Sustained release of ferrous sulfate from polymer-coated gum arabica pellets

Sustained release of ferrous sulfate (FeSO4) from gum arabica pellets has been achieved for 7 h. Release is further sustained for 12 to 600 h by coating the pellets with polyvinyl acetate and ethylene vinyl acetate, respectively. An increase in the amount of gum arabica in the pellets decreases the rate of release due to the gelling property of gum arabica. The gel layer acts as a barrier and retards the rate of diffusion of FeSO4 through the pellet. In coated pellets, an increase in thickness of membrane helps to sustain the release of FeSO4 for a longer duration. Thus, the release of FeSO4 can be sustained for the required duration by adjusting the amount of gum arabica in the pellet and the composition and thickness of polymeric coat. The mechanism of release accordingly varies from Fickian to zero-order and super case II transport.