Androgenetic alopecia may affect self-esteem and quality of life in several affected individuals. There are two FDA-approved drugs for pattern baldness: topical minoxidil and finasteride, both of which require at least a 4- to 6-month trial before noticing improvement and must be used indefinitely to maintain a response. As such, medication adherence often can be poor. Furthermore, initiation of the drug may cause an initial shedding phase.~Minoxidil was the first and, so far, the only topical product that has been FDA approved for the treatment of AGA. Minoxidil was originally developed as an oral medication for hypertension. Hypertrichosis was found in 24-100 % of patients treated with oral minoxidil, which led to the treatment of AGA with topical minoxidil.~Androgenic Alopecia is caused by the overproduction of 5αdihydrotestosterone (5α-DHT), a potent androgen within the hair follicle, specifically the dermal papilla (DP) cells that are the main regulators of hair growth and are the only site of 5α-DHT action.~Sildenafil is a selective inhibitor of phosphodiesterase 5 and was originally developed as an anti-anginal drug due to its vasodilatory and antiplatelet coagulation properties. Sildenafil enhances the proliferation of human dermal papilla cells and up-regulates the mRNA expression of vascular endothelial growth factor and platelet-derived growth factor (PDGF) which are responsible for hair growth.~Topical sildenafil 1% has been used in the treatment of male androgenic alopecia.
Androgenetic alopecia (AGA) is hair loss with specific clinical pattern, It Is characterized by follicular miniaturization, which occurs due to systemic androgens and genetic factors. Prevalence differs according to ethnic groups. It is more common and more severe in white men than in Asian and black men. The incidence increases with age. According to Hamilton's study, the prevalence is 30% in men at the age of 30, and 50% in the age of 50. Generally, the age of onset is the 3rd and 4th decade.