High molecular weight polyethylene oxides (PEOs) as an alternative to HPMCin controlled release dosage forms

High molecular weight polyethylene oxides (PEOs) have recently been propose d as an alternative to hydroxypropylmethylcellulose (HPMC) in controlled re lease matrix tablets. In this study, we compared the performance of PEO and HPMC polymers when employed in the Geomatrix(R)(1) technology, a versatile , well-known method to achieve extended release of drugs at a constant rate . Four core formulations were prepared, containing a soluble drug (diltiaze m) and, alternatively, PEO or HPMC of two different viscosity grades. These formulations have the same composition except for the polymer employed. Si milarly, four barrier formulations were also prepared, which only differ in the kind of polymer employed. Three-layer Geomatrix(R) systems were then p repared using these core and barrier formulations. The release profiles of the different three-layer systems obtained were compared, to verify if PEO could efficiently replace HPMC in this type of dosage form. The results sho w that slower release rates can be obtained from the plain matrices contain ing HPMC compared to PEG, moreover HPMC, used in the barrier formulations, is generally more efficient in controlling drug release rate in three-layer Geomatrix systems. (C) 2000 Elsevier Science B.V. All rights reserved.