Gastroretentive dosage forms and HPMC K4M.

ABSTRACTThe objective of the study was to formulate and evaluate gastro retentive floating drug delivery tablets of Losartan potassium. It is an orally active non-peptide angiotensin -II receptor antagonist, used in the treatment of hypertension due to mainly blockade of AT1 receptors. The main reason for low therapeutic effectiveness of Losartan potassium is its narrow therapeutic index, poor bioavailability (25-35%), and short biological half life (1.5-2h). Conventional tablets should be administered 3-4 times to maintain plasma drug concentration. So, to increase therapeutic efficacy, reduce frequency of administration sustained release floating matrix tablets of Losartan potassium were prepared. Present study demonstrates the formulation of sustained release floating matrix tablets of Losartan potassium with various grades of hydroxyl propyl methylcellulose to restrict the drug release preferably in upper part of intestine and to improve its bioavailability and to provide constant drug plasma levels thereby improving the patient compliance. Losartan potassium showed maximum absorbance at 256 nm  so absorbance was measured at the same wavelength and found to obey Beer lamberts law in the concentration range of 10-40 mcg/ml. In the pre formulation study of IR spectra of pure drug with the different polymers showed no interaction, Differential scanning calorimetry experiments were carried out to find out the presence of any interaction among drug and the excipients. Pure drug and individual polymers were subjected to the study and no interactions were observed  .12 formulation of sustained release of Losartan potassium were prepared and they were examined for physical properties and appearance like hardness, thickness, weight variation, thickness, hardness, friability uniformity of drug content  floating lag time  floating duration time and in-vitro drug release studies . I n the study all the powder blends showed good flow ability angle of repose below 25.98±0.07°