated beads were characterized for in vitro drug release till 24 h and surface morphology. Pharmacokinetic and organ distribution study were performed in rats to ascertain the release of pterostilbene in colon.

Results

The optimized formulation comprised of 2% w/v of pectin concentration (X₁), 2% w/v of zinc acetate concentration (X₂) and 1:4 of pterostilbene:pectin ratio (X₃), which showed a satisfactory entrapment efficiency (64.80%) and in vitro release (37.88%) till 24 h. The zinc pectinate beads exhibited sphericity, uniform size distribution, adequate swelling and rough surface. The optimized coated beads achieved 15% weight gain, displayed smooth surface and optimum drug release. Pterostilbene from optimized coated beads appeared in the plasma at 14 h and reached the C_max at 22 h (T_max), whereas plain pterostilbene exhibited T_max of 3 h.

Discussion and conclusion

Thus, larger distribution of pterostilbene was obtained in the colonic tissue compared to stomach and small intestinal tissues. Thus, delayed T_max and larger distribution of pterostilbene in colonic tissue confirmed the targeting of beads to colon.

Pressure responsive nanogel base on Alginate-Cyclodextrin with enhanced apoptosis mechanism for colon cancer delivery

5-Fluorouracil (5-Fu) commonly use in the treatment of different kinds of cancer, but limited cellular uptake and death is still a problem. Herein, we report a simple process for the synthesis of pressure-sensitive nanogels that indicate to be appropriate in the delivery of 5-Fu. The hydrogels (Al-CD) prepare by crosslinking of alginate (Al) with modified beta Cyclodextrin (β-CD) as Crosslinker. Next, nanoparticles obtaine by an emulsification method. 5-Fu as model drug loades into the Al-CD nanogels easily by mixing it in aqueous solution with the nanoparticles. The results revealed that the Al-CD nanogels are cytocompatible. They have also a noticeable drug encapsulation (82.1 ±5.7%) while they can release (in vitro controlled) 5-Fu in conditions that imitate the intravascular pressure conditions. These nanogels can rapidly be taken up by HT-29 cells (a colon cell line). In addition, a higher 5-Fu intracellular accumulation and a significant cell death extension by apoptosis mechanism is notice when compare with free 5-Fu. Accordingly, the developed nanogels can be employe as an excellent candidate to overcome the inefficiency of 5-Fu in anticancer treatments and possibly can employe for further evaluation as a chemotherapical agent in applications beyond cancer. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 349-359, 2018.

Insight to drug delivery aspects for colorectal cancer

Colorectal cancer (CRC) is the third most common cancer diagnosed worldwide in human beings. Surgery, chemotherapy, radiotherapy and targeted therapies are the conventional four approaches which are currently used for the treatment of CRC. The site specific delivery of chemotherapeutics to their site of action would increase effectiveness with reducing side effects. Targeted oral drug delivery systems based on polysaccharides are being investigated to target and deliver chemotherapeutic and chemopreventive agents directly to colon and rectum. Site-specific drug delivery to colon increases its concentration at the target site, and thus requires a lower dose and hence abridged side effects. Some novel therapies are also briefly discussed in article such as receptor (epidermal growth factor receptor, folate receptor, wheat germ agglutinin, VEGF receptor, hyaluronic acid receptor) based targeting therapy; colon targeted proapoptotic anticancer drug delivery system, gene therapy. Even though good treatment options are available for CRC, the ultimate therapeutic approach is to avert the incidence of CRC. It was also found that CRCs could be prevented by diet and nutrition such as calcium, vitamin D, curcumin, quercetin and fish oil supplements. Immunotherapy and vaccination are used nowadays which are showing better results against CRC.

In vitro cytotoxicity and in vivo efficacy of 5-fluorouracil-loaded enteric-coated PEG-cross-linked chitosan microspheres in colorectal cancer therapy in rats

PURPOSE

Microspheres of chitosan (CS) cross-linked with polyethylene glycol (PEG) were prepared by emulsion-cross-linking followed by the solvent evaporation technique. The formulations were characterized and subjected to in vitro and in vivo tests to assess cell growth, changes in cell morphology, and activities by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on human HT-29 colon cancer cell-lines.

METHODS

In vivo activity was evaluated for dimethyl hydrazine-induced colorectal cancer in albino male Wistar rats. Biochemical and histological parameters were evaluated to understand their effectiveness for colon cancer therapy.

RESULTS

The 5-FU immediate release (IR) formulations suspended in SCMC produced an immediate cytotoxic effect, whereas microspheres inhibited proliferation of tumor cells to induce apoptosis over an extended time. Minimum inhibitory concentration (IC₅₀) values for both standard plain 5-FU and 5-FU-loaded microspheres were respectively 5.00 ± 0.004 µg/mL and 165 ± 1.9 µg/mL which showed the improved safety profile of the microsphere formulation. Tissue distribution showed high concentration of 5-FU in colon that was higher than IC₅₀ value required to stop the growth or death of colon cancer cells from the colonic dysplasia in Duke's stage A. Significant reduction in tumor volume and multiplicity was observed with increased levels of liver enzymes in animals when treated with standard 5-FU formulation compared with 5-FU loaded microspheres. Elevated levels of serum albumin, creatinine, leukocytopenia, and thrombocytopenia were observed in animals for the standard 5-FU formulation.

