An advanced microencapsulated system: a platform for optimized oral delivery of antidiabetic drug-bile acid formulations.

INTRODUCTION: In previous studies, we have shown that a gliclazide-cholic acid derivative (G-CA) mixture resulted in an enhanced ileal permeation of G (ex vivo). When administered orally to diabetic rats, it brought about a significant hypoglycaemic effect. In this study, we aim to create a novel microencapsulated-formulation of G-CA with uniform and coherent structure that can be further tested in our rat model of type 1 diabetes (T1D). We also aim to examine the effect of CA addition to G microcapsules in the morphology, structure and excipients' compatibility of the newly designed microcapsules. METHOD: Microencapsulation was carried out using our Buchi-based microencapsulating system developed in our laboratory. Using sodium alginate (SA) polymer, both formulations were prepared: G-SA (control) and G-CA-SA (test) at a constant ratio (1:3:30), respectively. Complete characterizations of microcapsules were carried out. RESULTS: The new G-CA-SA formulation is further optimized by the addition of CA exhibiting pseudoplastic-thixotropic rheological characteristics. Bead size remains similar after CA addition, the new microcapsules show no chemical interactions between the excipients and this was supported further by the spectral studies suggesting bead stability. CONCLUSION: The new microencapsulated-formulation has good and uniform structural properties and may be suitable for oral delivery of antidiabetic-bile acid formulations.

Stability and Release Kinetics of an Advanced Gliclazide-Cholic Acid Formulation: The Use of Artificial-Cell Microencapsulation in Slow Release Targeted Oral Delivery of Antidiabetics.

INTRODUCTION: In previous studies carried out in our laboratory, a bile acid (BA) formulation exerted a hypoglycaemic effect in a rat model of type-1 diabetes (T1D). When the antidiabetic drug gliclazide (G) was added to the bile acid, it augmented the hypoglycaemic effect. In a recent study, we designed a new formulation of gliclazide-cholic acid (G-CA), with good structural properties, excipient compatibility and exhibits pseudoplastic-thixotropic characteristics. The aim of this study is to test the slow release and pH-controlled properties of this new formulation. The aim is also to examine the effect of CA on G release kinetics at various pH values and different temperatures. METHOD: Microencapsulation was carried out using our Buchi-based microencapsulating system developed in our laboratory. Using sodium alginate (SA) polymer, both formulations were prepared: G-SA (control) and G-CA-SA (test) at a constant ratio (1:3:30), respectively. Microcapsules were examined for efficiency, size, release kinetics, stability and swelling studies at pH 1.5, pH 3, pH 7.4 and pH 7.8 and temperatures of 20 and 30 °C. RESULTS: The new formulation is further optimised by the addition of CA. CA reduced microcapsule swelling of the microcapsules at pH 7.8 and pH 3 at 30 °C and pH 3 at 20 °C, and, even though microcapsule size remains similar after CA addition, percent G release was enhanced at high pH values (pH 7.4 and pH 7.8, p < 0.01). CONCLUSION: The new formulation exhibits colon-targeted delivery and the addition of CA prolonged G release suggesting its suitability for the sustained and targeted delivery of G and CA to the lower intestine.

The Influence of Intestinal Tract and Probiotics on the Fate of Orally Administered Drugs.

Although the liver has long been considered as a main organ responsible for drug metabolism, the role of the gut metabolizing enzymes and the gut microflora is becoming more profoundly evident in drug metabolism, absorption and overall efficacy. This review will explore various mechanisms by which the gut-microflora influences drug pharmacokinetics including biotransformation, bioactivation, and biodegradation as well as up- or down-regulation of the epithelial transporters. The gut-luminal fluids, intestinal mucosa and gut microflora contain high concentrations of various enzymes which are responsible for the oxidation, hydrolysis and conjugation of drugs. Such metabolic reactions may lead to either drug over- or under-dosing, which impacts the drugs efficacy and safety. The processes, by which the intestinal enzymes and gut-protein transporters influence drug pharmacokinetic parameters, will be detailed. Since the intestinal microflora plays an important role in physiological, nutritional, metabolic, and immunological processes in human body, there is currently some interest in the manipulation of its composition and activity by administering probiotics. This review will also examine the capacity of probiotics to interact with resident microbial community, affecting the respective enzymes or by providing their own specific enzymatic activities that may consequently change the bioavailability and pharmacological activity of concomitantly taken drugs.

The impact of farnesoid X receptor activation on intestinal permeability in inflammatory bowel disease.

The most important function of the intestinal mucosa is to form a barrier that separates luminal contents from the intestine. Defects in the intestinal epithelial barrier have been observed in several intestinal disorders such as inflammatory bowel disease (IBD). Recent studies have identified a number of factors that contribute to development of IBD including environmental triggers, genetic factors, immunoregulatory defects and microbial exposure. The current review focuses on the influence of the farnesoid X receptor (FXR) on the inhibition of intestinal inflammation in patients with IBD. The development and investigation of FXR agonists provide strong support for the regulatory role of FXR in mucosal innate immunity. Activation of FXR in the intestinal tract decreases the production of proinflammatory cytokines such as interleukin (IL) 1-beta, IL-2, IL-6, tumour necrosis factor-alpha and interferon-gamma, thus contributing to a reduction in inflammation and epithelial permeability. In addition, intestinal FXR activation induces the transcription of multiple genes involved in enteroprotection and the prevention of bacterial translocation in the intestinal tract. These data suggest that FXR agonists are potential candidates for exploration as a novel therapeutic strategy for IBD in humans.