This invention relates to macromolecular complexes useful in drug delivery systems, specifically tri-molecular complexes made between a water-soluble polymer and an acid-insoluble polymer in presence of a bridging molecule. In one aspect, the invention relates to a tri-molecular complex comprising gelatin, acrylic acid/methacrylic acid copolymers, and arginine for use in a soft capsule dosage form. In another aspect, the invention is directed to a tri-molecular complex a hydrophilic, film-forming, water-soluble polymer, a second water-soluble polymer, and a bridging molecule, wherein the second water-soluble polymer is less water-soluble than the hydrophilic, film-forming, water-soluble polymer.