CONCLUSION

The PEG cross-linked CS microspheres of this study slowly released 5-FU up to 24 h to colonic region and enhanced the antitumor activity.

In vitro cytotoxicity and in vivo efficacy of 5-fluorouracil-loaded enteric-coated PEG-crosslinked chitosan microspheres in colorectal cancer therapy in rats

PURPOSE

Microspheres of chitosan (CS) crosslinked with polyethylene glycol (PEG) were prepared by emulsion crosslinking followed by solvent evaporation technique. The formulations were characterized and subjected to in vitro and in vivo tests to assess cell growth, changes in cell morphology and activities by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on human HT-29 colon cancer cell lines.

METHODS

In vivo activity was evaluated for dimethyl hydrazine-induced colorectal cancer in albino male Wistar rats. Biochemical and histological parameters were evaluated to understand their effectiveness for colon cancer therapy.

RESULTS

The 5-FU immediate release (IR) formulations suspended in sodium carboxymethyl cellulose (SCMC) produced an immediate cytotoxic effect, whereas microspheres inhibited the proliferation of tumor cells to induce apoptosis over an extended time. Minimum inhibitory concentration (IC50) values for both standard plain 5-FU and 5-FU-loaded microspheres were, respectively, 5.00 ± 0.004 µg/mL and 165 ± 1.9 µg/mL which showed the improved safety profile of the microsphere formulation. Tissue distribution showed high concentration of 5-FU in colon that was higher than IC50 required to stop the growth or death of colon cancer cells from the colonic dysplasia in Duke's Stage A. Significant reduction in tumor volume and multiplicity was observed with increased levels of liver enzymes in animals when treated with standard 5-FU formulation compared to 5-FU-loaded microspheres. Elevated levels of serum albumin, creatinine, leukocytopenia and thrombocytopenia were observed in animals for the standard 5-FU formulation.

CONCLUSION

The PEG-crosslinked CS microspheres of this study slowly released 5-FU up to 24 h to colonic region and enhanced the antitumor activity.

Formulation Design, Optimization and Pharmacodynamic Evaluation of Sustained Release Mucoadhesive Microcapsules of Venlafaxine HCl

The objective of present research work was to design and characterize the venlafaxine HCl-loaded sodium alginate-based mucoadhesive microcapsules by ionic gelation technique using HPMC K100M as mucoadhesive polymer. The Placket-Burman Design was applied for preliminary screening of the formulations and systematic optimization by using Box-Behnken Design. The prepared microcapsules were characterized for drug content, entrapment efficiency, micromeritic properties, particle size, swelling index, mucoadhesive strength, in vitro drug release and in vivo antidepressant activity. FTIR and differential scanning calorimetry studies showed no incompatibility. Surface morphology studies revealed spherical nature of the prepared microcapsules. In vitro drug release studies revealed sustained release by diffusion mechanism. Further, the microcapsules were effective in reducing the depression induced by forced swimming test in Sprague-Dawley rats compared to the pure drug. The microcapsules were found to be stable under accelerated stability conditions, which suggest them as better alternative delivery systems for enhanced therapeutic efficacy of antidepressant drug, venlafaxine HCl.

Eudragit-coated dextran microspheres of 5-fluorouracil for site-specific delivery to colon

Objective of the present investigation was to prepare and evaluate the potential of enteric coated dextran microspheres for colon targeting of 5-fluorouracil (5-FU). Dextran microspheres were prepared by emulsification-crosslinking method and the formulation variables studied included different molecular weights of dextran, drug:polymer ratio, volume of crosslinking agent, stirring speed and time. Enteric coating (Eudragit S-100) of dextran microspheres was performed by oil-in-oil solvent evaporation method using different coat:core ratios (4:1 or 8:1). Uncoated and coated dextran microspheres were characterized by particle size, surface morphology, entrapment efficiency, DSC, in vitro drug release in the presence of dextranase and 2% rat cecal contents. The release study of 5-FU from coated dextran microspheres was pH dependent. No release was observed at acidic pH; however, the drug was released quickly where Eudragit starts solublizing there was continuous release of drug from the microspheres. Organ distribution study was suggested that coated dextran microspheres retard the release of drug in gastric and intestinal pH environment and released of drug from microspheres in colon due to the degradation of dextran by colonic enzymes.

Pulsatile drug release from electrospun poly(ethylene oxide)–sodium alginate blend nanofibres

Novel and highly tuneable pulsatile drug release systems have been prepared by electrospinning.

