Brush-border-enzyme-mediated intestine-specific drug delivery. Amino acid prodrugs of 5-aminosalicylic acid

Global trends and hotspots of ulcerative colitis based on bibliometric and visual analysis from 1993 to 2022

Ulcerative colitis (UC) has seen a significant increase over the past 3 decades. However, our understanding of its etiology, pathogenesis, and pharmacological treatment remains limited. This comprehensive review aims to address these gaps by analyzing trends, evaluating previous research, and providing insights for future investigations. We conducted a bibliometric analysis of UC-related papers indexed in the Web of Science from 1993 to 2022. The author, organization, country, and keyword networks in the field of UC were visualized. A total of 36,483 papers were included, showing a continuous upward trend. Most research on UC was conducted in universities, with hospitals leading in high-quality studies. The United States emerged as the primary contributor, followed by China and the United Kingdom. The overall quality of UC-related publications improved, indicating sustained interest in the field. The keywords related to UC was classified into 9 clusters. Keywords detection revealed that UC research focused mainly on the discovery of its etiology and exploration of treatment methods, with research directions evolving from initial treatment of UC and related diseases to clinical trials of UC and subsequently incorporating genomics and bioinformatics techniques to study UC and explore new therapeutic methods and drugs, including recent advances in gut microbiota. Our study identified gaps in understanding the etiology, pathogenesis, and treatment of UC. Future research in UC should focus on genomics, personalized treatment, microbial therapy and leveraging machine learning and artificial intelligence. These areas hold the potential for improving UC diagnosis, treatment, and management.

Design and evaluation of colon specific drug delivery system containing flurbiprofen microsponges

The purpose of this study was to design novel colon specific drug delivery system containing flurbiprofen (FLB) microsponges. Microsponges containing FLB and Eudragit RS 100 were prepared by quasi-emulsion solvent diffusion method. Additionally, FLB was entrapped into a commercial Microsponge 5640 system using entrapment method. Afterwards, the effects of drug:polymer ratio, inner phase solvent amount, stirring time and speed and stirrer type on the physical characteristics of microsponges were investigated. The thermal behaviour, surface morphology, particle size and pore structure of microsponges were examined. The colon specific formulations were prepared by compression coating and also pore plugging of microsponges with pectin:hydroxypropylmethyl cellulose (HPMC) mixture followed by tabletting. In vitro dissolution studies were done on all formulations and the results were kinetically and statistically evaluated. The microsponges were spherical in shape, between 30.7 and 94.5microm in diameter and showed high porosity values (61-72%). The pore shapes of microsponges prepared by quasi-emulsion solvent diffusion method and entrapment method were found as spherical and cylindrical holes, respectively. Mechanically strong tablets prepared for colon specific drug delivery were obtained owing to the plastic deformation of sponge-like structure of microsponges. In vitro studies exhibited that compression coated colon specific tablet formulations started to release the drug at the 8th hour corresponding to the proximal colon arrival time due to the addition of enzyme, following a modified release pattern while the drug release from the colon specific formulations prepared by pore plugging the microsponges showed an increase at the 8th hour which was the time point that the enzyme addition made. This study presents a new approach based on microsponges for colon specific drug delivery.

Synthesis of a novel prodrug of 3-(4'-geranyloxy-3'-methoxyphenyl)-2-trans-propenoic acid for colon delivery

A novel high-yielding and environment-friendly synthesis of the anticancer compound 3-(4'-geranyloxy-3'-methoxyphenyl)-2-trans-propenoic acid is described. This compound was conjugated to H2N-Ala-Pro dipeptide to give a prodrug to be activated by intestinal ACE and to be used in the treatment of different forms of colon cancer. Data on the chemical and enzymatic stability of this novel prodrug are reported.

