Colonic targeting of aminosalicylates for the treatment of ulcerative colitis

Bioadhesive Tannic-Acid-Functionalized Zein Coating Achieves Engineered Colonic Delivery of IBD Therapeutics via Reservoir Microdevices

The biggest challenge in oral delivery of anti-inflammatory drugs such as 5-aminosalicylic acid (5-ASA) is to (i) prevent rapid absorption in the small intestine and (ii) achieve localized release at the site of inflammation in the lower gut, i.e., the colon. Here, we present an advanced biopolymeric coating comprising of tannic-acid-functionalized zein protein to provide a sustained, colon-targeted release profile for 5-ASA and enhance the mucoadhesion of the dosage form via a mussel-inspired mechanism. To enable localized delivery and provide high local concentration, 5-ASA is loaded into the microfabricated drug carriers (microcontainers) and sealed with the developed coating. The functionality and drug release profile of the coating are characterized and optimized in vitro, showing great tunability, scalability, and stability toward proteases. Further, ex vivo experiments demonstrate that the tannic acid functionalization can significantly enhance the mucoadhesion of the coating, which is followed up by in vivo investigations on the intestinal retention, and pharmacokinetic evaluation of the 5-ASA delivery system. Results indicate that the developed coating can provide prolonged colonic delivery of 5-ASA. Therefore, the here-developed biodegradable coating can be an eco-friendly substitute to the state-of-the-art commercial counterparts for targeted delivery of 5-ASA and other small molecule drugs.

Development and application of a nanocomposite derived from crosslinked HPMC and Au nanoparticles for colon targeted drug delivery

Herein, we report a novel route for the synthesis of poly(acrylamide) (PAAm) crosslinked hydroxypropyl methyl cellulose/Au nanocomposite where chemically crosslinked HPMC (c-HPMC) works as a reducing agent.

A yeast-based screen reveals that sulfasalazine inhibits tetrahydrobiopterin biosynthesis

We introduce an approach for detection of drug-protein interactions that combines a new yeast three-hybrid screening for identification of interactions with affinity chromatography for their unambiguous validation. We applied the methodology to the profiling of clinically approved drugs, resulting in the identification of previously known and unknown drug-protein interactions. In particular, we were able to identify off-targets for erlotinib and atorvastatin, as well as an enzyme target for the anti-inflammatory drug sulfasalazine. We demonstrate that sulfasalazine and its metabolites, sulfapyridine and mesalamine, are inhibitors of the enzyme catalyzing the final step in the biosynthesis of the cofactor tetrahydrobiopterin. The interference with tetrahydrobiopterin metabolism provides an explanation for some of the beneficial and deleterious properties of sulfasalazine and furthermore suggests new and improved therapies for the drug. This work thus establishes a powerful approach for drug profiling and provides new insights in the mechanism of action of clinically approved drugs.

Non-coated multiparticulate matrix systems for colon targeting

BACKGROUND

Colon specific drug delivery can significantly improve the efficacy of local treatments of inflammatory bowel diseases. Film coatings containing the starch derivative Nutriose have recently been reported to minimize 5-ASA release in media simulating the upper gastro intestinal tract (GIT), while releasing the drug in a time-controlled manner upon contact with feces from Crohn's Disease and Ulcerative Colitis patients. It was the aim of this study to prepare Nutriose-containing matrix pellets and mini tablets in order to avoid a film coating step.

METHODS

Highly dosed matrix pellets were prepared by extrusion-spheronization, highly dosed mini tablets by compression. Various types of lipids were added and drug release measured in 0.1 N HCl and phosphate buffer pH 6.8, optionally containing pepsin and pancreatin.

RESULTS

The type of added lipid and the preparation technique, in particular the curing conditions, significantly affected the resulting drug release kinetics. Glyceryl palmitostearate containing pellets and mini tablets showed the most promising results upon appropriate curing, minimizing premature drug release in media simulating the upper GIT.