A predictive biomarker for altered 5-fluorouracil pharmacokinetics following repeated administration in a rat model of colorectal cancer

The relationship between the plasma ratio of dihydrouracil/uracil (UH2/Ura) and hepatic dihydropyrimidine dehydrogenase (DPD) activity after repeated 5-fluorouracil (5-FU) treatment in rats with colorectal cancer (CRC) was investigated. Repeated intravenous 5-FU bolus injections resulted in a significant decrease in the total clearance (CLtot ) and an increased area under the curve (AUC0-∞ ) in CRC rats. Furthermore, the hepatic DPD levels and the plasma ratio of UH2/Ura decreased significantly and lost their circadian rhythms in CRC rats treated repeatedly with 5-FU, although significant circadian variation in the two parameters was observed in the control CRC rats. Moreover, a significant correlation was found between the plasma ratio of UH2/Ura and hepatic DPD activity in CRC rats untreated and treated with single or repeated 5-FU administration (r(2)  = 0.865, p < 0.01). The ratio of UH2/Ura in plasma could be a predictive biomarker of the suppression of hepatic DPD levels during repeated 5-FU-based treatment. Furthermore, by plotting the observed pharmacokinetic parameters of 5-FU against hepatic DPD activity levels predicted by the ratio of UH2/Ura in plasma, AUC0-∞ , CLtot and half-life (t1/2 ) were closely linked to predicted hepatic DPD activity levels. These observations suggest that the factor that significantly influences the AUC0-∞ , CLtot and t1/2 of 5-FU after single or repeated administration of 5-FU is the hepatic DPD activity and it could be assessed by the ratio of UH2/Ura in plasma.

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.

Preparation and in vitro/in vivo characterization of curcumin microspheres intended to treat colon cancer

OBJECTIVE

The objective of the present investigation was to prepare colon targeted curcumin microspheres using Eudragit S100 and evaluate the same for in vitro/in vivo properties.

MATERIALS AND METHODS

A "O/O solvent evaporation" technique was used in the preparation of microspheres. The influence of various process variables including stirring speed, drug:polymer ratio and percentage of emulsifier on the fabrication were investigated and the formulation was optimized. Prepared microspheres were evaluated for in vitro and in vivo properties. Surface morphology, particle size, percentage drug entrapment, percentage yield, drug polymer interaction, in vitro drug release in simulated gastrointestinal transit conditions and stability were the in vitro parameters investigated. Using an optimized formulation, drug release into the systemic circulation and organ distribution were investigated as in vivo parameters. In vivo parameters were estimated in male albino rats.

RESULTS

Curcumin microspheres of Eudragit S100 were successfully prepared using o/o solvent evaporation method. Microspheres prepared using 1:2 drug:polymer ratio, with a stirring speed of 1000 rpm, and using 1.0% w/v concentration of emulsifying agent was selected as an optimized formulation. The release studies with optimized formulation demonstrated that aqueous solubility of curcumin was enhanced by 8 times with the formulation. FTIR studies demonstrated no change in drug characteristics upon microsphere fabrication. The enhancement in solubility is thus due to the increase in the surface area of the drug substance and not due to a change of drug to a different physical state. This was further confirmed by scanning electron microsphere pictures. Drug release followed Korsmeyer and Peppas release model. Accelerated stability studies indicated that the drug is stable in the formulation for a period of atleast 14 weeks at room temperature. In vivo studies demonstrated a sustained drug release into the systemic circulation after oral administration of the formulation. Further, colon target was affectively achieved using the optimized formulation. Eudragit microspheres delivered most of their drug load (79.0%) to the colon, whereas with plain drug suspension only 28.0% of the total dose reached the target site.

CONCLUSION

This study successfully developed curcumin microspheres that can be used effectively in the treatment of the colon cancer.

Layered inorganic nanocomposites: a promising carrier for 5-fluorouracil (5-FU)

We report here the intercalation of 5-fluorouracil (5-FU), an anticancer drug in interlayer gallery of Na(+) clay (Montmorillonite, MMT), with the assistance of biopolymer (chitosan, CS). The X-ray diffraction patterns, thermal and spectroscopic analyses indicated the drug intercalation into the clay interlayer space in support of CS and stabilized in the longitudinal monolayer by electrostatic interaction. In vitro drug release showed controlled release pattern. The genotoxic effect of drug was in vitro evaluated in human lymphocyte cell culture by comet assay, and results indicated significant reduction in DNA damage when drug was intercalated with clay and formulated in composites. The results of in vitro cell viability assay in cancer cells pointed at decreased toxicity of drug when encapsulated in Na(+)-clay plates than the pristine drug. In vivo pharmacokinetics, biodistribution, hepatotoxicity markers, e.g., SGPT and SGOT, and liver/testicular histology in rats showed plasma/tissue drug levels were within therapeutic window as compared to pristine drug. Therefore, drug-clay hybrid and composites can be of considerable value in chemotherapy of cancer with reduced side effects.