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

According to a trial, the 5-alpha reductase inhibitor dutasteride (Avodart) doesn’t affect muscle mass in healthy men that take testosterone.
A research related to this issue was performed. While fat-free mass was increased by 0,6-7,1 kg during 20 weeks in males who applied dutasteride and Testosterone Enanthate, fat-free mass was increased by 0,8-8,1 kg in those that applied placebo and testosterone. As for muscle power, sexual functions and volume of prostate, they didn’t differ in males of these two groups.
5-alpha reductase inhibitors are utilized clinically to cure benign prostatic hyperplasia (BPH) and androgenic alopecia. These are disorders that usually appear in middle-aged and old males.
DHT represents the chief metabolite of testosterone. But the role of this metabolite in human development is not studied well. It is suggested that DHT has relevant role in development of prostate and phallus.
Middle-aged and elder males with low testosterone levels who use testosterone medications have risks connected with decreased muscle mass and sexual troubles.
Nonsteroidal selective androgen receptor modulators (SARMs) are also currently studied and developed. It is affirmed that SARMs and 5-alpha reductase inhibitors are safe because DHT is supposedly not necessary for effects on muscle mass, strength and sexual activity. It is also doubted whether DHT plays any role for androgen’s effects on hematocrit, hemoglobin, lipids and several 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 needed in order to mediate androgen’s effects on fat-free mass. Moreover, the scientist evaluated role of 5?-reduction on sexual activity, hematocrit and levels of lipid.
The study conducted by Bhasin and his colleagues implicated healthy men who were 18- 50 years old and had normal levels of testosterone. They took Testosterone Enanthate and dutasteride or placebo. Measures of Testosterone Enanthate varied from 50 to 600 mg weekly.
Since 5 ?-reductase inhibitors enhance levels of testosterone, all males were given also gonadotropin-releasing hormone agonist in order to block natural testosterone.
The results of the research showed that fat-free mass was increased due to administration of testosterone. It didn’t differ essentially in males of these two groups. Muscle power that was also enhanced due to intake of testosterone didn’t differ between the two groups too. Sexual functions, volume of prostate, sebum production, hemoglobin, acne, hematocrit didn’t differ substantially between those who used placebo and dutasteride.
The experts state that effectiveness of 5?-reductase inhibitors may be limited in men who have normal or enhanced levels of testosterone. That’s why it is necessary to check testosterone levels in order to determine how bodies will respond to 5 ?-reductase inhibitors.
So, the study has displayed that muscle mass is not affected by 5?-reductase inhibitors.  Men should know that if they have high levels of testosterone or introduce exogenous testosterone in their bodies, 5?-reductase inhibitors will not cause shrunken prostate.