Androgenic alopecia and dutasteride in hair mesotherapy: A short review

Androgenic alopecia (AGA) is the most common cause of patterned hair loss in predisposed men and women. AGA is a multifactorial and polygenetic condition, affecting up to 80% of men and 40-50% of women during life. AGA is characterized by a gradual reduction of the anagen and increase in telagen phase, leading to a progressive follicle miniaturization. As a consequence, terminal hairs are converted into vellus hairs decreasing hair density. The pathophysiology of AGA is heterogeneous and highly complex. A diverse combination of genetical factors, endocrine abnormalities, circulating androgens, drugs, diet and microinflammation in hair follicles of each individual are related to this condition. However, it is well known that androgens are the major modulators of male AGA but their specific action on female AGA is still under debate. Circulating testosterone is converted by 5a-reductase in 5a-dihydrotestosterone (DHT) in the periphery, a decrease of anagen phase occur, anticipating catagen phase in a complex process involving apoptosis as probably microinflammation. In AGA treatment, mesotherapy is being used with 5a-reductase inhibitors, especially dutasteride, injected directly on scalp. Thus, this updated review summarized the injectable use of dutasteride based on data available on PubMed until March 2017. Dutasteride, a second-generation inhibitor of 5a-reductase is more potent than finasteride due to the capability of inhibit types 1 and 2 of the enzyme. The efficacy and safety of hair mesotherapy with dutasteride were reported by distinct groups and the best results were achieved when this compound was used in combination with other substances, increasing hair growth. This result could be explained by the multifactorial pathophysiology of AGA, involving hair follicle sensitivity to DHT and microinflammation. Therefore, a multi-therapeutic approach seems to be more effective in AGA management. In conclusion, more studies are needed to establish protocols and to evaluate long- term dutasteride injections