5-alpha reductase inhibitors don’t hinder anabolic effects caused by exogenous testosterone

According to a trial, treatment with dutasteride (Avodart), a 5-alpha reductase inhibitor, doesn’t affect fat-free mass in healthy males that take testosterone.
A research linked with this issue was conducted. While fat-free mass was increased by 0,6-7,1 kg during 20 weeks in men who took dutasteride and Testosterone Enanthate, fat-free mass was enhanced by 0,8-8,1 kg in those that administered placebo and testosterone. As for muscle strength, sexual functions and volume of prostate, they didn’t differ in men of these two groups.
5-alpha reductase inhibitors are used clinically to cure benign prostatic hyperplasia (BPH) and androgenic alopecia. These are dysfunctions which commonly trouble middle-aged and elderly males.
DHT represents the main metabolite of testosterone. But the function of this metabolite in human development is not studied well. It is suggested that DHT plays vital role in development of prostate and phallus.
Middle-aged and elder males with low testosterone levels that take testosterone medications have risks related to decreased muscle size and sexual disorders.
Scientists also study and develop nonsteroidal selective androgen receptor modulators (SARMs). It is claimed that SARMs and 5-alpha reductase inhibitors are safe because DHT is supposedly not necessary for effects on fat-free mass, energy and sexual activity. It is also doubted whether DHT has any role for androgen’s effects on hematocrit, hemoglobin, lipids and some other factors.
Shalender Bhasin and his colleagues at the Boston University have conducted a clinical trial in order to define whether 5?-reduction to DHT is required in order to mediate androgen’s effects on muscle mass. Furthermore, the experts evaluated role of 5?-reduction on sexual functions, hematocrit and levels of lipid.
The study conducted by Bhasin and his colleagues involved healthy males who were 18- 50 years old and had normal testosterone levels. They administered Testosterone Enanthate and dutasteride or placebo. Doses of Testosterone Enanthate varied from 50 to 600 mg weekly.
Since 5 ?-reductase inhibitors enhance testosterone levels, all men were given also gonadotropin-releasing hormone agonist in order to block natural testosterone.
The results of the study showed that fat-free mass was enhanced due to usage of testosterone. It didn’t differ substantially in males of these 2 groups. Muscle strength which was also increased due to usage of testosterone didn’t differ between the two groups too. Sexual functions, volume of prostate, sebum production, hemoglobin, acne, hematocrit didn’t differ significantly between those who used placebo and dutasteride.
The specialists state that effectiveness of 5?-reductase inhibitors can be limited in males that have normal or high levels of testosterone. That’s why it is important to check levels of testosterone in order to determine how bodies will respond to 5 ?-reductase inhibitors.
So, the study has shown that muscle mass is not affected by 5?-reductase inhibitors.  Men should know that if they have increased levels of testosterone or introduce exogenous testosterone in their bodies, 5?-reductase inhibitors will not cause shrunken prostate.