Clinical studies

Study 1

Sixty patients with poor nail quality (brittle, split, or soft nails with a swell factor of <2.5) received either placebo or one 2.5 mg tablet of biotin q.d. in a double-blind placebo-controlled clinical trial. Patients with known nail disease, biotin deficiency, or serious medical conditions were excluded. Concomitant use of other drugs was forbidden. Nail quality was evaluated at baseline and after 3 and 6 months of treatment. Measurements included swell factor (after incubation of the nail in NaOH), transonychial water loss (which correlates with nail plate thickness and is measured via a PeriFlux laser Doppler flowmeter), and subjective ratings of nail quality by the patient and by an observer.

Three patients were excluded from statistical analysis in both the placebo and the biotin groups, leaving a total of 27 evaluable patients in each group. Patients were excluded for a variety of reasons, including study withdrawal; however, none withdrew due to intolerance to study medication. The majority of study participants were female (22 of 27 in the biotin group; 19 of 27 in the placebo group), and ages ranged from 20 to 63 years.

Efficacy Results

Both the objective and subjective measures of nail quality improved after 6 months of treatment in the biotin-treated group. The swell factor and the observer ratings of nail quality improved significantly (P < .05 for both) in the biotin group as compared with the placebo group. Measures of transonychial water loss and self-ratings of nail quality also indicated substantial improvement over the course of biotin treatment, but the changes were not statistically significant when compared with the placebo group.

Improvement in nail quality measured by the swelling of nail keratin in an NaOH medium. Nail swelling was measured on a 10-µm-thick cryosection.

Adapted from Gehring W. Effect of biotin on poor nail quality: a placebo-controlled double-blind clinical study [in German]. Aktuelle Dermatol. 1996;22:20-25. By permission of Georg Thieme Verlag Stuttgart•New York.

Safety Results

Biotin therapy was very well tolerated over the course of this 6-month study. No patients withdrew due to side effects or reported tolerance problems of any kind.

Study 2

Forty-five patients with brittle, splitting, or soft fingernails were treated with biotin (2.5 mg q.d.) for 6 to 10 months in an open-label study. Patients were screened at baseline and determined to be free of any deficiency of zinc, iron, calcium, magnesium, triiodothyronine, thyroxine, folic acid, protein, albumin/globulin ratio, or hemoglobin. Efficacy measures were based on patients’ subjective reports of improvement in nail firmness and reduction in chipping and cracking. Most patients were female (43 of 45) and the mean age was 51.1 ± 16.1 years.

Efficacy Results

Improvement in nail quality was reported by 41 of 45 patients (91%). The mean time to first mention of improvement was 5.5 ± 2.3 months, which approximates the period of time required for nail renewal. The 4 remaining patients reported partial improvement. In addition, 7 of 9 patients with concomitant alopecia or effluvium spontaneously reported improvement of their hair.

Improvement in nail quality after 6 to 10 months of biotin therapy.

Safety Results

Biotin was very well tolerated, and no side effects were reported.

Study 3

The efficacy of biotin for brittle nails was examined via an analysis of retrospective survey data collected on patients who had attended a nail consultation clinic over a 6-month period. Forty-four patients (3 males; 41 females) were identified, but complete information was obtained on only 35 patients. These 35 patients had dry, splitting nails with signs of onychorrhexis or onychoschizia and were offered biotin therapy (2.5 mg q.d.) as treatment. Efficacy assessment was based on patient reports of clinical improvement.

The median patient age was 57 years (range = 21 to 74 years), and duration of symptoms ranged from 2 months to 30 years, with 3 patients claiming their nail condition had always existed. Most patients had tried a variety of treatments without success before receiving biotin therapy. Duration of biotin treatment ranged from 1.5 to 7 months.

Efficacy Results

Clinical improvement was reported by 22 of 35 patients (63%) and was first evident after about 2 months of therapy on average (range = 1 to 4 months). In the group of responders, actual biotin doses ranged from 1.0 to 3.0 mg per day with a mean dose of 2.04 mg per day.

Safety Results

Biotin was well tolerated by this group of patients. Only one patient reported any adverse effect possibly related to biotin. That patient experienced gastrointestinal upset and so discontinued therapy after 6 weeks.

Study 4

Eight women with a diagnosis of brittle nails of unknown origin were treated with 2.5 mg of oral biotin (open label) for 6 to 15 months. Nine nails were collected from these 8 women at baseline and after biotin treatment. Scanning electron microscopy (SEM) was used to evaluate nail thickness, nail splitting, and nail topography at both time points. Ten subjects with normal fingernails served as nontreated controls. SEM evaluations were performed under blinded conditions.

Six of the 8 patients exhibited nail splitting at baseline, and all 8 patients exhibited abnormal nail topography at baseline (irregular and multidirectional orientation of dorsal nail cells). Mean duration of biotin therapy was 9.3 ± 3.6 months.

Efficacy Results

All efficacy parameters improved after biotin treatment. Nail thickness increased by 25% on average, and nail splitting resolved completely in 3 nails and partially in one nail (of the 6 nails with splitting at baseline). Nail topography improved in all 8 patients: 5 nails normalized completely, and 4 nails became more homogeneous in topography.

P<.05, baseline vs posttreatment.

Safety Results

No safety results were reported.