Evaluation of ethylcellulose as matrices for controlled release drug delivery (original) (raw)
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Pakistan journal of pharmaceutical sciences, 2011
The objective of the study was to formulate and evaluate controlled release polymeric tablets of Diclofenac Potassium for the release rate, release patterns and the mechanism involved in the release process of the drug. Formulations with different types and grades of Ethyl Cellulose Ether derivatives in several drug-to-polymer ratios (D:P) were compressed into tablets using the direct compression method. In vitro drug release studies were performed in phosphate buffer (pH 7.4) as dissolution medium by using USP Method-1 (Rotating Basket Method). Similarity factor f2 and dissimilarity factor f1 were applied for checking the similarities and dissimilarities of the release profiles of different formulations. For the determination of the release mechanism and drug release kinetics various mathematical/kinetic models were employed. It was found that all of the Ethocel polymers could significantly slow down the drug release rate with Ethocel FP polymers being the most efficient, especiall...
Purpose: The present study was undertaken to investigate the effect of plastic, hydrophilic and hydrophobic types of polymers and their content level on the release profile of drug from matrix systems. As the physico-chemical nature of the active ingredients influence the drug retarding ability of these polymers, three different drugs were used to evaluate their comparative release characteristics in similar matrices. Methods: Matrix tablets of theophylline, diclofenac sodium and diltiazem HCl using Kollidon SR, Carnauba wax and Hydroxypropyl methylcellulose (HPMC-15cps) were prepared separately by direct compression process. The USP Basket method was selected to perform the dissolution test carried out in 250 ml 0.1N HCl for first two hours and 1000 ml phosphate buffer of pH 6.8 for ten hours. Results: Statistically significant differences were found among the drug release profile from different classes of polymeric matrices. The release kinetics was found to be governed by the type and content of polymer in the matrix system. Higher polymeric content (75%) in the matrix decreased the release rate of drug because of increased tortuosity and decreased porosity. At lower polymeric level (25%), the rate and extent of drug release was elevated. Carnauba wax was found to cause the strongest retardation of drug. On the otherhand, highest drug release was from HPMC matrices while Kollidon SR gave an intermediate release profile between these two polymers. Release rate was also found to be the function of physico-chemical nature of drug molecule. Theophylline and diltiazem HCl, being soluble in nature, released faster than diclofenac sodium from all matrix systems. The release mechanism was explored and explained with biexponential equation. Release profile showed a tendency to follow zero-order kinetics from HPMC matrix systems whereas Fickian (Case I) transport was predominant mechanism of drug release from Kollidon SR matrix system. The mean dissolution time (MDT) was calculated for all the formulations and the highest MDT value was obtained with Carnauba wax for all the drugs under investigation. Conclusions: The results generated in this study showed that the profile and kinetics of drug release were functions of polymer type, polymer level and physicochemical nature of drug. A controlled plasma level profile of drug can be obtained by judicious combination of polymers and modulation of polymer content in the matrix system.
European Journal of Pharmaceutics and Biopharmaceutics, 2006
Experimental design was utilized to simultaneously investigate the effect of varying the type of diluent (insoluble Calcium phosphate or water-soluble arabic gum) and the diluent/matrix ratio on the drug release behaviour from both lipophilic (glyceryl behenate, Compritol) or hydrophilic (hydroxypropylmethylcellulose) matrix tablets. Ketoprofen, theophylline and sodium sulphadiazine were selected as model drugs on the basis of their respectively very low, medium and high water-solubility, in order to evaluate the influence of this parameter as well. The selected response variables were the dissolution efficiency (i.e. the area under the dissolution curve) after one and six hours and the time necessary to dissolve 10% drug. Tablets obtained by direct compression of drug-diluent-matrix ternary mixtures prepared according to the experimental plan provided for by an asymmetric screening matrix, were tested for drug release properties using a USP paddle apparatus. Graphic analysis of the effects allowed identification, for each examined drug, of the formulation factors active on the selected responses and determination of the proper level of the variables to be selected for the response improvement. The different results obtained with the three examined drugs pointed out the role of the drug solubility in determining the influence of formulation parameters on drug release rate from matrix tablets.
2014
ABSTRACT: The objective of this study was to develop a sustained release matrix tablet of aceclofenac using hydroxypropyl methylcellulose (HPMC K15M and HPMC K100M CR) in various proportions as release controlling factor by direct compression method. The powders for tableting were evaluated for angle of repose, loose bulk density, tapped bulk density, compressibility index, total porosity and drug content etc. The tablets were subjected to thickness, weight variation test, drug content, hardness, friability and in vitro release studies. The in vitro dissolution study was carried out for 24 hours using United States Pharmacopoeia (USP) 22 paddle-type dissolution apparatus in phosphate buffer (pH 7.4). The granules showed satisfactory flow properties, compressibility index and drug content etc. All the tablets complied with pharmacopoeial specifications. The results of dissolution studies indicated that the formulations F-2 and F-3 could extend the drug release up to 24 hours. By comp...