Preparation of alginate beads for floating drug delivery system:: effects of CO2 gas-forming agents

Floating beads were prepared from a sodium alginate solution containing CaCO3 or NaHCO3 as gas-forming agents. The solution was dropped to 1% CaCl2 solution containing 10% acetic acid for CO2 gas and gel formation. The effects of gas-forming agents on bead size and floating properties were investigated. As gas-forming agents increased, the size and floating properties increased. Bead porosity and volume average pore size, as well as the L surface and cross-sectional morphology of the beads were examined with Mercury porosimetry and Scanning Electron Microscopy. NaHCO3 significantly increased porosity and pore diameter than CaCO3. Incorporation of CaCO3 into alginate Solution resulted in smoother beads than those produced with NaHCO3. Gel strength analysis indicated that bead strength decreased with increasing gas-forming agent from 9 to 4 N. Beads incorporating CaCO3 exhibited significantly increased get strength over control and NaHCO3-containing samples. Release characteristics of riboflavin as a model drug were Studied in vitro. Release rate of riboflavin increased proportionally with addition of NaHCO3. However, increasing weight ratios of CaCO3 did not appreciably accelerate drug release. The results of these Studies indicate that CaCO3 is superior to NaHCO3 us a gas forming agent in alginate bead preparations. The enhanced buoyancy and sustained release properties of CaCO3-containing beads make them an excellent candidate for floating drug dosage systems (FDDS). (C) 2002 Published by Elsevier Science B.V.