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PHARMACOLOGICAL ACTIVITIES - TOXICOLOGY - DRUG INTERACTIONS

Biotin [Vitamin B ] (C H N O S)
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Biotin is attached at the active site of five mammalian enzymes known as carboxylases. Acetyl-
CoA carboxylase I and II catalyze the binding of bicarbonate to acetyl-CoA to form malonyl-CoA
which is required for the synthesis of fatty acids. Pyruvate carboxylase is a critical enzyme in
gluconeogenesis – the formation of glucose from sources other than carbohydrates. Methylcrotonyl-
CoA carboxylase catalyzes an essential step in the catabolism of leucine, an essential amino acid.
Propionyl-CoA carboxylase catalyzes essential steps in the metabolism of certain amino acids,
cholesterol, and odd chain fatty acids (Chapman-Smith & Cronan, 1999; Zempleni & Mock,
1999). Symptoms of biotin deficiency include dried secretions around the eyes, nose and the
angle of the mouth, scaly dermatitis, alopecia, hypersalivation, bloody diarrhea, anorexia, and
emaciation (NRC, 1986).

TOXICOLOGY Toxicity for biotin has not been documented in dogs and cats when administered orally in therapeutic doses.

The LD for repeated (10 day) oral administration in rats was found to be >350 mg/day (EVM, 2002).
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DRUG Anticonvulsant drugs such as primidone and carbamazepine inhibit biotin absorption in the small
INTERACTIONS intestine. Use of valproic acid has been associated with decreased biotinidase activity (Schulpis et
al., 2001; Bowman & Russel, 2006).

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