Formulation and evaluation of floating matrix tablet of Losartan for gastroretentive drug delivery

The prime aim of this research was to develop gastro-retentive delivery system of Losartan which, after oral administration should have the ability to prolong gastric residence time with desired in vitro release profile. Losartan was chosen as a model drug because it is poorly absorbed from the lower gastrointestinal tract. The tablets were prepared by direct compression technique, using various polymers, alone or in combination. The tablets were evaluated for physical characteristics viz. hardness, friability, weight variation, content uniformity, and floating capacity. Further, tablets were evaluated for in vitro release characteristics for 12 hr. Among all the formulations, tablets containing combination of xanthan gum and guar gum showed better floating capacity as well as sustained release of atenolol at the end of 8 hr. The optimized formulation F4 contains the average thickness of 2.12, average hardness of 6.7 and friability of 0.44. The F4 formulation which releases the Losartan in sustained manner in up to 12 hours. The mechanism of release of Losartan from the floating tablets was found to be diffusion couple with erosion. It was concluded that the tablets prepared by polymer HPMC K4M(15%) had efficient floating and sustained release capacity as compared to tablets prepared by using other polymers.