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Sodium Metabisulfit

Sodium metabisulfit digunakan sebagai Aditif Makanan, terutama sebagai pengawet. Hal ini juga digunakan dalam pelayanan kesehatan sebagai agen pembersih. Sodium metabisulfit dan kalium metabisulfit adalah bahan utama dalam tablet Campden, digunakan dalam produksi anggur dan bir. Hal ini umumnya digunakan dalam persiapan bir rumah membersihkan peralatan. Hal ini digunakan sebagai agen pembersih untuk membran reverse osmosis dalam sistem penyulingan air minum. Hal ini juga digunakan untuk menghapus chloramine dari air minumsetelah perawatan (

1 Nonproprietary Names
BP: Sodium Metabisulphite
JP: Sodium Pyrosulfite
PhEur: Sodium Metabisulphite

USP-NF: Sodium Metabisulfite
2 Synonyms
Disodium disulfite; disodium pyrosulfite; disulfurous acidis-odium salt; E223; natrii disulfis; natrii metabisulfis; sodium acidsulfite.
3 Chemical Name and CAS Registry Number
Sodium pyrosulfite [7681-57-4]
4 Empirical Formula and Molecular Weight
Na 2 S 2 O 5 190.1
Sodium metabisulfite contains 24.19% sodium, 42.08% oxy-
gen, and 33.73% sulfur.
5 Structural Formula
See Section 4.
6 Functional Category

Antimicrobial preservative; antioxidant. 7 Applications in Pharmaceutical Formulation or Technology Sodium metabisulfite is used as an antioxidant in oral, parenteral, and topical pharmaceutical formulations, at concentrations of 0.01–1.0% w/v, and at a concentration of approximately 27% w/v in intramuscular injection preparations. Primarily, sodium metabisulfite is used in acidic preparations; for alkaline preparations, sodium sulfite is usually preferred; see Section 18. Sodium metabisulfite also has some antimicrobial activity, which is greatest at acid pH, and may be used as a preservative in oral preparations such as syrups.
In the food industry and in wine production, sodium metabisulfite is similarly used as an antioxidant, antimicrobial preservative, and antibrowning agent. However, at concentrations above about 550 ppm it imparts a noticeable flavor to preparations.
Sodium metabisulfite usually contains small amounts of sodium sulfite and sodium sulfate.
8 Description
Sodium metabisulfite occurs as colorless, prismatic crystals or as a white to creamy-white crystalline powder that has the odor of sulfur dioxide and an acidic, saline taste. Sodium metabisulfite crystallizes from cold water as a hydrate containing seven water molecules.
9 Pharmacopeial Specifications

See Table I.
10 Typical Properties
Acidity/alkalinity pH = 3.5–5.0 for a 5% w/v aqueous solution at 20C. 
Melting point Sodium metabisulfite melts with decomposition at less than 150C.
NIR spectra see Figure 1.
Osmolarity A 1.38% w/v aqueous solution is isoosmotic with
Solubility see Table II.

11 Stability and Storage Conditions
On exposure to air and moisture, sodium metabisulfite is slowly oxidized to sodium sulfate with disintegration of the crystals. Addition of strong acids to the solid liberates sulfur dioxide.
In water, sodium metabisulfite is immediately converted to
sodium (Na+) and bisulfite (HSO3) ions. Aqueous sodium metabisulfite solutions also decompose in air, especially on heating. Solutions that are to be sterilized by autoclaving should be filled into containers in which the air has been replaced with an inert gas, such as nitrogen. The addition of dextrose to aqueous sodium metabisulfite solutions results in a decrease in the stability of the metabisulfite.
 The bulk material should be stored in a wellclosed container, protected from light, in a cool, dry place.

