Bioadhesive Polymers - Synthesis, Evaluation and Application in Controlled Release Tablets

Abstract

Synthesis of series of cross linked polymers of methacrylic acid (PMAs) and acrylic acid ( P U S ) is reported. Polymers of both the types have been investigated f o r physiochemical properties like solubility, density, swelling index and equilibrium swelling. A suitable method was devised for study of bioadhesion. Floating tablets were prepared and coated with some of the synthesized polymers. The tablets were then evaluated for physical properties (including bioadhesion) as well as for drug content and in vitro drug release. The results were compared with those obtained with Carbopol 934P. Some polymers showed better bioadhesion and drug release pattern as compared to Carbopol 934P. * For Correspondance 1. Present address : U.S. Vitamins, Deonar, Bombay -400 088 2. Present address : Ion Exchange (India) Ltd., Ambarnath. a79 Copyright 0 199 1 by Marcel Dekker, Inc. Drug Dev Ind Pharm Downloaded from informahealthcare.com by University of Otago on 12/27/14 For personal use only. Drug Dev Ind Pharm Downloaded from informahealthcare.com by University of Otago on 12/27/14 For personal use only.pH of Suspension : The pH of a 0 . 5 % suspension of polymer in deionised water and in 0.5% carbopol 934 P gel was read. The aqueous supensions gave pH in the range of 4.15 to 4.55. Addition of the polymer to carbopol further reduced pH of suspension to between 3.7 and 3 . 8 .Effect of DH on Eauilibrium Swellins of Polvmers : A 0.1% suspension of the polymer was prepared in deionised water, Drug Dev Ind Pharm Downloaded from informahealthcare.com by University of Otago on 12/27/14For personal use only.

Formulation and evaluation of glipizide floating-bioadhesive tablets

“…Chitnis et al (1991) synthesized a series of bioadhesive polymers that were cross-linked polymers of PMA and CP. Floating tablets of isosorbide mononitrate were prepared and then coated with these polymers.…”

“…However, as the stomach empties and the tablet is at the pylorus, the buoyancy of the dosage form may be impeded (Chueh, Zia, and Rhodes 1995). This serious limitation can be overcome by using bioadhesive polymers to enable it to adhere to the mucous lining of the stomach wall (Chitnis, Malshe, and Lalla 1991). Floating and bioadhesive drug delivery systems offer the advantages of increased contact time with stomach mucusa, more effective absorption and bioavailability of drugs with absorption windows near proximal intestine and stomach, and low dosing frequencies (Lehr CM et al 1992;Chueh et al1995 andRao et al 1997).…”

Amoxycillin Trihydrate Floating-Bioadhesive Drug Delivery System for Eradication of Helicobacter pylori: Preparation, In Vitro and Ex Vivo Evaluation

“…But, the main drawback of FDDS is that it is effective only when the fluid level in the stomach is sufficiently high, which aids in the buoyancy of the dosage form [13]. This limitation can be overcome by using bioadhesive polymers which enable it to adhere to the mucous lining of the stomach wall [14]. Floating-bioadhesive drug delivery systems offer the advantages of increased contact time with stomach mucosa resulting in more effective absorption, improving the bioavailability of drugs with absorption window high in the stomach and proximal intestine and reduced dosing frequencies [13].…”

Formulation and Optimization of Gastric Bioadhesive Tablets of Diltiazem Hydrochloride using Central Composite Design

“…Various approaches including floating systems, bioadhesive systems, swelling and expanding systems and high density systems have been successfully employed to improve the gastric residence time of a delivery system [4,5]. Though highly efficient for gastroretention, floating systems suffer from a major disadvantage that they are effective only when the fluid level in the stomach is sufficiently high.…”