CONCLUSION

The proposed novel multiparticulates do not require a film coating step and show an interesting potential for site-specific drug delivery to the colon of inflammatory bowel disease patients.

The targeting of surface modified silica nanoparticles to inflamed tissue in experimental colitis

One aspect in the emerging field of nanomedicine is site specific drug delivery via nanoparticles. The use of nanoparticles allows for increased therapeutic efficiency with a lowered risk for and extent of adverse reactions resulting from systemic drug absorption. 5-Amino salicylic acid (5ASA) loaded silica nanoparticles (SiNP) are proposed here as drug delivery system for specific accumulation in inflamed colonic tissues allowing for selective medication delivery to such inflammation sites. The drug was covalently bound to SiNP by a four-step reaction process. In-vitro toxicity of modified SiNP was tested in appropriate cell culture systems, while targeting index and therapeutic efficiency were evaluated in a pre-existing colitis in mice. Particle diameter was around 140 nm after final surface modification. In-vitro drug release demonstrated significant drug retention inside the NP formulation. Toxicity of the different formulations was evaluated in-vitro cell culture exhibiting a lowered toxicity for 5ASA when bound to SiNP. In-vivo, oral SiNP were found to accumulate selectively in the inflamed tissues allowing for significant amounts of drug load. SiNP demonstrated their therapeutic potential by significantly lowering the therapeutically necessary drug dose when evaluating clinical activity score and myeloperoxidase activity (untreated control: 28.0+/-5.0 U/mg; 5ASA-solution (100mg/kg): 8.2+/-3.4 U/mg 5ASA-SiNP (25mg/kg): 5.2+/-2.4 U/mg). SiNP allow to combine advantages from selective drug targeting and prodrugs appearing to be a promising therapeutic approach for clinical testing in the therapy of inflammatory bowel disease.

Effect of mesalazine on epithelial cell proliferation in colonic diverticular disease

BACKGROUND AND AIMS

Increased epithelial cell proliferation may be detected in diverticular disease, but antibiotics have failed in reducing it. We assess therefore the effect of mesalazine on epithelial cell proliferation in diverticular disease.

METHODS

A prospective study was conducted on 20 consecutive patients with a new endoscopic diagnosis of symptomatic uncomplicated diverticular disease. The patients were treated with mesalazine 1.6 mg/day for 1 year. The Ki-67 antigen index of the whole crypt and in the upper third was separately evaluated before and after starting the treatment.

RESULTS

Cell proliferation index was higher in diverticular disease patients than healthy controls both in the whole crypt (median 6.7%, range 2-9% vs. median 1.6%, range 1-3%, p=0.001) and in the upper third of the crypt (median 6.8%, range 2-8% vs. median 1.8%, range 1-3%, p=0.001). Cell proliferation decreased throughout the follow-up. In the whole crypt it was 6.7% at entry and 3.8% at the end of treatment (p<0.005), whereas it was 6.8% at entry and 2.9% at the end of treatment in the upper third of the crypt (p<0.005).

CONCLUSIONS

We found mesalazine effective in reducing the colonic cell proliferation in long-term treatment for colonic diverticular disease.

catena-Poly[[tetra-aqua-cobalt(II)]-μ-2,2'-dihydroxy-5,5'-diazenediyldibenzoato]

In the title compound, [Co(C(14)H(8)N(2)O(6))(H(2)O)(4)](n), each 5,5'-diazenediylbis(2-hydroxy-benzoato) ligand acts as a dicarboxyl-ate bridge, leading to the formation of polymeric chains running in the [10] direction. The Co atom is hexa-coordinated in a distorted octa-hedral geometry by six O atoms [Co-O = 2.039 (4)-2.115 (4) Å] from two ligands and four water mol-ecules. Inter-molecular O-H⋯O and O-H⋯N hydrogen bonds build up a three-dimensional supra-molecular structure.

catena-Poly[[tetra-aqua-zinc(II)]-μ-2,2'-dihydr-oxy-5,5'-diazenediyldibenzoato]

