Decreased faecal exoglycosidase activities identify a subset of patients with active Crohn's disease

Novel Strategies to Prevent Total Parenteral Nutrition-Induced Gut and Liver Inflammation, and Adverse Metabolic Outcomes

Total parenteral nutrition (TPN) is a life-saving therapy administered to millions of patients. However, it is associated with significant adverse effects, namely liver injury, risk of infections, and metabolic derangements. In this review, the underlying causes of TPN-associated adverse effects, specifically gut atrophy, dysbiosis of the intestinal microbiome, leakage of the epithelial barrier with bacterial invasion, and inflammation are first described. The role of the bile acid receptors farnesoid X receptor and Takeda G protein-coupled receptor, of pleiotropic hormones, and growth factors is highlighted, and the mechanisms of insulin resistance, namely the lack of insulinotropic and insulinomimetic signaling of gut-originating incretins as well as the potentially toxicity of phytosterols and pro-inflammatory fatty acids mainly released from soybean oil-based lipid emulsions, are discussed. Finally, novel approaches in the design of next generation lipid delivery systems are proposed. Propositions include modifying the physicochemical properties of lipid emulsions, the use of lipid emulsions generated from sustainable oils with favorable ratios of anti-inflammatory n-3 to pro-inflammatory n-6 fatty acids, beneficial adjuncts to TPN, and concomitant pharmacotherapies to mitigate TPN-associated adverse effects.

Diarrhea caused by carbohydrate malabsorption

This article will focus on the role of the colon in the pathogenesis of diarrhea in carbohydrate malabsorption or physiologically incomplete absorption of carbohydrates, and on the most common manifestation of carbohydrate malabsorption, lactose malabsorption. In addition, incomplete fructose absorption, the role of carbohydrate malabsorption in other malabsorptive diseases, and congenital defects that lead to malabsorption will be covered. The article concludes with a section on diagnostic tools to evaluate carbohydrate malabsorption.

New oral delivery systems for treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD) is often localized to specific sites in the gastrointestinal tract (GIT). As a result, this disease can be treated with oral site-specific (targeted) drug delivery systems. Targeted delivery systems for treatment of IBD are designed to increase local tissue concentrations of antiinflammatory drugs from lower doses compared with systemic administration. This review addresses the impact disease has or may have on oral targeted delivery for treatment of IBD as well as a number of delivery approaches currently used in marketed products or under investigation. Delivery systems reviewed rely on temporal control, changes in pH along the GIT, the action of local enzymes to trigger drug release, and changes in intraluminal pressure. Dissolution of enteric polymer coatings due to a change in local pH and reduction of azo-bonds to release an active agent are both used in commercially marketed products. Newer approaches showing promise in treating IBD are based on polysaccharides. These materials are most effective when used as compression coatings around core tablets, which contain the active agent. More complex polymeric prodrugs systems are also under investigation. If the dose of the drug is sufficiently low, this approach may also prove useful in improving treatment of IBD.

Effects of probiotic administration upon the composition and enzymatic activity of human fecal microbiota in patients with irritable bowel syndrome or functional diarrhea

In a clinical trial, 10 patients suffering from irritable bowel syndrome or functional diarrhea were administered the probiotic preparation VSL-3. Preliminary results indicated that administration of VSL-3 improved the clinical picture and changed the composition and biochemistry of fecal microbiota. Titer variations of intestinal bacterial groups were evaluated by culture and PCR techniques. A significant increase in lactobacilli, bifidobacteria and Streptococcus thermophilus was observed as a consequence of probiotic treatment, while enterococci, coliforms, Bacteroides and Clostridium perfringens did not change significantly. The strains Bifidobacterium infantis Y1 and Bifidobacterium breve Y8, included in VSL-3, were specifically detected in feces of patients treated with the probiotic by using strain-specific PCR primers. In addition, fecal beta-galactosidase increased and urease activities decreased as a result of changes in the intestinal microbiota induced by VSL-3 administration.

Review article: issues in oral administration of locally acting glucocorticosteroids for treatment of inflammatory bowel disease

Inflammatory bowel diseases are treated in some cases by local administration of anti-inflammatory drugs. Local delivery of drugs in the colon following oral administration may lead to improved efficacy/side-effect profiles and may improve patient compliance. This review covers a number of issues important in the design of oral delivery systems of glucocorticosteroids for local therapy of colonic inflammation. The choice of specific glucocorticosteroids is based on the drug's physicochemical and pharmacological properties. The conditions under which an orally administered glucocorticosteroid (or other drug) must be delivered to treat ulcerative colitis are also discussed. These conditions include variations in local pH, transit throughout the gastrointestinal tract, the potential role of gut microflora, and drug dissolution in both the healthy and diseased large intestine. The effective delivery of topically-active glucocorticosteroids in ulcerative colitis and Crohn's colitis patients is complex, but if successful could improve their usefulness.

