Sodium Metabisulphite

Usage

Sodium Metabisulphite is primarily used as a preservative, antioxidant, and disinfectant. It is not a typical pharmaceutical agent classified under categories such as antibiotic, analgesic, etc. It’s used in various medical settings, including as a component in some medications, for sterilizing medical equipment, for water purification systems and in medical laboratory settings. Its mechanism of action involves releasing sulfur dioxide (SO2) when dissolved in water, creating an environment hostile to microorganisms. It also acts as an antioxidant, preventing oxidation of other substances.

Alternate Names

• Sodium pyrosulfite
• Disodium disulfite
• Disodium pyrosulfite
• Disulfurous acid, disodium salt
• Pyrosulfurous acid, disodium salt

How It Works

Pharmacodynamics: Sodium metabisulfite’s primary effect is antimicrobial, achieved by releasing SO2. The SO2 disrupts microbial metabolic processes, leading to their inactivation or death. It acts as an antioxidant and reducing agent in various applications.

Pharmacokinetics: When ingested, sodium metabisulfite is rapidly metabolized in the liver to sulfate and excreted primarily in the urine. Topical exposure may lead to limited systemic absorption.

Mode of Action: The antimicrobial activity is based on the release of sulfur dioxide, which interferes with several key microbial metabolic processes.

Elimination pathways: Renal excretion of sulfate is the primary route of elimination after metabolism in the liver.

Dosage

Sodium metabisulfite dosing is dependent on its intended use (e.g., as a preservative in a drug formulation, for equipment sterilization, or water purification) and thus varies widely. There isn’t a standardized dosing regimen for direct medicinal use in patients. Information found describes its role as an excipient in some medications. The sources provided mention the following uses and dosages, though their medical relevance is not explicitly confirmed.

Sterilizing of equipment: 1 tablespoon per 5 liters of water (non-medical application)

Preserving juice: 1/16 teaspoon per gallon of juice.

Side Effects

Common Side Effects

• Skin irritation
• Eye irritation
• Respiratory irritation (coughing, wheezing, shortness of breath) in sensitive individuals, especially asthmatics

Rare but Serious Side Effects

• Severe allergic reactions (anaphylaxis)
• Severe bronchospasm

Adverse Drug Reactions (ADR)

• Anaphylaxis (rare but potentially life-threatening)

Contraindications

• Known hypersensitivity to sulfites

Drug Interactions

• May interact with certain medications due to its antioxidant and reducing properties
• Medications sensitive to pH changes or oxidation
• Drugs that may cause a disulfiram-like reaction (e.g. metronidazole)

Pregnancy and Breastfeeding

Limited data available suggest no known significant risks. However, prudence is advised.

Drug Profile Summary

• Mechanism of Action: Antimicrobial (releases SO2), antioxidant.
• Side Effects: Skin/eye irritation, respiratory irritation (in sensitive individuals), rarely anaphylaxis.
• Contraindications: Sulfite hypersensitivity.
• Drug Interactions: Drugs sensitive to pH/oxidation; disulfiram-like reactions.
• Pregnancy & Breastfeeding: Limited data, caution advised.

Precautions

• Pre-screening for sulfite allergy.
• Caution in asthmatics and those with respiratory conditions.
• Avoid direct contact with skin and eyes.
• Use in well-ventilated areas to avoid inhaling SO2 fumes.

FAQs (Frequently Asked Questions)

Q1: What is the primary use of sodium metabisulfite in a medical context?

A: Primarily as a preservative, antioxidant, disinfectant, and sterilizing agent, rather than a direct therapeutic medication.

Q2: How does sodium metabisulfite work as an antimicrobial?

A: It releases sulfur dioxide (SO2) when dissolved in water, which disrupts microbial metabolism.

Q3: What are the common side effects?

A: Skin and eye irritation, respiratory irritation (especially in asthmatics).

Q4: What is the most serious potential adverse reaction?

A: Anaphylaxis (rare but life-threatening).

Q5: Who should avoid exposure to sodium metabisulfite?

A: Individuals with a known sulfite hypersensitivity.

Q6: Are there any drug interactions to be aware of?

A: May interact with drugs sensitive to pH or oxidation, or those that cause disulfiram-like reactions.

Q7: Is it safe to use during pregnancy or breastfeeding?

A: Limited data are available, caution is advised.

Q8: What precautions should be taken when handling sodium metabisulfite?

A: Avoid direct contact, use in well-ventilated areas, and pre-screen for sulfite allergy.

Q9: Is Sodium metabisulfite used as a standalone medication to treat any specific disease?

A: No, it’s primarily used as an excipient in some medications for its preservative or antioxidant properties, and less so as a disinfectant or sterilizing agent. It is not a direct therapeutic medication for any particular disease.

Q10: What is the Acceptable Daily Intake (ADI) for sodium metabisulfite?

A: 0.7 mg of SO2 equivalent per kilogram of body weight, as per EU/FAO recommendations.