Name: Sodium Citrate Dihydrate
CAS No: Trisodium 2-hydroxypropane-1,2,3-tricarboxylate dihydrate [6132-04-3]
BP: Sodium Citrate JP: Sodium Citrate Hydrate PhEur: Sodium Citrate USP: Sodium Citrate
Citric acid trisodium salt; E331; natrii citras; sodium citrate tertiary; trisodium citrate
Trisodium 2-hydroxypropane-1,2,3-tricarboxylate dihydrate [6132-04-3]
C6H5Na3O72H2O 294.10
Sodium citrate, as either the dihydrate or anhydrous material, is widely used in pharmaceutical formulations; see Table I. It is used in food products, primarily to adjust the pH of solutions. It is also used as a sequestering agent. The anhydrous material is used in effervescent tablet formulations.(1) Sodium citrate is additionally used as a blood anticoagulant either alone or in combination with other citrates such as disodium hydrogen citrate. Therapeutically, sodium citrate is used to relieve the painful irritation caused by cystitis, and also to treat dehydration and acidosis due to diarrhea
Sodium citrate dihydrate consists of odorless, colorless, monoclinic crystals, or a white crystalline powder with a cooling, saline taste. It is slightly deliquescent in moist air, and in warm dry air it is efflorescent. Although most pharmacopeias specify that sodium citrate is the dihydrate, the USP 32 states that sodium citrate may be either the dihydrate or anhydrous material
See Table II.
Acidity/alkalinity pH = 7.0–9.0 (5% w/v aqueous solution) Density (bulk) 1.12 g/cm3 Density (tapped) 0.99 g/cm3 Density (true) 1.19 g/cm3 Melting point Converts to the anhydrous form at 1508C. NIR spectra see Figure 1. Osmolarity A 3.02% w/v aqueous solution is iso-osmotic with serum. Particle size distribution Various grades of sodium citrate dihydrate with different particle sizes are commercially available. Solubility Soluble 1 in 1.5 of water, 1 in 0.6 of boiling water; practically insoluble in ethanol (95%).
Sodium citrate dihydrate is a stable material. Aqueous solutions may be sterilized by autoclaving. On storage, aqueous solutions may cause the separation of small, solid particles from glass containers. The bulk material should be stored in an airtight container in a cool, dry place.
Aqueous solutions are slightly alkaline and will react with acidic substances. Alkaloidal salts may be precipitated from their aqueous or hydro-alcohol solutions. Calcium and strontium salts will cause precipitation of the corresponding citrates. Other incompatibilities include bases, reducing agents, and oxidizing agents.
Sodium citrate is prepared by adding sodium carbonate to a solution of citric acid until effervescence ceases. The resulting solution is filtered and evaporated to dryness.
After ingestion, sodium citrate is absorbed and metabolized to bicarbonate. Although it is generally regarded as a nontoxic and nonirritant excipient, excessive consumption may cause gastrointestinal discomfort or diarrhea. Therapeutically, in adults, up to 15 g daily of sodium citrate dihydrate may be administered orally, in divided doses, as an aqueous solution to relieve the painful irritation caused by cystitis. Citrates and citric acid enhance intestinal aluminum absorption in renal patients, which may lead to increased, harmful serum aluminum levels. It has therefore been suggested that patients with renal failure taking aluminum compounds to control phosphate absorption should not be prescribed citrate- or citric acid-containing products.(2)
Observe normal precautions appropriate to the circumstances and quantity of material handled. Sodium citrate dihydrate dust may be irritant to the eyes and respiratory tract. Eye protection and gloves are recommended. Sodium citrate should be handled in a wellventilated environment or a dust mask should be worn
GRAS listed. Accepted for use as a food additive in Europe. Included in the FDA Inactive Ingredients Database (inhalations; injections; ophthalmic products; oral solutions, suspensions, syrups and tablets; nasal, otic, rectal, topical, transdermal, and vagina preparations). Included in nonparenteral and parenteral medicines licensed in the UK. Included in the Canadian List of Acceptable Non-medicinal Ingredients.
Anhydrous sodium citrate; citric acid monohydrate. Anhydrous sodium citrate Empirical formula C6H5Na3O7 Molecular weight 258.07 CAS number [68-04-2] Synonyms anhydrous trisodium citrate; citric acid trisodium salt anhydrous; trisodium 2-hydroxy-1,2,3-propanetricarboxylic acid. Appearance Colorless crystals or a white crystalline powder. Safety LD50 (mouse, IP): 1.36 g/kg(3) LD50 (mouse, IV): 0.17 g/kg LD50 (rabbit, IV): 0.45 g/kg LD50 (rat, IP): 1.55 g/kg
Each gram of sodium citrate dihydrate represents approximately 10.2 mmol of sodium and 3.4 mmol of citrate. Each gram of anhydrous sodium citrate represents approximately 11.6 mmol of sodium and 3.9 mmol of citrate. The EINECS number for sodium citrate is 200-675-3. The PubChem Compound ID (CID) for sodium citrate dihydrate is 71474