Author(s): Zempleni J, Mock DM
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Abstract 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.
This article was published in Am J Clin Nutr
and referenced in Journal of Nutrition & Food Sciences