Formulation and evaluation of once a day bilayer floating tablet of antihypertensive drug involving dissolution enhancement approach

Valsartan, a widely prescribed anti-hypertensive drug which is an angiotensin II type 1 receptor antagonists belongs to BCS class IΙ. It shows absorption window in stomach area, which makes it a good candidate for gastro retentive dosage forms. The objective of the study is to develop a bilayer floating tablets of Valsartan to increase the Bioavailability of Valsartan by increasing dissolution and give sustained release action upto 24hrs by Single unit dosage. Valsartan:β-cyclodextrin complex was prepared by kneading method. Bilayer Floating Tablets of Valsartan its inclusion complex with β-cyclodextrin (βCD) were formulated by Direct compression method. The immediate release layer comprised of Sodium starch glycholate as a super disintigrant and sustained release layer comprised of Ethyl cellulose and HPMC K100M as release retarding polymers to control the drug release and restrict the region of drug release to stomach. A 32 factorial design was applied to optimize the drug release profile. A 5.3 fold increase in the dissolution efficiency of Valsartan was observed with Valsartan:βCD in the ratio of 1:1. Trial batches of IR layer tablet shows best result with SSG 6%. After application of factorial design it was found that formulation F6 (30% HPMC K100M & 6% Ethyl Cellulose) release 98.44% of Valsartan in 24 hrs. with desired floating lag time (236 sec.) and constantly floated on dissolution medium for upto 24 hrs. From the study it concluded that a sustained release bilayer dosage form of Valsartan for 24hrs can be formulated using dissolution enhancement approach.
Author(s): Nirav D. Solanki, Shreeraj Shah, Jaymin Patel and Pratik Upadhyay

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