Effect of the formulation on the in-vitro release of propranolol from gellan beads

Gellan gum beads of propranolol hydrochloride, a hydrophilic model drug, we re prepared by solubilising the drug in a dispersion of gellan gum and then dropping the dispersion into calcium chloride solution. The droplets forme d gelled beads instantaneously by ionotropic gelation. Major formulation an d process variables which might influence the preparation of the beads and the drug release from gellan gum beads were studied. Very high entrapment e fficiencies were obtained (92%) after modifying the pH of both the gellan g um dispersion and the calcium chloride solution. The beads could be stored for 3 weeks in a wet or dried state without modification of the drug releas e. Oven-dried beads released the drug somewhat more slowly than the wet or freeze-dried beads. The drug release from oven-dried beads was slightly aff ected by the pH of the dissolution medium. Gellan gum could be a useful car rier for the encapsulation of fragile drugs and provides new opportunities in the held of bioencapsulation. (C) 1999 Elsevier Science B.V. All rights reserved.