Effect of Polymer Concentration and Viscosity Grade on Atenolol Release from Gastric Floating Drug Delivery Systems

Abstract

Gastroretentive floating drug delivery systems of atenolol, an antihypertensive drug with an oral bioavailability of only 50% (because of its poor absorption from lower gastrointestinal tract) have been designed. Hydroxypropyl methylcelluloses of different viscosity grades (K4M and 50 cps) were used as polymers and sodium bicarbonate as gas generating agent to reduce floating lag time. Tablets were prepared by direct compression method. The prepared formulations were further evaluated for hardness, friability, weight variation, drug content, swelling index, in vitro drug release pattern, short-term stability and drug-excipient interactions. Majority of the designed formulations displayed nearly first order release kinetics releasing more than 75% drug in 10 hours and remained buoyant for more than 24 hours. Drug release data shows that as the proportion and viscosity of polymer increases, drug release decreases. The formulation containing atenolol 50 mg, hydroxypropyl methylcellulose (50 cps) 100 mg and 37 mg sodium bicarbonate (20% w/w of tablet) as gas generating agent, appears to be a promising gastroretentive floating drug delivery system of the drug atenolol, releasing more than 90% of the drug in 10 hours.