PHARMACOLOGY UPDATE
Tavaborole Topical Solution, 5% (Kerydin¢â)
By William T. Elliott, MD, FACP, and James Chan, PharmD, PhD
Dr. Elliott is Chair, Formulary Committee, Northern California Kaiser Permanente; and Assistant Professor of Medicine, University of California, San Francisco. Dr. Chan is Pharmacy Quality and Outcomes Manager, Kaiser Permanente, Oakland, CA
Drs. Elliott and Chan report no financial relationships relevant to this field of study.
The first oxaborole antifungal has been approved for the treatment of fungal toenail infection. Tavaborole is a topical solution that is applied daily to the infected nail. It is marketed by Anacor Pharmaceuticals as Kerydin¢â.
INDICATIONS
Tavaborole is indicated for the treatment of onychomycosis of the toenail due to Trichophyton rubrum or Tricophyton mentagrophytes.1
DOSAGE
Apply to the affected toenail (entire toenail surface and under the tip) once daily for 48 weeks.1 Tavaborole is available as 5% solution (10 mL).
POTENTIAL ADVANTAGES
Resistance to tavaborole after repeated exposure has not been demonstrated.1
POTENTIAL DISADVANTAGES
Cure rate (complete or almost complete) is low, 15-18%, after 48 weeks of application.1
COMMENTS
The efficacy and safety of tavaborole was evaluated in two double-blind, randomized, vehicle-controlled trials.1 Subjects with 20-60% involvement of the toenail without dermatophyoma or lunula involvement were randomized to tavaborole applied once daily or vehicle for 48 weeks. The primary efficacy endpoint was assessed at 52 weeks. This was defined as complete cure (complete clear nail and mycological cure). Secondary endpoints included complete or almost complete cure (mycological cure and ¡Â 10% involvement in affected toenail) and mycological cure. Complete cure was observed in 6.5% in study one and 9.1% in the second trial. The values for vehicle were 0.5% and 1.5%, respectively. The percentages for complete or almost complete cure were 15.3% and 17.9% vs 1.5% and 3.9%, respectively. The percentages for mycological cure were 31.1% and 35.9% vs 7.2% and 12.2%, respectively. Adverse events were minimal (< 3%); these include application site exfoliation, ingrown toenail, site erythema, and dermatitis.1
CLINICAL IMPLICATIONS
Onychomycosis is a common fungal infection of the nail and nail bed. Treatment choice depends on the number of nails affected and severity of the infection. Systemic treatment is recommended for more serious forms, while superficial onychomycosis and infections limited to distal nails can be treated with topical agents. Currently available agents include ciclopirox olamine 8% and efinaconazole 10%.2 There are currently no published studies comparing tavaborole and ciclopirox or efinaconazole; however, in similar study design and duration of treatment in subjects with similar degree of nail involvement, the complete cure rate for ciclopirox was 5.5% and 8.5% in two studies compared to 0.9% and 0% for the vehicle.3 For efinaconazole, cure rates were 15.2% and 17.8% compared to 5.5% and 3.3% for the vehicle.4 Therefore, tavaborole does not appear to offer any clinical advantage over existing therapy. The cost was not available at the time of this review.
REFERENCES
- Kerydin Prescribing Information. Anacor Pharmaceuticals, Inc.; Palo Alto, CA; July 2014.
- Gupta AK, et al. Molecular determination of mixed infections of dermatophytes and nondermatophyte molds in individuals with onychomycosis. J Am Podiatr Med Assoc 2014;104:330-336.
- Ciclopirox Prescribing Information. Princeton, NJ: Sandoz; July 2014.
- Jublia Prescribing Information. Valeant Pharmaceuticals: Bridgewater, NJ; June 2014.
