Original Articles: 2010 Vol: 2 Issue: 4
Formulation and evaluation of gastroretentive tablets of Furosemide (Evaluation based on drug release kinetics and factorial designs)
Gastroretentive floating drug delivery systems (GFDDS) of furosemide, an loop diuretic drug, with an oral bioavailability of only 50% (because of its poor absorption from lower gastrointestinal tract) have been designed and optimized using 3² full factorial design. Hydroxypropyl methyl cellulose of different viscosity grades (K4M and K100M) was used as the polymers and sodium bicarbonate as gas generating agent to reduce floating lag time. The tablets were prepared by direct compression method. Estimation of furosemide in the prepared tablet formulations was carried out with 0.1N HCl and measuring the absorbance at 271 nm. The prepared formulations were further evaluated for hardness, friability, weight variation, drug content uniformity, swelling index, In-vitro drug release pattern, short-term stability and drug excipient interactions. Majority of the designed formulations displayed nearly first order release kientics, releasing more than 80% drug in 10 hours and remained buoyant more than 24 hours. The optimized formulation containing furosemide 80 mg, HPMC (K4M) 100 mg and sodium bicarbonate 30 mg has displayed almost zero order release kinetics with a floating lag time of only 2.9 minutes. This formulation released more than 90% drug in 9 hours. This study proves that GFDDS of furosemide can be designed using HPMC K4M as matrix polymer, which provides nearly zero order release kinetics and thus possible enhancement of oral bioavailability of the drug.