Formulation and evaluation of atorvastatin calcium and nicotinic acid in a bilayer tablet
ABSTRACT Atorvastatin calcium (AT) is used as a dyslipidemic agent. Nicotinic acid (NA) is antihyperlipidemic agent. In the present work development of the rate controlled dosage form for the above drugs were tried the performance characteristics like release kinetics, dissolution rate, particle size of drugs and release retardant and media selection to simulate invivo conditions. Process variables such as impact of hardness, kneading time during granulation are some critical factors found during the development based in the experimental findings. Preformulation study and drug excipients compatibility study was done initially and proceeded further for the formulation according to the results of preformulation study. Wet granulation process was used for both layer of formulation. In the present study HPMC was found to play a great role in controlling release of NA from the matrix system. Accordingly it can be concluded that the final formula is a robust one and theperformance is less likely to be affected by the various factors studied.
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ABSTRACT: The aim of this work was to determine the tensile strength of bilayered tablets made from different grades of microcrystalline cellulose. While these grades are chemically identical, they differ significantly in their particle size distribution and in their mechanical properties such as Young's modulus of elasticity. Tablets were produced in the shape of beams of similar dimensions using uniaxial compression, and solid beams made from one material only were compared with bilayered beams made from various combinations of powders. It was found that in the production of layered tablets it is important for the purpose of quality assurance and control that the upper and lower layer of the compact can be identified. Otherwise, tensile strength measurements will result in large variability depending on which layer faces upwards during the test. Both particle size and Young's modulus of elasticity influenced the overall strength of layered tablets. If the material forming the lower layer was more elastic, then the beam strength was reduced due to tension introduced into the system, acting especially at the layer interface and potentially causing partial or complete delamination. Larger differences in the particle size of the materials forming the tablet layers resulted in an overall reduced compact tensile strength.European journal of pharmaceutical sciences: official journal of the European Federation for Pharmaceutical Sciences 11/2010; 41(3-4):483-8. · 2.61 Impact Factor
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ABSTRACT: A bilayer and floating-bioadhesive drug delivery system exhibiting a unique combination of floatation and bioadhesion to prolong residence in the stomach. Bilayer tablet is new era for the successful development of controlled release formulation along with various features to provide a way of successful drug delivery system. Controlled release (CR) dosage forms have been extensively used to improve therapy with several important drugs. Incorporation of the drug in a controlled release gastro-retentive dosage forms (CR-GRDF) which can remain in the gastric region for several hours would significantly prolong the gastric residence time of drugs and improve bioavailability, reduce drug waste, and enhance the solubility of drugs that are less soluble in high pH environment. Several approaches are currently utilized in the prolongation of the GRT, including floating drug delivery systems (FDDS), swelling and expanding systems, polymeric bioadhesive systems, high-density systems, modified-shape systems and other delayed gastric emptying devices. The floating and bioadhesive drug delivery systems are considerably easy and logical approach. An attempt has been made in this review article to introduce the society to the current technological developments in bilayer and floating- bioadhesive drug delivery system.Journal of Drug Delivery & Therapeutics; 2011. 01/2011;