Sodium thiosulfate

• BPSodium Thiosulfate
• JPSodium Thiosulfate Hydrate
• Ph. Eur.Sodium Thiosulfate
• USP–NFSodium Thiosulfate

Disodium thiosulfate pentahydrate; hypo; natrii thiosulfas; sodium hyposulfite; thiosulfuric acid disodium salt

Disodium thiosulfate pentahydrate · [7772-98-7]

UNII L0IYT1O31N · PubChem CID 24477

Na2S2O3·5H2O (pentahydrate); Na2S2O3 (anhydrous) · 248.17 (pentahydrate); 158.11 (anhydrous)

Antioxidant, chelating agent

Typical concentrations: — · Dosage forms: Sterile (parenteral/ophthalmic)

As an excipient, sodium thiosulfate is used as an antioxidant and reducing agent in some injections and other preparations, generally at low concentrations. It is better known as an active ingredient: intravenously as an antidote in cyanide poisoning (with sodium nitrite) and to reduce cisplatin-induced ototoxicity, topically for pityriasis versicolor, and in analytical and antiseptic practice to neutralise iodine and chlorine.

Large, colourless, transparent crystals or a coarse crystalline powder, odourless, with a cooling and slightly bitter, saline taste. The crystals effloresce in warm, dry air and are slightly deliquescent in moist air.

Melting point

the pentahydrate melts in its water of crystallisation at about 48 °C and loses it at about 100 °C

Solubility

very soluble in water; practically insoluble in ethanol

pH

aqueous solutions are approximately neutral to slightly alkaline

Stable in the solid state when stored in an airtight container. Aqueous solutions decompose slowly, especially if acidic, with deposition of sulfur; they are stabilised by a small amount of alkali and can be sterilised by autoclaving.

Decomposed by acids with liberation of sulfur dioxide and precipitation of sulfur. Incompatible with oxidising agents, iodine (which it reduces) and salts of heavy metals such as lead, mercury and silver, with which it forms complexes or precipitates.

Prepared by boiling a solution of sodium sulfite with sulfur, or as a by-product of sulfide dye and sulfur-removal processes, and purified by crystallisation of the pentahydrate.

Of low toxicity; it is poorly absorbed orally and acts as an osmotic laxative in large doses. Intravenous use in high doses can cause hypotension, nausea, vomiting and osmotic effects, but excipient levels are not associated with significant toxicity.

Observe normal precautions for the quantity handled. Eye protection and gloves are recommended.

GRAS listed. Included in the FDA Inactive Ingredient Database (injections and other preparations) and in medicines licensed in Europe.

Sodium metabisulfite; sodium sulfite; sodium formaldehyde sulfoxylate.

Keep solutions at neutral to slightly alkaline pH to prevent sulfur deposition. The pentahydrate contains about 36% water, which must be allowed for when the anhydrous equivalent is specified.