animal studies investigating the efficacy of biotin supplementation on hair quality and quantity were published; in one notable study, 119 dogs with poor coat quality consisting of symptoms including dull coat, brittle hair, and loss of hair due to unknown factors were treated with 5 mg biotin/10 kg body weight/day for 3 to 5 weeks. The study produced notable results; 60% of treated dogs demonstrated complete resolution of all hair and coat symptoms, 31% showed at least partial improvement in hair quality and/or quantity, and only 9% showed no change. 9 These results initially suggested that biotin supplementation may help to treat alopecia or at least improve hair quality in humans as well, however this has yet to be substantiated.4,7 In addition, recent research investigating the potential benefits of biotin supplementation at the molecular level has failed to demonstrate any improvement on hair growth or development. Biotin supplementation appears to have no effect on the proliferation and expression of differentiation specific keratins K1 and K10 in cultures of outer root sheath cells 4,10 and biotin concentrations likewise do not effect the expression of keratin K16, involucrin, and filaggrin as well. 4,10However, not all is grim for biotin’s ability to improve hair quality and quantity, and supplementation may be beneficial for certain patients. It is well known that chronic anticonvulsant therapy with valproic acid can result in a diffuse, nonscarring alopecia.1,11,12,13,14 Valproic acid is a well-established treatment for a wide variety of neurological and psychiatric disorders including various types of seizures and mood disorders.11,14 The pathophysiology underlying the alopecia is thought to be related to an acquired biotin deficiency (both relative and absolute) and this has been corroborated in both animal and human studies.1,4,12,13,15,17 In a Shapirorecently published animal study, alopecia from valproic acid was reversed with biotin supplementation.15 In this study, rats were randomly divided into 4 groups: control, valproic acid (600mg/kd/day) without biotin, valproic acid with biotin supplemented at 6mg/kg/day and valproic acid with biotin supplemented at 0.6mg/kg/day. Alopecia was seen in 40% of the valproic acid group without biotin supplementation, but only 13.3% in either of the biotin supplemented groups. 15 Serum biotin levels in the valproic acid only group were significantly lower than levels seen in the control group, indicating that valproic acid decreases biotin levels, and there were significant decreases in the levels of serum and liver tissue biotinidase in all of the study groups compared with the control group.15Another recently published study investigated serum concentrations of biotin and biotinidase activity in 20 children treated with valproic acid and compared them to age and sex matched controls. Hair loss was observed in 3 patients treated with valproic acid and the alopecia disappeared in all 3 patients after oral administration of biotin for 3 months at 10 mg/day.12 Surprisingly, the authors found no significant differences in the serum levels of biotin and biotinidase activity between patients taking valproic acid and the control group.12 Though apparently conflicting with previous animal studies, serum biotin level measurements in human subjects are notoriously unreliable,1 and that measurement of urinary excretion of biotin and its metabolites are a better predictor of deficiency or excess. 1 In another study, the mean biotinidase activity was assessed in 32 pediatric patients treated with valproic acid and found to be decreased in the first three months of valproic acid use, with a gradual return to baseline after 6 months.16 Similarly, in a different study involving 75 pediatric
