Abstract
The effect of three different types of polymer chain structures on the polymer release from hydrophilic matrix tablets was investigated by comparing a synthetic semi-crystalline linear polymer (PEO), a branched amorphous polysaccharide (dextran) and an amorphous substituted cellulose derivative (HPMC). The polymer release rates for tablets containing mixtures of high and low molecular weight grades in different ratios were determined by using a modified USP II method and a SEC-RI chromatography system. The results showed that independent of polymer type: (i) plots of the release versus time had similar shapes, (ii) the release of long and short polymer chains was equal and no fractionation occurred during the release and (iii) the release rate could be related to the average intrinsic viscosity of the polymer mixtures. This confirms the hypothesis that the release rate can be related to a constant viscosity on the surface of the hydrophilic matrix tablet and that it is valid for all the investigated polymers.
Highlights
The use of hydrophilic matrix tablets as drug delivery systems started already during the 60s and is today one of the major extended drug release platforms [1,2,3]
Different polymers can be used as matrix formers; for example polysaccharides like xanthan, dextran, or substituted cellulose derivatives like hydroxypropyl methyl cellulose (HPMC) and hydroxyethyl cellulose or synthetic polymers like poly(ethylene oxide) (PEO) and polyacrylic acid [5,6,7,8,9,10]
For the convenience of the reader, we include corresponding data for PEO, which have been published before [7,14,16]. Both the number-average and the weight-average molecular weights increase with increasing amount of high-molecular weight polymer in the sample
Summary
The use of hydrophilic matrix tablets as drug delivery systems started already during the 60s and is today one of the major extended drug release platforms [1,2,3]. Another finding for PEO matrix tablets was that the release rates of short and long polymer chains were equal [7,14] This means that no fractionation of polymer occurs during the release process within the gel layer. Since no systematic studies relating the polymer release rate to the intrinsic viscosity have been performed for hydrophilic matrix tablets other than PEO [7,14,16] one can ask if the model presented is valid for other polymers.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
