The aim of the present work was to investigate the swelling behavior and the in vitro release of acemetacin and bovine serum albumin from alginate gel beads crosslinked with Ca2＋ or Ba2＋. The release profiles suggested that the extent of swelling of the alginate beads played an important role in the release of drug. Small drugs are mainly released via diffusion through the alginate gel matrix. Compared with small drugs, large molecule drugs are difficult to diffuse through the pores of the matrix bead until the beads swell to a certain extent to provide enough large pores. The Ba2＋ crosslinked alginate beads showed slower release rate compared with the Ca2＋ crosslinked alginate beads, whether loaded the large molecules or small drugs. In conclusion, the Ba2＋ crosslinked alginate beads are considered more suitable than Ca2＋ crosslinked alginate beads for using as a sustained release vehicle especially for large molecule drugs.
