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Original Research Communications |
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 µmol) or intravenously (18.4 µmol) to 6 healthy adults in a crossover design with 
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 (
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.
Key Words: Biotin • biotin metabolites • bioavailability • humans • urine • multiple carboxylase deficiency
This article has been cited by other articles:
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B. N Ames, I. Elson-Schwab, and E. A Silver High-dose vitamin therapy stimulates variant enzymes with decreased coenzyme binding affinity (increased Km): relevance to genetic disease and polymorphisms Am. J. Clinical Nutrition, April 1, 2002; 75(4): 616 - 658. [Abstract] [Full Text] [PDF]
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B. Lewis, S. Rathman, and R. McMahon Dietary Biotin Intake Modulates the Pool of Free and Protein-Bound Biotin in Rat Liver J. Nutr., September 1, 2001; 131(9): 2310 - 2315. [Abstract] [Full Text] [PDF]
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K.-S. Wang, G. L. Kearns, and D. M. Mock The Clearance and Metabolism of Biotin Administered Intravenously to Pigs in Tracer and Physiologic Amounts Is Much More Rapid than Previously Appreciated J. Nutr., April 1, 2001; 131(4): 1271 - 1278. [Abstract] [Full Text]
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