In vitro studies on alendronate sodium incorporated biodegradable alginate beads for implantation

The natural polymers sodium alginate (SA) and chitosan were used for the preparation of SA and chitosan treated sodium alginate (CTSA) beads. Alendronate sodium (AS), which is a potent inhibitor of osteoclast-mediated bone resorption and used for the treatment of bone disorders, was loaded into the SA and CTSA beads prepared for implantation in osteolysis. The beads were prepared by physical crosslinking of calcium ions to SA polymer. The influence of various formulation factors, such as SA concentration, chitosan concentration and the pH of external phase, were investigated. The surface morphology of SA beads examined by scanning electron microscopy (SEM) photographs indicated a porous, rough and also a rigid surface for SA formulations. By increasing the amount of SA, the beads had a more spherical surface characteristic. CTSA formulations had a quite irregular surface characteristic. However, CTSA beads had some cracks and less porous structure on their surface than SA beads. When the amount of chitosan was increased in formulations, the formed beads became non-spherical. Particle sizes of SA beads ranged from 919.06H2.82 -1867.64 ±15.69 \im and CTSA beads from 1018.60±16.73 - 2060.34±17.23 urn. Loading efficacy was found to be 0.70-2.71% for SA beads and 4.01-6.26% for CTSA beads. It was observed that 100% of AS had been released at the end of the sixth hour from SA beads, versus at the end of the twelfth hour from CTSA beads. At a higher SA concentration (6%), AS loading efficacy was found to be increased and, also, the addition of chitosan caused an increase in the drug loading efficacy and particle size of the beads.