In the title compound, [Zn(C(14)H(8)N(2)O(6))(H(2)O)(4)](n), the 2,2'-dihydr-oxy-5,5'-diazenediyldibenzoate ligand acts as a carboxyl-ate bridge, leading to the formation of a polymeric chain running along the [10] direction. The Zn(II) atom is hexa-coordinated in a distorted octa-hedral geometry by six O atoms [Zn-O = 2.055 (4)-2.132 (3) Å] from two carboxylate ligands and four water mol-ecules. The crystal packing is stabilized by inter-molecular O-H⋯O, O-H⋯N and C-H⋯O hydrogen bonds, and two π-π inter-actions. The centroid-centroid distances are 3.803 (16) and 3.804 (17) Å.

Azo compounds in colon-specific drug delivery

Azo compounds have the potential to act as drug carriers that facilitate the selective release of therapeutic agents to the colon, and also to effect the oral administration of those macromolecular drugs that require colon-specific drug delivery. With some further research-driven refinements, these materials may lead to more efficient treatments for local conditions, such as colonic cancer or inflammatory bowel disease. This article provides an overview of the azo-based systems developed to date, identifies the requirements for an ideal carrier, and highlights the directions for further developments in the field of azo group-facilitated colonic delivery.

Ursodeoxycholic acid versus sulfasalazine in colitis-related colon carcinogenesis in mice

PURPOSE

Inflammation influences carcinogenesis. In the current study, we investigated whether ursodeoxycholic acid (UDCA) can inhibit colitis-related mouse colon carcinogenesis and compared it with the effects of sulfasalazine.

EXPERIMENTAL DESIGN

Male CD-1 mice were given a single i.p. injection of azoxymethane followed by 1-week oral exposure of 1% dextran sodium sulfate in drinking water. They are then maintained on a basal diet mixed with UDCA (0.016%, 0.08%, or 0.4%) or sulfasalazine (0.05%) for 17 weeks. At week 20, the tumor-inhibitory effects of both chemicals were assessed by counting the incidence and multiplicity of colonic neoplasms. The immunohistochemical expression of the proliferating cell nuclear antigen labeling index in colonic epithelial malignancies was also assessed. Finally, at week 5, the mRNA expressions for cyclooxygenase-2, inducible nitric oxide synthase, peroxisome proliferator-activated receptor-gamma, and tumor necrosis factor-alpha were measured in nontumorous mucosa.

RESULTS

Feeding the mice with UDCA at all doses significantly inhibited the multiplicity of colonic adenocarcinoma. The treatment also significantly lowered the proliferating cell nuclear antigen labeling index in the colonic malignancies. UDCA feeding reduced the expression of inducible nitric oxide synthase and tumor necrosis factor-alpha mRNA in the colonic mucosa, while not significantly affecting the expression of cyclooxygenase-2 mRNA and peroxisome proliferator-activated receptor-gamma mRNA. Sulfasalazine caused a nonsignificant reduction in the incidence and multiplicity of colonic neoplasia and did not affect these mRNA expression.

CONCLUSIONS

Our findings suggest that UDCA rather than sulfasalazine could serve as an effective suppressing agent in colitis-related colon cancer development in mice.

Molecular cloning, characterisation and ligand-bound structure of an azoreductase from Pseudomonas aeruginosa

