Vitamin B2

Usage

• Medical Conditions: Vitamin B2, also known as riboflavin, is prescribed for preventing and treating riboflavin deficiency (ariboflavinosis). It may also be used for migraine prophylaxis and in patients with hyperhomocysteinemia. Riboflavin deficiency can manifest as angular cheilitis, cheilosis, glossitis, seborrheic dermatitis, and corneal vascularization.
• Pharmacological Classification: Vitamin, water-soluble vitamin, B vitamin.
• Mechanism of Action: Riboflavin is a precursor to flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). These coenzymes are essential for numerous enzymatic reactions involved in energy production, cellular function, growth and development, and the metabolism of fats, drugs, and steroids. They act as electron carriers in oxidation-reduction reactions within the electron transport chain.

Alternate Names

• Riboflavin
• Vitamin G

How It Works

• Pharmacodynamics: Riboflavin, through its active metabolites FMN and FAD, acts as a coenzyme in various metabolic pathways, including carbohydrate, protein, and fat metabolism. It contributes to cellular respiration and energy production. It also plays a role in maintaining healthy skin, eyes, and nervous system function.
• Pharmacokinetics:
  • Absorption: Absorbed primarily in the proximal small intestine. Absorption is saturable, with limited absorption of doses exceeding 27 mg.
  • Metabolism: Converted to FMN and FAD in various tissues.
  • Elimination: Excreted primarily in urine, giving it a characteristic bright yellow color. Excess riboflavin is not stored and gets readily excreted.

Dosage

Standard Dosage

Adults:

• Riboflavin Deficiency: 5-30 mg/day orally, divided into doses.
• Migraine Prophylaxis: 400 mg/day orally.
• Dietary Supplementation (RDA):
  • Males: 1.3 mg/day
  • Females: 1.1 mg/day
  • Pregnant: 1.4 mg/day
  • Lactating: 1.6 mg/day

Children:

• RDA:
  • 0-6 months: 0.3 mg/day
  • 7-12 months: 0.4 mg/day
  • 1-3 years: 0.5 mg/day
  • 4-8 years: 0.6 mg/day
  • 9-13 years: 0.9 mg/day
  • 14-18 years (boys): 1.3 mg/day
  • 14-18 years (girls): 1.0 mg/day

Special Cases:

• Elderly Patients: No specific dosage adjustments are generally necessary, but assessment of dietary intake and potential need for supplementation is essential.
• Patients with Renal Impairment: No dose adjustment is usually required.
• Patients with Hepatic Dysfunction: Impaired riboflavin absorption is possible, necessitating careful monitoring and potential supplementation.

Clinical Use Cases

• Dosage recommendations for specific medical settings like intubation, surgical procedures, mechanical ventilation, ICU use, and emergency situations are not specifically established for riboflavin. Its use is primarily directed towards preventing and correcting nutritional deficiency rather than as a direct treatment for acute medical interventions.

Side Effects

Common Side Effects

• Bright yellow discoloration of urine.

Rare but Serious Side Effects

• Rare instances of diarrhea and nausea have been reported with high doses.

Long-Term Effects

• No known serious long-term effects are associated with riboflavin supplementation within recommended dosages.

Contraindications

• No absolute contraindications to riboflavin use exist.

Drug Interactions

• Certain medications may reduce riboflavin absorption or metabolism, including:
  • Antipsychotics (e.g., chlorpromazine)
  • Barbiturates
  • Tricyclic antidepressants
• Riboflavin can decrease the effectiveness of certain antibiotics, including:
  • Streptomycin
  • Erythromycin
  • Tetracyclines
• Alcohol, caffeine, and certain minerals (e.g., iron, zinc, copper) may interfere with riboflavin absorption.

Pregnancy and Breastfeeding

• Riboflavin is considered safe during pregnancy and breastfeeding at recommended daily allowances (RDAs).
• Higher doses during pregnancy should be used with caution and under medical supervision.

Drug Profile Summary

• Mechanism of Action: Precursor to FMN and FAD, essential coenzymes for energy metabolism and various cellular processes.
• Side Effects: Generally well-tolerated; bright yellow urine is a common and harmless effect. Diarrhea and nausea may occur with high doses.
• Contraindications: None known.
• Drug Interactions: Antipsychotics, barbiturates, tricyclic antidepressants, certain antibiotics, alcohol, caffeine, iron, zinc, copper.
• Pregnancy & Breastfeeding: Safe at RDA levels; higher doses should be used cautiously during pregnancy.
• Dosage: See detailed dosage section above.
• Monitoring Parameters: Clinical signs and symptoms of riboflavin deficiency; urine color.

Popular Combinations

• Riboflavin is frequently included in B-complex vitamin preparations and multivitamins.
• Combined supplementation with other B vitamins (e.g., B6, B12, folate) can be beneficial in some cases, such as hyperhomocysteinemia.

Precautions

• Patients with malabsorption syndromes or liver disease may require higher doses or parenteral administration.

FAQs (Frequently Asked Questions)

Q1: What is the recommended dosage for Vitamin B2?

A: The recommended dietary allowance for adults is 1.3 mg/day for males and 1.1 mg/day for females. Higher doses may be used therapeutically for riboflavin deficiency (5-30 mg/day) or migraine prophylaxis (400 mg/day). Pediatric doses vary with age.

Q2: What are the common signs of riboflavin deficiency?

A: Angular cheilitis (inflammation at the corners of the mouth), cheilosis (cracked lips), glossitis (inflamed tongue), seborrheic dermatitis, weakness, and corneal vascularization.

Q3: Does riboflavin interact with any medications?

A: Yes, riboflavin can interact with certain medications like antipsychotics, barbiturates, tricyclic antidepressants, and some antibiotics. It can also interact with alcohol, caffeine, and some minerals like iron, zinc, and copper.

Q4: Can pregnant or breastfeeding women take riboflavin?

A: Riboflavin is generally considered safe during pregnancy and breastfeeding at the RDA levels. Higher doses should be taken with caution and under medical supervision during pregnancy.

Q5: Are there any long-term effects of taking riboflavin supplements?

A: No known serious long-term side effects are associated with riboflavin supplementation at recommended dosages.

Q6: How is riboflavin metabolized and eliminated from the body?

A: Riboflavin is converted to its active coenzyme forms, FMN and FAD, and then primarily excreted in the urine.

Q7: Is riboflavin treatment effective for all types of migraines?

A: While riboflavin has shown some efficacy in migraine prophylaxis, it may not be effective for all individuals or all types of migraines. Individual responses can vary.

Q8: Are there any dietary sources of riboflavin?

A: Yes, good dietary sources include milk, cheese, liver, meat, eggs, green leafy vegetables, almonds, and fortified cereals.

Q9: What is the role of riboflavin in cellular function?

A: Riboflavin is crucial for cellular function primarily through its roles in energy production (as FMN and FAD in the electron transport chain), redox reactions, and the metabolism of fats, drugs, and steroids.

Q10: How long does it take to see the benefits of riboflavin for migraine prevention?

A: It may take up to three months of consistent riboflavin supplementation at therapeutic doses to see optimal results for migraine prevention.