International Numbering System (INS) for Food Additives: 221
Food additives Europe numbers: E221
Functional Category
Antimicrobial preservative; antioxidant.
Applications in Pharmaceutical Formulation
Sodium sulfite is used as an antioxidant in applications similar to those for sodium metabisulfite.(1) It is also an effective antimicrobial preservative, particularly against fungi at low pH (0.1% w/v of sodium sulfite is used). Sodium sulfite is used in cosmetics, food products, and pharmaceutical applications such as parenteral formulations, inhalations, oral formulations, and topical preparations. See also Sodium Metabisulfite
Description
Sodium sulfite occurs as an odorless white powder or hexagonal prisms. Note that the commercially available sodium sulfite is often presented as a white to tan- or pink-colored powder that would not conform to the pharmacopeial specification.
Stability and Storage Conditions
Sodium sulfite should be stored in a well-closed container in a cool, dry, place. In solution, sodium sulfite is slowly oxidized to sulfate by S Sodium Sulfite 669 dissolved oxygen; strong acids lead to formation of sulfurous acid/ sulfur dioxide. On heating, sodium sulfite decomposes liberating sulfur oxides
.Incompatibilities
Sodium sulfite is incompatible with acids, oxidizing agents, many proteins, and vitamin B1. See also Sodium Metabisulfite.
Safety
Sodium sulfite is widely used in food and pharmaceutical applications as an antioxidant. It is generally regarded as relatively nontoxic and nonirritant when used as an excipient.(2,3) However, contact dermatitis and hypersensitivity reactions have been reported.(4,5) The acceptable daily intake for sodium sulfite has been set at up to 350 mg/kg body-weight daily.(6) LD50 (mouse, IP): 0.950 g/kg(7) LD50 (mouse, IV): 0.130 g/kg LD50 (mouse, oral): 0.820 g/kg LD50 (rabbit, IV): 0.065 g/kg LD50 (rabbit, oral): 1.181 g/kg LD50 (rat, IV): 0.115 g/kg