Preparation and characterization of Ca-alginate microspheres by a new emulsification method

The preparation and characterization of Ca-alginate microspheres obtained by a new procedure from alginic acid, treated with an excess of NaOH and subsequently with a very concentrated solution of CaCl2 are described. The produced particles have a spherical shape with an average diameter of 350 mu m. The particles show a relative dense and homogeneous internal structure in comparison with previously reported alginate microcapsules (the bulk density being 0.47 g/cm(3)), consequently the particle matrix is characterized by a high density of charged carboxylic groups. Particles produced with a contact time of 1 h showed a degree of crosslinking of 54%. Microspheres have a good stability, and despite of very low degree of swelling, they have a good solvents regain, and an excellent ionic binding capacity of cationic drugs. After preparation the beads were loaded by ionic complexation with an antitumor aromatic tetramidine. In addition, the in vitro release of drug has been studied. (C) 1998 Elsevier Science B.V. All rights reserved.