Formulation Development and Evaluation of Gastroretentive Bilayer Floating Tablets of Simvastatin and Telmisartan
The objective of this present investigation is to design and evaluate the gastroretentive bilayer floating tablets of Simvastatin as controlled release and Telmisartan as immediate release. The combination therapy of Telmisartan and Simvastatin is useful in serious cardiovascular adverse effect such as hypertension, congestive heart failure and exacerbation of angina which may occur along with increasing cholesterol level in the blood, while the fixed dose combination remain the preferable choice to the patient as compared to the individual dosage form. Bi-layer tablet is suitable for sequential release of two drugs in combination, two incompatible substances and also for controlled release of drug. The bilayer tablets are prepared using different super disintegrants like Sodium Starch Glycolate, Cross Carmellose Sodium, Crospovidone for Telmisartan immediate release and xanthan gum, guar gum and HPMC K4M for Simvastatin controlled release. Sodium Bicarbonate is used as a gas generating agent. The precompression parameters like angle of repose, bulk density, tapped density; compressibility index and hausner’s ratio were studied. The tablets were characterized by physical and chemical parameters such as tablet Uniformity of weight, thickness, hardness, diameter, friability, drug content, swelling index and In vitro drug release. The optimized formulation based on all the parameter T-3(Crospovidone) was selected for immediate release layer, S-5(Xanthan gum and HPMC K4M) for controlled release layer and bilayer tablets were prepared. The dissolution data was subjected to various release kinetic models to understand the mechanism of drug release.