Technology to obtain sustained release characteristics of drugs after delivered to the colon

To determine the necessary technology by which sustained drug release is obtained after drug is delivered to the colon, two kinds of microcapsules were prepared and were filled in a pressure-controlled colon delivery capsule (PCDC). As a model drug 5-aminosalicylic acid (5-ASA) was used, because the target site of 5-ASA is the entire large intestine. 5-ASA was microencapsulated using a water-insoluble polymer, ethylcellulose (EC) or with pH-sensitive polymers, Eudragit L-100 or S-100 and encased in PCDC. The particle size of these microcapsules was around 800 microns and the loading efficiencies of 5-ASA were approximately 90%. In vitro dissolution tests were performed with the prepared microcapsules. The release rate of 5-ASA from the microcapsules was significantly prolonged as compared to 5-ASA powder, although there were no significant differences in the release rates between these microcapsules. By incorporating the 5-ASA microcapsules into PCDC, sustained release PCDCs for colon delivery were prepared and in vivo evaluation was performed using beagle dogs. As a fast release colon delivery system, PCDCs were prepared with 5-ASA powder suspended in suppository base. After oral administration of the test preparations to beagle dogs, plasma 5-ASA concentrations were measured and sustained release characteristics of 5-ASA from the test preparations were evaluated from the plasma 5-ASA concentration-time profiles. The first appearance time of 5-ASA into the systemic circulation after oral administration were 3 h for all the colon delivery preparations and it was thought that these test preparations were delivered to the colon. Both EC microcapsules and Eudragit S-100/RS-100 microcapsules in PCDC showed longer the mean residence time MRT, 8.2 +/- 0.6 h and 8.7 +/- 0.9 h, than Eudragit L-100/RS-100 microcapsules in PCDC where the MRT was 6.6 +/- 0.2 h. Since PCDCs containing 5-ASA powder exhibited a MRT of 7.0 +/- 1.0 h, these two types of preparations have suggested sustained release characteristics.

Synthesis and properties of dextran-5-aminosalicylic acid ester as a potential colon-specific prodrug of 5-aminosalicylic acid

Dextran-5-aminosalicylic acid ester (dextran-5-ASA) was synthesized as a colon-specific prodrug of 5-aminosalicylic acid (5-ASA) which is active against inflammatory bowel diseases. Chemical stability of dextran-5-ASA in the bath of pH 1.2 or 6.8 was investigated at 37 degrees C for 6 hrs, and 5-ASA was not released on such conditions. Depolymerization (%) of dextran-5-ASA by dextranase with the degree of substitution (DS) of 18, 23, or 30 was 92, 62 or 45 in 8 hrs respectively, but was not affected by the MW of dextran (9,000, 40,600, 80,200 or 580,000). Distribution of 5-ASA in dextran, determined by gel filtration chromatography, appeared to be relatively uniform. Incubation of dextran-5-ASA (DS 18) in cecal contents of rats released 20% (28 g) and 35% (49 g) of 5-ASA in 8 hrs and 24 hrs, respectively, but no 5-ASA was liberated from small intestinal contents.

Application of a colon delivery capsule to 5-aminosalicylic acid and evaluation of the pharmacokinetic profile after oral administration to beagle dogs

Pressure-controlled colon delivery capsule (PCC) containing 5-aminosalicylic acid (5-ASA) for the treatment of inflammatory bowel disease (IBD) was prepared and evaluated by an in vivo experiment using beagle dogs. As a reference drug, sulfasalazine (SASP), prodrug of 5-ASA, was used as a plain gelatin capsule preparation. After the oral administration of SASP at the does of 25.0 mg/kg, the mean time when the plasma 5-ASA concentration reaches to its maximum (Tmax) was 9.0 hr. In the case of 5-ASA administered in PCC, at the doses of 12.5 and 25.0 mg/kg, Tmaxs were 5.3 and 5.3 hr, respectively. Although the time for the first appearance of 5-ASA into the systemic circulation was almost the same value between SASP capsule and PCC containing 5-ASA, longer Tmax was observed from SASP capsule than from PCC. These results suggest that this 5-ASA preparation would be an useful dosage form for the therapy of IBD from the point of avoiding the side effect of sulfapyridine, one of the metabolites of SASP.

