Evaluation of androgens in the scalp hair and plasma of patients with male-pattern baldness before and after finasteride administration

Summary Background Finasteride, a competitive inhibitor of the enzyme 5α‐reductase II, is widely used as a medical treatment for patients with male‐pattern baldness (MPB), which is affected by the distribution of androgenic steroids. It is also notable that the androgenic effect in MPB is different for each region of the head. Objectives To study the effect of the drug finasteride, we quantified androgenic steroids in the vertex and occipital scalp hair and in the plasma of patients with MPB. Methods The patients with MPB, aged 23–52 years, were treated with finasteride 1 mg daily for 5 months. The hair and plasma samples were hydrolysed, extracted with n‐pentane, and derivatized with MSTFA : NH4I : DTE (1000 : 4 : 5, v/w/w). We analysed the concentrations of dihydrotestosterone (DHT) and testosterone (T) in the hair and plasma using gas chromatography–mass spectrometry (GC‐MS). Results In the hair, the ratio of DHT/T was decreased in the vertex scalp hair after the individual received finasteride (P