Herein, the controlled release of etidronic acid (hydroxyethylidene-bis(phosphonic) acid), an important drug for osteoporotic conditions, immobilized onto cationic polymeric matrices, such as polyethyleneimine (PEI) or cationic inulin (CATIN) is reported. Several CATIN- and PEI-etidronate composites have been synthesized at various pH regions and characterized. Tablets with starch as the excipient containing the active ingredient (polymer-etidronate composite) were prepared, and the controlled release of etidronate was studied at aqueous solutions of pH 3 (to mimick the pH of the stomach) for 8 h. All studied composites showed a delayed etidronate release in the first 4 h, compared to the "control" (a tablet containing only starch and etidronic acid, without the polymer).