International Numbering System (INS) for Food Additives: 355
Food additives Europe numbers: E355
Functional Category:
Acidifying agent; buffering agent;flavoring agent.
Applications in Pharmaceutical Formulation
Adipic acid is used as an acidifying and buffering agent in intramuscular, intravenous and vaginal formulations. It is also used in food products as a leavening, pH-controlling, or flavoring agent. Adipic acid has been incorporated into controlled-release formulatio matrix tablets to obtain pH-independent release for both weakly basic(1,2) and weakly acidic drugs.(3,4) It has also been incorporated into the polymeric coating of hydrophilic monolithic systems to modulate the intragel pH, resulting in zero-order release of a hydrophilic drug.(5) The disintegration at intestinal pH of the enteric polymer shellac has been reported to improve when adipic acid was used as a pore-forming agent without affecting release in the acidic media.(6) Other controlled-release formulations have included adipic acid with the intention of obtaining a late-burst release profile.(7)
Description
Adipic acid occurs as a white or almost white, odorless nonhygroscopic crystalline powder. The crystal structure of adipic acid is monoclinic holohedral
Stability and Storage Conditions
Adipic acid is normally stable but decomposes above boiling point. It should be stored in a tightly closed container in a cool, dry place, and should be kept away from heat, sparks, and open flame.
Incompatibilities
Adipic acid is incompatible with strong oxidizing agents as well as strong bases and reducing agents. Contact with alcohols, glycols, aldehydes, epoxides, or other polymerizing compounds can result in violent reactions
Safety
Adipic acid is used in pharmaceutical formulations and food products. The pure form of adipic acid is toxic by the IP route, and moderately toxic by other routes. It is a severe eye irritant, and may cause occupational asthma. LD50 (mouse, IP): 0.28 g/kg(9) LD50 (mouse, IV): 0.68 g/kg LD50 (mouse, oral): 1.9 g/kg LD50 (rat, IP): 0.28 g/kg LD50 (rat, oral): >11 g/kg