Bacterial enzymes used for colon-specific drug delivery are decreased in active Crohn's disease

Enzymes produced by colonic microflora have been proposed for triggering local delivery of antiinflammatory azo-bond drugs and prodrugs to the colon. This approach could be advantageous in steroid treatment of inflammatory bowel diseases, thus sparing steroids' side effects. We recently demonstrated that the metabolic activity of digestive flora, assessed on the activity of fecal glycosidases, was decreased in patients with active Crohn's disease. In the present study, the azoreductase activity in feces of 14 patients with active Crohn's disease was decreased (11.39 +/- 7.93 mU/g F) as compared with 12 healthy subjects (51.13 +/- 21.39 mU/g F). beta-D-Glucosidase and beta-D-glucuronidase activities in fecal homogenates incubated under anaerobic conditions were also decreased in patients. These data bring into question the therapeutic usefulness for those patients of azo-bond drugs and glycoside prodrugs. They could explain the therapeutic failure of some of those drugs in active ileocolic and colic Crohn's disease.

Budesonide-beta-D-glucuronide: a potential prodrug for treatment of ulcerative colitis

Budesonide-beta-D-glucuronide is a potentially useful orally administered prodrug for the treatment of colonic inflammatory bowel disease. Budesonide is a topically active glucocorticosteroid that exhibits low oral bioavailability (15%) in humans and laboratory animals. Oral delivery of budesonide to the inflamed tissues of the large intestine as its glucuronide prodrug should lead to locally high concentrations of active drug. Following liberation and absorption of the active drug, a large portion should be inactivated due to hepatic metabolism. Budesonide-beta-D-glucuronide was chemically stable in solutions at pHs of 1.5, 4.5, 6.5, and 7.4 at 37 degrees C. The enzymatic lability of the prodrug was assessed in luminal contents and mucosa obtained from conventional, germ-free, and colitic rats under in vitro conditions. There was a substantial change in glycosidase activity between the small intestine (proximal and distal portions) and the cecum in both conventional and colitic rat luminal contents. Luminal hydrolytic activity was low along the entire rat gastrointestinal tract of germ-free rats. Mucosal glycosidase activity was relatively low along the entire gastrointestinal tract of all three types of rats. The hydrolysis of prodrugs budesonide-beta-D-glucuronide and dexamethasone-beta-D-glucuronide in human fecal samples from patients with ulcerative colitis and normal volunteers was also measured. There were no statistically significant differences between the normal and colitic fecal samples for hydrolysis of the either prodrug or between the relative rates of hydrolysis of the two prodrugs. Hydrolysis rates of the prodrugs were about two orders of magnitude less in human fecal samples compared with those in cecal and colonic contents from the rat.

In vitro evaluation of dexamethasone-beta-D-glucuronide for colon-specific drug delivery

Dexamethasone-beta-D-glucuronide is a potential prodrug for colonic delivery of the antiinflammatory corticosteroid dexamethasone. Previous studies [T. R. Tozer et al., Pharm. Res. 8:445-454 (1991)] indicated that a glucoside prodrug of dexamethasone was susceptible to hydrolysis in the upper gastrointestinal tract. Resistance of dexamethasone-beta-D-glucuronide to hydrolysis in the upper gastrointestinal tract was therefore assessed. Conventional, germfree, and colitic rats were used to examine enzyme levels along the gastrointestinal tract to compare the stability of two model substrates (p-nitrophenyl-beta-D-glucoside and -beta-D-glucuronide) and to evaluate the prodrug dexamethasone-beta-D-glucuronide. Hydrolytic activity was examined in the luminal contents, mucosa, and underlying muscle/connective tissues in all three types of rats. Enzymatic activity (beta-D-glucosidase and beta-D-glucuronidase) was greatest in the lumen of cecum and colon of conventional rats. In contrast, germ-free rats exhibited relatively high levels of beta-D-glucosidase activity (about 80% of total activity in the conventional rats) in the proximal small intestine (PSI) and the distal small intestine (DSI). Rats with induced colitis (acetic acid) showed reduced levels of luminal beta-D-glucuronidase activity in the large intestine; however, beta-D-glucosidase activity was relatively unchanged relative to that of the conventional rat. Mucosal beta-D-glucuronidase activity was significantly lower in the colitic rats compared with that in the conventional animals. Despite reduced luminal levels of beta-D-glucuronidase activity in the colitic rats, there was still a sharp gradient of activity between the small and the large intestines. Permeability of the glucoside and glucuronide prodrugs of dexamethasone through a monolayer of Caco-2 cells was relatively low compared to that of dexamethasone. The results indicate that dexamethasone-beta-D-glucuronide should be relatively stable and poorly absorbed in the upper gastrointestinal tract. Once the compound reaches the large intestine, it should be hydrolyzed to dexamethasone and glucuronic acid. Specificity of colonic delivery in humans should be even greater due to lower levels of beta-D-glucuronidase activity in the small intestine compared with that in the laboratory rat.