Bioavailability of biotin given orally to humans in pharmacologic doses

Am J Clin Nutr. 1999 Mar;69(3):504-8. doi: 10.1093/ajcn/69.3.504.


Background: Patients with carboxylase deficiency are treated with pharmacologic doses of biotin.

Objective: We sought to determine the bioavailability of biotin at pharmacologic doses.

Design: Biotin was administered orally (2.1, 8.2, or 81.9 micromol) or intravenously (18.4 micromol) to 6 healthy adults in a crossover design with > or =2 wk between each biotin administration. Before and after each administration, timed 24-h urine samples were collected. Urinary biotin and biotin metabolites were analyzed by an HPLC avidin-binding assay.

Results: Urinary recoveries of biotin plus metabolites were similar (approximately 50%) after the 2 largest oral doses and the 1 intravenous dose, suggesting 100% bioavailability of the 2 largest oral doses. For unexplained reasons, the apparent recovery of the smallest oral dose was about twice that of the other doses. For all 4 doses, biotin accounted for >50% of the total of biotin and biotin metabolites in urine. Bisnorbiotin (13-23%), biotin-d,l-sulfoxide (5-13%), bisnorbiotin methyl ketone (3-9%), and biotin sulfone (1-3%) accounted for the remainder. The percentage excretion of biotin was greater when biotin was administered intravenously and for the largest oral dose than for the 2 smallest oral doses.

Conclusion: Our data provide evidence that oral biotin is completely absorbed even when pharmacologic doses are administered. Biotin metabolites account for a substantial portion of total urinary excretion and must be considered in bioavailability studies. We speculate that renal losses of biotin (as a percentage of the dose administered) are moderately elevated when pharmacologic doses of biotin are administered.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Administration, Oral
  • Adult
  • Analysis of Variance
  • Biological Availability
  • Biotin / administration & dosage*
  • Biotin / pharmacokinetics*
  • Biotin / urine
  • Cross-Over Studies
  • Dose-Response Relationship, Drug
  • Female
  • Humans
  • Injections, Intravenous
  • Male
  • Micronutrients
  • Multiple Carboxylase Deficiency / drug therapy


  • Micronutrients
  • Biotin