12 Incompatibilities
Sodium metabisulfite reacts with sympathomimetics and other
drugs that are ortho- or para-hydroxybenzyl alcohol derivatives to form sulfonic acid derivatives possessing little or no pharmacological activity. The most important drugs subject to this inactivation are epinephrine (adrenaline) and its derivatives. In addition, sodium metabisulfite is incompatible with chloramphenicol owing to a more complex reaction; it also inactivates cisplatin in solution.
It is incompatible with phenylmercuric acetate when autoclaved in eye drop preparations.

Sodium metabisulfite may react with the rubber caps of multidose vials, which should therefore be pretreated with sodium metabisulfite solution.

13 Method of Manufacture
Sodium metabisulfite is prepared by saturating a solution of sodium hydroxide with sulfur dioxide and allowing crystallization to occur; hydrogen is passed through the solution to exclude air. Sodium metabisulfite may also be prepared by saturating a solution of sodium carbonate with sulfur dioxide and allowing crystallization to occur, or by thermally dehydrating sodium bisulfite.
14 Safety
Sodium metabisulfite is widely used as an antioxidant in oral,
topical, and parenteral pharmaceutical formulations; it is also
widely used in food products.
Although it is extensively used in a variety of preparations,
sodium metabisulfite and other sulfites have been associated with a number of severe to fatal adverse reactions. These are usually hypersensitivity-type reactions and include bronchospasm and anaphylaxis. Allergy to sulfite antioxidants is estimated to occur in 5–10% of asthmatics, although adverse reactions may also occur in nonasthmatics with no history of allergy.
Following oral ingestion, sodium metabisulfite is oxidized to sulfate and is excreted in urine. Ingestion may result in gastric irritation, owing to the liberation of sulfurous acid, while ingestion of large amounts of sodium metabisulfite can cause colic, diarrhea, circulatory disturbances, CNS depression, and death.
In Europe, the acceptable daily intake of sodium metabisulfite and other sulfites used in foodstuffs has been set at up to 3.5 mg/kg body-weight, calculated as sulfur dioxide (SO 2 ). The WHO has similarly also set an acceptable daily intake of sodium metabisulfite, and other sulfites, at up to 7.0 mg/kg body-weight, calculated as sulfur dioxide (SO2 ).

LD 50 (rat, IV): 0.12 g/kg

15 Handling Precautions
Observe normal precautions appropriate to the circumstances and quantity of material handled. Sodium metabisulfite may be irritant to the skin and eyes; eye protection and gloves are recommended. In the UK, the long-term (8-hour TWA) workplace exposure limit for sodium metabisulfite is 5 mg/m3
.16 Regulatory Status
GRAS listed. Accepted for use as a food additive in Europe. Included in the FDA Inactive Ingredients Database (epidural; inhalation; IM and IV injections; ophthalmic solutions; oral preparations; rectal, topical, and vaginal preparations). Included in nonparenteral and parenteral medicines licensed in the UK. Included in the Canadian List of Acceptable Nonmedicinal Ingredients.
17 Related Substances

Potassium metabisulfite; sodium bisulfite; sodium sulfite.
Sodium bisulfite
Empirical formula NaHSO 3
Molecular weight 104.07
CAS number [7631-90-5]
Synonyms E222; sodium hydrogen sulfite.
Appearance White crystalline powder.
Density 1.48 g/cm3
Solubility Soluble 1 in 3.5 parts of water at 20C; 1 in 2 parts of water at 100C; and 1 in 70 parts of ethanol (95%). Freely soluble in glycerol. Aqueous solution is acidic.
Comments Most substances sold as sodium bisulfite contain
significant, variable, amounts of sodium metabisulfite, as the
latter is less hygroscopic and more stable during storage and

shipment. See Section 18.
Sodium metabisulfite is used as an antioxidant at low pH, sodium bisulfite at intermediate pH, and sodium sulfite at higher pH values. A specification for sodium metabisulfite is contained in the Food Chemicals Codex (FCC). 
The EINECS number for sodium metabisulfite is 231-673-0.

sumber : handbok of pharmaceutical excipients; p; 654

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