Effect of food intake on the delivery of fluorescein as a model drug in colon delivery capsule after oral administration to beagle dogs

The effect of food on the release time of a model drug, fluorescein (FL), has been studied after oral administration to beagle dogs in colon delivery capsule in comparison to conventional gelatin capsule and enteric capsules. The dose of FL was 30 mg for each animal. After oral administration of each test preparation in fasted or postprandial condition (100 grams of commercial solid food was given at 30 min before drug administration), blood samples were collected and plasma FL concentrations were measured spectrofluorometrically. Pharmacokinetic analysis was performed with plasma FL concentration vs. time data and the following parameters were determined; Tmax (the time when plasma FL concentration reaches to its maximum concentration), Cmax (peak plasma FL concentration), Tlag (the time when FL appeared at first into the systemic circulation), AUC (area under the plasma FL concentration vs. Time curve) and MRT (mean residence time). For gelatin capsule, mean Tmax appeared at 0.83 +/- 0.33 (S.E.) h after administration and MRT was 2.67 +/- 0.21 h in fasted condition. By feeding, Tmax and MRT increased to 1.50 +/- 0.76 h and 3.09 +/- 0.49 h. For two enteric HPMCP and Eudragit S capsules, MRT were 2.90 +/- 0.48 h and 5.24 +/- 0.32 h in fasted condition, and 11.30 +/- 1.10 h and 12.83 +/- 0.34 h in postprandial condition, respectively. Tlag also increased by postprandial administration. As colon delivery capsule, time-controlled release capsule (TCC) and two types of intestinal inner pressure-controlled release capsules (PCC) (#1 is a separate type and #2 is a seamless one) were tested. MRT of TCC was 4.76 +/- 0.29 h and 6.43 +/- 0.66 h in fasted and postprandial conditions, respectively. This capsule did not receive the effect of food intake. For #1 PCC, MRTs were 5.32 +/- 0.22 h and 12.28 +/- 0.26 h in fasted and postprandial conditions, respectively. For #2 PCC, MRTs were 5.51 +/- 0.26 h and 13.36 +/- 0.84 h in fasted and postprandial conditions, respectively. In addition, the effect of two times feedings was studied with two PCCs and longer MRTs, 28.44 +/- 1.39 h and 26.32 +/- 1.64 h, were obtained. The release time of FL from PCCs increased by postprandial administration. As compared to the results on two enteric capsules, these PCCs are thought to disintegrate in the colon. However, TCC is thought to disintegrate in the stomach after postprandial administration.

Appraisal of a glycopeptide cloaking strategy for a therapeutic oligopeptide: glycopeptide analogs of the renin inhibitor ditekiren

Among the limitations to the practical therapeutic oligopeptide are low oral availability, indifferent aqueous solubility, and an astonishing efficient sequestration and biliary elimination by a multi-capacity liver transporter. Given the purposed use of N- and O- linked saccharides as functional appendages of eukaryotic peptides and proteins, a strategy of glycopeptide mimicry was examined for the oligopeptide renin inhibitor, ditekiren. The anticipation was that the saccharide would impart significant aqueous solubility, and might impact beneficially on the remaining two limitations. Execution of this approach was achieved by the removal of the (dimethylethoxy)carbonyl amino terminus of ditekiren, and its substitution by Boc-L-asparagine N-linked mono- and disaccharides. Potent hypotensive activity, as measured by a human renin-infused rat assay, is observed for virtually all of these structures (N-linked beta-pyranose D-N-acetyglucosaminyl, D-glucosaminyl, D-N-acetylgalactosaminyl, D-mannosyl, D-galactosyl, D-maltosyl, D-cellobiosyl, D-chitobiosyl, but not L-fucosyl). The basis for this dramatic improvement (relative to ditekiren in the same assay) is the diversion of the peptide clearance from rapid liver biliary clearance to slower urinary clearance (Fisher, J. F.; Harrison, A. W.; Wilkinson, K. F.; Rush, B. R.; Ruwart, M. J. J. Med. Chem. 1991, 34, 3140). Guided by the human renin-infused rat hypertension assay, an evaluation of the linker-saccharide pairing was made. Loss of hypotensive activity is observed upon substitution of the Boc-L-asn by Boc-D-asn, and by removal of the Boc amino terminus of the glycopeptide. Potent hypotensive activity is preserved by replacement of the Boc-L-asn linker by succinate, malate, tartrate, and adipate linkers. With the longer adipate spacer, attachment of the saccharide to the P-3 phenylalanine--with omission of the P-4 proline--retains activity. These data suggest value to the glycopeptide guise for preserving the in vivo activity, and for the beneficial manipulation of pharmacodynamics, of this renin inhibitory oligopeptide. This strategy may have general applicability.