Edetic Acid

Synonyms: Acidum edeticum; Dissolvine; edathamil; EDTA; ethylenediaminetetraacetic acid; (ethylenedinitrilo)tetraacetic acid; Sequestrene AA; tetracemic acid; Versene Acid

Description:  Edetic acid occurs as a white crystalline powder. 

Chemical Name: N,N-1,2-Ethanediylbis[N-(carboxymethyl)glycine] 

Chelating agent.

• Edetic acid and edetate salts are used in pharmaceutical formulations, cosmetics, and foods as chelating agents.

• They form stable water-soluble complexes (chelates) with alkaline earth and heavy metal ions.

• The chelated form has few of the properties of the free ion, and for this reason chelating agents are often described as ‘removing’ ions from solution; this process is also called sequestering.

• The stability of the metal–edetate complex depends on the metal ion involved and also on the pH.

• The calcium chelate is relatively weak and will preferentially chelate heavy metals, such as iron, copper, and lead, with the release of calcium ions. For this reason, edetate calcium disodium is used therapeutically in cases of lead poisoning.

• Edetic acid and edetates are primarily used as antioxidant synergists, sequestering trace amounts of metal ions, particularly copper, iron, and manganese, that might otherwise catalyze autoxidation reactions.

• Edetic acid and edetates may be used alone or in combination with true antioxidants, the usual concentration employed being in the range 0.005–0.1% w/v.

• Edetates have been used to stabilize ascorbic acid; corticosteroids; epinephrine; folic acid; formaldehyde; gums and resins; hyaluronidase; hydrogen peroxide; oxytetracycline; penicillin; salicylic acid, and unsaturated fatty acids.

• Essential oils may be washed with a 2% w/v solution of edetate to remove trace metal impurities.

• Edetic acid and edetates possess some antimicrobial activity but are most frequently used in combination with other antimicrobial preservatives owing to their synergistic effects

Edetic acid and edetates are incompatible with strong oxidizing agents, strong bases, and polyvalent metal ions such as copper, nickel, and copper alloy. Edetic acid and disodium edetate behave as weak acids, displacing carbon dioxide from carbonates and reacting with metals to form hydrogen.

Edetic acid and edetates are widely used in topical, oral, and parenteral pharmaceutical formulations. They are also extensively used in cosmetics and food products. Edetic acid is generally regarded as an essentially nontoxic and nonirritant material, although it has been associated with doserelated bronchoconstriction when used as a preservative in nebulizer solutions. It has therefore been recommended that nebulizer solutions for bronchodilation should not contain edetic acid

Observe normal precautions appropriate to the circumstances and quantity of material handled. Edetic acid and edetates are mildly irritant to the skin, eyes, and mucous membranes. Ingestion, inhalation, and contact with the skin and eyes should therefore be avoided. Eye protection, gloves, and a dust mask are recommended.

Dipotassium edetate; disodium edetate; edetate calcium disodium; sodium edetate; trisodium edetate.