regimen and frequency. The delivery of topical pharmacologic drug to any dermatologic disease state is a heavily studied and debated subject; pharmacokinetic and -dynamic properties, solubility, concentration, potency, drug-drug interactions, absorption, and degradation are dependent on the exact formulation of the vehicle. For the treatment of AGA, the variable efficacy of topical FNS formulations likely depends on the composition of the vehicle.19 Currently, topical formulations of FNS have been tested as gels and solutions at varying concentrations, all of which have resulted in improved hair growth.10-16 There is no study comparing vehicle delivery (gel versus solution), and it is unknown which formulation is the most effective at penetrating the scalp, stabilizing FNS over a period of time (ie, prolonging shelf-life), delivering drug, and producing hair regrowth. Combining topical FNS with MNX and/or dutasteride has shown greater efficacy at hair regrowth than topical MNX alone,14 and also allowed for the maintenance of hair density. Researchers have optimized the penetration of FNS into the dermis by modulating the type and size of particles transporting the medication across the skin. Studies evaluating the efficacy of nanoparticle delivery have shown enhanced absorption of FNS with smaller particles, particularly in the liquid crystalline variation.20,21 Liposomes and microplated films are also successful delivery methods, as well as the use of absorption enhancers, such as ethanol and propylene glycol.22,23,24 A head-to-head comparison of compounds used to deliver nanoparticles has yet to be done, and no conclusions can be drawn at this time regarding which formulation will be most efficacious, with the least amount of adverse events, and the most cost-effective. Although most studies apply topical solution twice daily, once daily application of topical FNS is more effective at decreasing scalp DHT levels.13 Other studies reveal that combination of topical medications such as MNX 5% with FNS 0.1% may have synergistic and additive effects compared to single agent usage.14,15,16In the future, further research clarifying an optimal drug-delivery system, ideal concentration and frequency of the drug application, the adverse effect profile, as well as use in other hair loss disorders is required to determine the full extent to which topical FNS may be used.
AGA is a debilitating chronic condition, causing a great deal of psychological patient morbidity and decreased patient quality of life. Preliminary results regarding the application of topical FNS for the treatment of AGA are promising. Current data suggests that there may be a therapeutic potential for topical FNS in the treatment of AGA, while minimizing unwanted systemic side effects associated with oral use. Topical FNS appears to be non-inferior for hair regrowth when compared to systemic FNS. Combination therapies including topical FNS, as well as MNX or dutasteride, may be more effective than topical FNS alone. Topical FNS is not widely used despite its proven efficacy and lack of side effects, most likely due to the lack of evidence-based research. At this time it is unknown whether the cost of compounding topical FNS is a barrier to treatment. Given the benefits of topical FNS in both male and female AGA patients, further studies are warranted to determine the efficacy of long-term hair regrowth, therapeutic safety, cost-effectiveness, patient tolerability, and satisfaction.
The authors have no conflicts of interest to disclose and have received no financial support for this research.
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Natasha Atanaskova Mesinkovska MD PhD firstname.lastname@example.org