The gene PA0785 from Pseudomonas aeruginosa strain PAO1, which is annotated as a probable acyl carrier protein phosphodiesterase (acpD), has been cloned and heterologously overexpressed in Escherichia coli. The purified recombinant enzyme exhibits activity corresponding to that of azoreductase but not acpD. Each recombinant protein molecule has an estimated molecular mass of 23,050 Da and one non-covalently bound FMN as co-factor. This enzyme, now identified as azoreductase 1 from Pseudomonas aeruginosa (paAzoR1), is a flavodoxin-like protein with an apparent molecular mass of 110 kDa as determined by gel-filtration chromatography, indicating that the protein is likely to be tetrameric in solution. The three-dimensional structure of paAzoR1, in complex with the substrate methyl red, was solved at a resolution of 2.18 A by X-ray crystallography. The protein exists as a dimer of dimers in the crystal lattice, with two spatially separated active sites per dimer, and the active site of paAzoR1 was shown to be a well-conserved hydrophobic pocket formed between two monomers. The paAzoR1 enzyme is able to reduce different classes of azo dyes and activate several azo pro-drugs used in the treatment of inflammatory bowel disease (IBD). During azo reduction, FMN serves as a redox centre in the electron-transferring system by mediating the electron transfer from NAD(P)H to the azo substrate. The spectral properties of paAzoR1 demonstrate the hydrophobic interaction between FMN and the active site in the protein. The structure of the ligand-bound protein also highlights the pi-stacking interactions between FMN and the azo substrate.

Beclomethasone dipropionate versus mesalazine in distal ulcerative colitis: a multicenter, randomized, double-blind study

BACKGROUND

Topical beclomethasone diproprionate has shown efficacy in ulcerative colitis.

AIM

To assess, in a multicenter, randomized, double-blind study, the tolerability and safety of topical beclomethasone diproprionate (3mg) enema and foam versus mesalazine (2g) enema and foam in mild-moderate distal ulcerative colitis.

PATIENTS

In 15 referral gastrointestinal units, 99 patients with distal ulcerative colitis were enrolled. This number was lower than planned according to the statistical analysis, due to a low recruitment rate.

METHODS

Patients were randomly assigned to random preparations (beclomethasone diproprionate enema, beclomethasone diproprionate foam, mesalazine enema, mesalazine foam) once nightly for 8 weeks, with clinical and endoscopical assessment (Disease Activity Index score) at baseline (T0), 4 (T4) and 8 weeks (T8). Results were expressed as median and range (95% confidence interval). The efficacy was assessed by comparing the Disease Activity Index value at T4 and T8 by using the Student's t-test or the Wilcoxon-Mann-Whitney test.

RESULTS

Efficacy was comparable in the beclomethasone diproprionate or mesalazine groups at both T4 and T8 (response at T4: beclomethasone diproprionate 78% [95% confidence interval 0.6-0.8] versus mesalazine 79% [95% confidence interval 0.6-0.8]; T8: beclomethasone diproprionate 84% [95% confidence interval 0.7-0.9] versus mesalazine 90% [95% confidence interval 0.7-1.0]; p=n.s.; remission at T4: beclomethasone diproprionate 24% [95% confidence interval 0.1-0.3] versus mesalazine 28% [95% confidence interval 0.1-0.3]; remission at T8: beclomethasone diproprionate 36% [95% confidence interval 0.2-0.5] versus mesalazine 52% [95% confidence interval 0.3-0.6]; p=n.s.). The Disease Activity Index lowered at T4 and T8 versus T0 in the four groups (T4 versus T0: beclomethasone diproprionate foam Disease Activity Index 2 versus 6 p<0.0001; beclomethasone diproprionate enema 4 versus 6, mesalazine enema 3 versus 6, mesalazine foam 3.5 versus 7, p<0.001 for all three groups; T8 versus T0: p<0.01). The Disease Activity Index lowered at T8 versus T4 in the beclomethasone diproprionate enema and foam (Disease Activity Index: 2 versus 4 and 1 versus 4, respectively; p<0.05) and in the mesalazine enema (Disease Activity Index: 1.5, range 0-4 versus 3, range 0-12; p<0.01), but not in the mesalazine foam group (Disease Activity Index: 1, range 0-9 versus 3.5, range 0-8; p=n.s.). The safety profile was favourable for all groups.

CONCLUSIONS

Beclomethasone diproprionate and mesalazine enema and foam show a comparable tolerability and efficacy in mild active distal ulcerative colitis.