International Numbering System (INS) for Food Additives: 172
Food additives Europe numbers: E172
Functional Category
Colorant.
Applications in Pharmaceutical Formulation
Iron oxides are widely used in cosmetics, foods, and pharmaceutical applications as colorants and UV absorbers.(1–3) As inorganic colorants they are becoming of increasing importance as a result of the limitations affecting some synthetic organic dyestuffs. However, iron oxides also have restrictions in some countries on the quantities that may be consumed, and technically their use is restricted because of their limited color range and their abrasiveness.
Description
Iron oxides occur as yellow, red, black, or brown powder. The color depends on the particle size and shape, and crystal structure.
Stability and Storage Conditions
Iron oxides should be stored in well-closed containers in a cool, dry place.
Incompatibilities
Iron oxides have been reported to make hard gelatin capsules brittle at higher temperatures when the residual moisture is 11–12%. This factor affects the use of iron oxides for coloring hard gelatin capsules, and will limit the amount that can be incorporated into the gelatin material.
Safety
Iron oxides are widely used in cosmetics, foods, and oral and topical pharmaceutical applications. They are generally regarded as nontoxic and nonirritant excipients. The use of iron oxide colorants is limited in some countries, such as the USA, to a maximum ingestion of 5 mg of elemental iron per day. LD50 (mouse, IP): 5.4 g/kg(5) LD50 (rat, IP): 5.5 g/kg