Utility of an oxidation reaction for the spectrophotometric determination of acarbose in controlled release tablets at various simulated gastrointestinal media.

A sensitive kinetic method for spectrophotometric determination of acarbose is developed and validated for the determination of the drug in bulk and pharmaceutical formulations. The drug was estimated in simulated gastrointestinal media i.e., 0.1 M HCl (pH 1.2) and phosphate buffer (pH 6.8). The method involves the oxidation of acarbose by treating it with a strong oxidizing agent (potassium permanganate (1 x 10(-2) M)) in alkaline media. The reaction kinetics was determined for 20 min at room temperature. The reaction followed first order kinetics and the absorbance of the corresponding manganate ions produced was determined at 610 nm. The absorbance-concentration plot was found to be rectilinear over the concentration range of 2-20 microg/mL. The proposed method was used for estimation of the drug in a novel controlled release dosage form. Thus, the method developed was simple, reproducible and can be successfully applied for the determination of the drug in simulated gastrointestinal fluid.

Newer insights into the drug delivery approaches of α-glucosidase inhibitors.

INTRODUCTION: α-Glucosidase inhibitors (AGIs) are an important category of oral antidiabetic agents being extensively exploited for the effective management of type 2 diabetes and associated disorders. These drugs significantly reduce the postprandial rise in glycemic and plasma insulin levels both in nondiabetics and in type 2 diabetic patients. Currently only three drugs belonging to this category, viz, acarbose, miglitol and voglibose are in the market. The major limitations associated with the administration of AGIs are the stringent repetitive dosing schedule at specified time intervals, along with a high incidence of gastrointestinal disturbances that mainly include flatulence, abdominal distension, borborygmus and diarrhea. All these factors tend to decrease patient compliance. AREAS COVERED: This review focuses on the various formulation approaches being targeted for the effective delivery of AGIs, viz, unit matrix systems, bioadhesive pellets, hydrogels and lipid-based granules. EXPERT OPINION: It is concluded that development of a successful controlled-release delivery system for these drugs will obviate the need of repeated administration, which in turn will improve patient compliance.

A novel synergistic galactomannan-based unit dosage form for sustained release of acarbose.

In the current study, the potential of a novel combination of a galactomannan with acarbose (100 mg) was evaluated for attaining a desired hypoglycaemic effect over a prolonged period of time. Three major antidiabetic galactomannans viz., fenugreek gum, Boswellia gum, and locust bean gum were selected in order to achieve a synergistic effect in the treatment along with retardation in drug release. In vitro studies indicated that batches containing various proportions of fenugreek gum (AF40-60) were able to control drug release for a longer duration of approximately 10-12 h. In contrast, the matrices prepared using Boswellia and locust bean gum were able to sustain the release for relatively shorter durations. Drug release mainly followed first-order release kinetics owing to the highly soluble nature of the drug. In vivo study depicted a significant reduction (p < 0.001) in the postprandial blood glucose and triglyceride levels in the diabetic rats on treatment with formulation AF40. Thus, the developed system provides a better control of the postprandial glycaemic levels and it also obviates the need of conventional multiple dosing of acarbose. Furthermore, it also reduces the occurrence of side effects like diarrhea and loss of appetite.

Tailoring of drug delivery of 5-fluorouracil to the colon via a mixed film coated unit system.

The study was carried out to establish the effectiveness of a mixed film composed of ethylcellulose/Eudragit S100 for colonic delivery of 5-flourouracil (5-FU). Tablets cores containing 5-FU were prepared by direct compression method by coating at different levels (2-9%, m/m) with a non-aqueous solution containing ethylcellulose/Eudragit S100. Coated tablets were studied for the in vitro release of 5-FU and the samples were analyzed spectrophotometrically at 266 nm. Drug release from coated systems depended on the thickness of the mixed film and the composition of the core. Channel formation was initiated in the coat by dissolution of the Eudragit S100 fraction at higher pH in the colonic region. The release was found to be higher in tablets containing Avicel as filler owing to its wicking action compared to that from lactose containing cores. Furthermore, batches containing superdisintegrant (1%, m/m Cross-PVP) along with Avicel in the core released approximately 81.1% drug during the colonic transit time. Kinetic studies indicated that all the formulations followed first-order release kinetics. The developed delivery system will expectedly deliver the drug to the colon.

Oral colon-specific drug delivery of protein and peptide drugs.

With the advent of new technologies and radical growth in the field of biotechnology, dozens of protein and peptide drugs have been marketed. However, there are several challenges for successful delivery of such molecules. A number of routes have been used for the delivery of these fragile molecules by exploring various novel delivery technologies, including microspheres, liposomes, gel spheres, nano-spheres, niosomes, microemulsions, use of permeation enhancers, use of protease inhibitors, etc. But the route that has attracted the attention of worldwide drug delivery scientists is the oral route due to its various advantages. Even though the proteolytic activity is higher in a few segments of the gastrointestinal tract (GIT), this route has certain segments that have lower proteolytic activity, for example, the colon. The colon has captured attention as a site for the delivery of these molecules because of its greater responsiveness to absorption enhancers, protease inhibitors, and novel bioadhesive and biodegradable polymers. Although the success rate of these approaches, when used alone is pretty low, when used in combinations, these agents have demonstrated wonders in increasing the drug bioavailability. This review focuses on the challenges, pharmaceutical concepts, and approaches involved in the delivery of these fragile molecules, specifically to the colon. This review also includes studies conducted on colonic targeting of such drugs. Further studies may lead to improvements in therapy using protein/peptide drugs and refinements in the technology of colon-specific drug delivery.