Effects of polymer type, polymer:dırect tablettıng agent ratıo and tablettıng method on verapamıl hydrochlorıde extended release from hydroxypropylmethylcellulose matrıx tablets
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Date
2004
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Abstract
This work has focused on the effects of different hydroxypropylmethylcellulose (HPMC) types and
HPMC:direct tabletting agent (DC-agent) ratio on Verapamil Hydrochloride (VRP HCl) release from
monolayered and three-layered matrix tablets. Investigated polymers were Methocel K100LV, K15M,
K100M and DC-agent was Ludipress® LCE. Eight formulations were prepared as monolayered matrix
tablets while four formulations were prepared as three-layered matrix tablets by direct compression
method. Drug release studies were carried out according to the method given for Delayed Release Articles
in USP XXVII. HPMC types and ratios were found to be effective on drug release. Increasing amount and
viscosity grade of HPMC resulted in a decrease in release of drug from the matrices. Tablets containing
low viscosity grade HPMC at inner and outer layers presented release profiles close to or within the limits
of pharmacopeia. Release data of three-layered matrix tablet (F12) and the reference product (Isoptin®-
KKH) which were in agreement with USP XXVII criteria, were evaluated by mathematical models (zero
order, first order, Higuchi, Hixson-Crowell, Korsmeyer-Peppas), difference factor (f1) and similarity factor
(f2). The kinetics of VRP HCl release from F12 showed best fit to Higuchi model and Isoptin®-KKH well
fitted to zero order kinetic model. F12 and Isoptin®-KKH were both show Anomalous transport mechanism according to their n exponent values. Depending on the results of f1 (5.2) and f2 (71.4) values, F12 and
Isoptin®-KKH were found to be similar with regard to release kinetics.
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Keywords
Verapamil HCl, HPMC, Multi-layered tablets, Direct compression method, Similarity factor