Delivery of Exenatide and Insulin Using Mucoadhesive Intestinal Devices.

A major disadvantage associated with current diabetes therapy is dependence on injectables for long-term disease management. In addition to insulin, incretin hormone replacement therapies including exenatide have added a new class of drugs for Type-2 diabetes. Although efficacious, patient compliance with current diabetic therapy is poor due to requirement of injections, inability to cross the intestinal epithelium and instability in the gastrointestinal tract. Here, we report the efficacy of a mucoadhesive device in providing therapeutic concentrations of insulin and exenatide via oral administration. Devices were prepared with a blend of FDA-approved polymers, carbopol, pectin and sodium carboxymethylcellulose, and were tested for drug carrying capability, in vitro release, Caco-2 permeability, and in vivo efficacy for insulin and exenatide. Results suggested that mucoadhesive devices successfully provided controlled release of FITC-insulin, released significant amounts of drug, while providing noteworthy enhancement of drug transport across Caco-2 monolayers without compromising monolayer integrity. In-vivo administration of the devices provided significant enhancement of drug absorption with 13- and 80-fold enhancement of relative bioavailability for insulin and exenatide compared to intestinal injections with significant increase in half-lives, thus resulting in prolonged blood glucose reduction. This study validates the efficacy of mucoadhesive devices in promoting oral peptide delivery to improve patient compliance and dose adherence.

Mucoadhesive intestinal devices for oral delivery of salmon calcitonin.

One of the major challenges faced by therapeutic polypeptides remains their invasive route of delivery. Oral administration offers a potential alternative to injections; however, this route cannot be currently used for peptides due to their limited stability in the stomach and poor permeation across the intestine. Here, we report mucoadhesive devices for oral delivery that are inspired by the design of transdermal patches and demonstrate their capabilities in vivo for salmon calcitonin (sCT). The mucoadhesive devices were prepared by compressing a polymeric matrix containing carbopol, pectin and sodium carboxymethylcellulose (1:1:2), and were coated on all sides but one with an impermeable and flexible ethyl cellulose (EC) backing layer. Devices were tested for in vitro dissolution, mucoadhesion to intestinal mucosa, enhancement of drug absorption in vitro (Caco-2 monolayer transport) and in vivo in rats. Devices showed steady drug release with ≈75% cumulative drug released in 5h. Devices also demonstrated strong mucoadhesion to porcine small intestine to withstand forces up to 100 times their own weight. sCT-loaded mucoadhesive devices exhibited delivery of sCT across Caco-2 monolayers and across the intestinal epithelium in vivo in rats. A ≈52-fold (pharmacokinetic) and ≈44-fold (pharmacological) enhancement of oral bioavailability was observed with mucoadhesive devices when compared to direct intestinal injections. Oral delivery of devices in enteric coated capsules resulted in significant bioavailability enhancement.

Permeation of insulin, calcitonin and exenatide across Caco-2 monolayers: measurement using a rapid, 3-day system.

OBJECTIVES: Caco-2 monolayers are one of the most widely used in vitro models for prediction of intestinal permeability of therapeutic molecules. However, the conventional Caco-2 monolayer model has several drawbacks including labor-intensive culture process, unphysiological growth conditions, lack of reproducibility and limited throughput. Here, we report on the use of 3-day Caco-2 monolayers for assessing permeability of polypeptide drugs. METHODS: The 3-day monolayers were grown in a commercially available transwell set-up, which facilitates rapid development of the Caco-2 monolayers in an intestinal epithelial differentiation mimicking environment. This set-up included use of serum-free medium of defined composition with supplements such as butyric acid, hormones, growth factors, and other metabolites, reported to regulate the differentiation of intestinal epithelial cells in vivo. We measured permeability of 3 different therapeutic polypeptides; insulin, calcitonin, and exenatide across the monolayer. RESULTS: Preliminary validation of the monolayer was carried out by confirming dose-dependent permeation of FITC-insulin and sulforhodamine-B. Transport of insulin, calcitonin, and exenatide measured at different loading concentrations suggests that the permeability values obtained with 3-day cultures resemble more closely the values obtained with ex vivo models compared to permeability values obtained with conventional 21-day cultures. CONCLUSIONS: Short-term 3-day Caco-2 monolayers provide new opportunities for developing reproducible and high-throughput models for screening of therapeutic macromolecules for oral absorption.

Macrophages recognize size and shape of their targets.

Recognition by macrophages is a key process in generating immune response against invading pathogens. Previous studies have focused on recognition of pathogens through surface receptors present on the macrophage's surface. Here, using polymeric particles of different geometries that represent the size and shape range of a variety of bacteria, the importance of target geometry in recognition was investigated. The studies reported here reveal that attachment of particles of different geometries to macrophages exhibits a strong dependence on size and shape. For all sizes and shapes studied, particles possessing the longest dimension in the range of 2-3 microm exhibited highest attachment. This also happens to be the size range of most commonly found bacteria in nature. The surface features of macrophages, in particular the membrane ruffles, might play an important role in this geometry-based target recognition by macrophages. These findings have significant implications in understanding the pathogenicity of bacteria and in designing drug delivery carriers.