DESIGN OF DOUBLE LAYER TABLETS OF
VALETHAMATE BROMIDE BY USING VARIOUS
POLYMERS BY DIRECT COMPRESSION
METHOD
GÜLGÜN YENER1, AHMAD NASER1, MELIKE ÜNER1*, ASLI
BARLA2
1Istanbul University, Faculty of Pharmacy, Department of
Pharmaceutical Technology, 34116 Beyazıt, Istanbul, Turkey
2Aromsa Besin Aroma ve Katkı Maddeleri Sanayi ve Ticaret Anonim
Şirketi, Gebze 41480 Kocaeli, Turkey
*corresponding author: melikeuner@yahoo.com
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Abstract:

Double layer of valethamate bromide tablets containing 10 mg initial dose and 30 mg maintaining dose in the first and second layers were designed in order to prolong drug release. Xanthan gum, sodium alginate, hydroxypropylmethyl cellulose and carbomer were used for the second matrix layer at various concentrations. Physical controls were
made for characterization of tablets and their powder mixtures. Drug:excipient compatibility was investigated by Fourier Transform Infrared Spectroscopy and Differential Scanning Calorimetry. Results indicated that double layer tablets met compendial requirements in order to provide pharmaceutical quality. Drug release was observed to be faster from sodium alginate tablets followed by xanthan gum, hydroxypropylmethyl cellulose and carbomer at the same concentrations in the second layer (50%) (p<0.01- 0.001). An insignificant difference was determined in drug release from tablets containing carbomer at 40% and 50% (p>0.5). The initial drug release could be obtained within 2 hours except tablets containing 50% carbomer. However, consistent drug release could not
be obtained with sodium alginate tablets that released more than 80% of drug up to 3rd hour. The non-Fickian kinetics correspond to coupled diffusion/polymer relaxation that was clear with HPMC and carbomer tablets. Polymer relaxation resulted in tablet erosion was faster for tablets containing xanthan gum. Swelling and erosion study on tablets were
supported drug release data. Tablets containing carbomer and HPMC were observed to be suitable for prolonged drug delivery. HPMC tablets released about 75% of drug at the 8th hour when tablets containing 30% and 40% carbomer released about 65% of drug.




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