Biotin - Drug Monograph

Introduction

Biotin (vitamin B7, vitamin H, coenzyme R) is a water-soluble B-complex vitamin that serves as an essential cofactor for carboxylase enzymes involved in critical metabolic processes. While not technically a "drug" in the traditional sense, biotin is widely used as a dietary supplement and has specific medical applications for treating deficiency states and certain genetic disorders.

Mechanism of Action

Biotin functions as a coenzyme for five carboxylases in humans: pyruvate carboxylase, acetyl-CoA carboxylase, propionyl-CoA carboxylase, methylcrotonyl-CoA carboxylase, and holocarboxylase synthetase. These enzymes play crucial roles in:

• Gluconeogenesis
• Fatty acid synthesis
• Amino acid metabolism
• Energy production

Biotin binds covalently to these apocarboxylases through a lysine residue, forming active holoenzymes that catalyze carboxylation reactions essential for metabolic pathways.

Indications

• Treatment of biotin deficiency
• Management of biotinidase deficiency (5-10 mg daily)
• Holocarboxylase synthetase deficiency (10-40 mg daily)

• Hair, skin, and nail health supplementation
• Supportive therapy in peripheral neuropathy
• Management of brittle nail syndrome
• Adjunct in diabetes management (investigational)

Dosage and Administration

• Adults: 30 mcg daily
• Pregnancy: 30 mcg daily
• Lactation: 35 mcg daily

• Biotin deficiency: 5 mg daily orally
• Biotinidase deficiency: 5-10 mg daily orally
• Holocarboxylase synthetase deficiency: 10-40 mg daily orally

• Oral administration with or without food
• Tablets, capsules, or liquid formulations available
• No dosage adjustment required for renal or hepatic impairment

Pharmacokinetics

• Readily absorbed from the proximal small intestine via sodium-dependent multivitamin transporter (SMVT)
• Bioavailability approaches 100% at nutritional doses
• Absorption may be impaired by excessive raw egg white consumption (avidin binding)

• Widely distributed throughout body tissues
• Crosses placenta and enters breast milk
• Protein binding: minimal

• Undergoes limited metabolism
• Functions as a coenzyme without structural modification

• Primarily excreted unchanged in urine
• Elimination half-life: approximately 2 hours
• Small amounts excreted in feces

Contraindications

• Known hypersensitivity to biotin or any component of the formulation
• No other absolute contraindications exist

Warnings and Precautions

• High doses (≥5 mg daily) may interfere with certain laboratory tests:

- Falsely low TSH, FT3, and FT4 values in thyroid function tests - Interference with troponin assays for myocardial infarction - Altered results in some hormone assays

• Patients should inform healthcare providers about biotin supplementation before laboratory testing
• Discontinue high-dose biotin (≥5 mg) at least 48 hours before laboratory testing

Drug Interactions

• Anticonvulsants (carbamazepine, phenytoin, primidone): May decrease biotin levels
• Long-term antibiotic use: May reduce biotin-producing gut flora
• Raw egg white consumption: Avidin binds biotin and prevents absorption

• Immunoassays using biotin-streptavidin technology may yield false results
• Thyroid function tests, cardiac biomarkers, and various hormone assays affected

Adverse Effects

Biotin is generally well-tolerated even at high doses.

• Nausea
• Diarrhea
• Skin rash (rare)

• Anaphylaxis (extremely rare case reports)
• Acneiform eruptions (with very high doses)

No established upper limit or toxicity level due to excellent safety profile.

Monitoring Parameters

• Clinical improvement of deficiency symptoms
• Normalization of organic aciduria in genetic disorders
• Plasma biotin levels (if available)

• Regular assessment of laboratory test interference
• Clinical monitoring for efficacy in indicated conditions
• Periodic evaluation for potential side effects

Patient Education

• Biotin is a water-soluble vitamin essential for metabolic processes
• Take as directed by healthcare provider
• Inform all healthcare providers about biotin supplementation, especially before laboratory testing
• High doses may interfere with important medical tests
• Discontinue high-dose biotin at least 2 days before blood tests unless instructed otherwise
• Store at room temperature away from moisture and heat
• Report any unusual reactions to healthcare provider
• Dietary sources include eggs, nuts, whole grains, and legumes

References

1. National Institutes of Health Office of Dietary Supplements. Biotin Fact Sheet for Health Professionals. 2022. 2. Zempleni J, Wijeratne SSK, Hassan YI. Biotin. Biofactors. 2009;35(1):36-46. 3. Wolf B. Biotinidase deficiency: "if you have to have an inherited metabolic disease, this is the one to have." Genet Med. 2012;14(6):565-575. 4. Elston MS, Sehgal S, Du Toit S, et al. Factitious Graves' Disease Due to Biotin Immunoassay Interference-A Case and Review of the Literature. J Clin Endocrinol Metab. 2016;101(9):3251-3255. 5. FDA Safety Communication: The FDA Warns that Biotin May Interfere with Lab Tests. November 2017. 6. Trüeb RM. Serum Biotin Levels in Women Complaining of Hair Loss. Int J Trichology. 2016;8(2):73-77. 7. Patel DP, Swink SM, Castelo-Soccio L. A Review of the Use of Biotin for Hair Loss. Skin Appendage Disord. 2017;3(3):166-169.