The suitability of tris(hydroxylmethyl) aminomethane (THAM) as a buffering system for hydroxypropyl methylcellulose (HPMC) hydrophilic matrices containing a weak acid drug

Microenvironmental pH Control and Mixed Polymer Approaches to Optimise Drug Delivery with Hydrophilic Matrix Tablets

“…The study showed how drug release, in both pH 1.2 and 7.5 media, was accelerated by both buffers, but tromethamine-buffered matrices provided extended, diffusion-based release kinetics, without loss of matrix integrity, at high matrix buffer content [16]. Drug release kinetics appeared to be independent of media pH.…”

“…Using a 100 μm diameter electrode, it was possible to monitor dynamic changes in the gel layer of a hydrophilic matrix tablet containing tromethamine or sodium citrate as a pH modifier [15,16]. In another study, a special microelectrode (diameter 10 μm) was utilised to follow the pH gradient in an extendedrelease hydrophilic matrix tablet containing the active ingredient vincamine hydrochloride and succinic acid as pH modifier.…”

“…The comparison of tris(hydroxymethyl) aminomethane (tromethamine, THAM, TRIS, trometamol) with sodium citrate as internal buffering agents for HPMC (4,000 cps) 2208 and 2910 matrices containing felbinac, a weak acid drug which exhibits pH-dependent solubility was reported [16]. The study showed how drug release, in both pH 1.2 and 7.5 media, was accelerated by both buffers, but tromethamine-buffered matrices provided extended, diffusion-based release kinetics, without loss of matrix integrity, at high matrix buffer content [16].…”

Polysaccharide Based Formulations for Mucosal Drug Delivery: A Review

“…Water-soluble hydrophilic polymers hydroxypropylmethylcellulose helps to increase viscosity from 400cps up to about 15,000cps as well as increasing lacrimal film stability which helps to increase residence time of drug in the cul-de-sac and thus helps increasing the absorption and eventual bioavailability [88,89].…”

Application of FTIR Spectroscopic Imaging to Study the Effects of Modifying the pH Microenvironment on the Dissolution of Ibuprofen from HPMC Matrices

“…[7][8][9] Less work exists on the use of pH modifiers for modifying the release of weakly acidic drugs. [10][11][12][13] Upon addition of ionic species to the matrix, salts may be formed with oppositely charged drugs of both low solubility 14 and high solubility. While using pHmodified formulations, the pH is adjusted within the tablet matrix; therefore, it is important to understand the behavior of the drug within the matrix.…”