A multiple-unit floating alginate bead drug delivery system with prolonged stomach retention time was developed in this study. The floating alginate beads were prepared by ionic cross-linking method, using CaCO3 as the gas-forming agent. Over 92% of the beads remained floating after 9 h….

http://www.ncbi.nlm.nih.gov/pubmed/24588740

Drug Dev Ind Pharm. 2015 Apr;41(4):674-80. doi: 10.3109/03639045.2014.893355. Epub 2014 Mar 4.