Muscle power caused by exogenous testosterone is not affected by usage of dutasteride

According to a trial, the 5-alpha reductase inhibitor dutasteride (Avodart) doesn’t influence negatively on muscle mass in healthy men who take testosterone.
A research related to this issue was conducted. While fat-free mass was enhanced by 0,6-7,1 kg during 20 weeks in men who administered 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 men of these 2 groups.
5-alpha reductase inhibitors are used clinically to cure benign prostatic hyperplasia (BPH) and androgenic alopecia. These are dysfunctions that usually affect middle-aged and elderly males.
DHT represents the chief metabolite of testosterone. But the function of DHT in human development is not studied well. It is supposed that DHT plays vital role in development of prostate and phallus.
Middle-aged and old males with low testosterone levels who administer testosterone medications have risks related to low muscle mass and sexual troubles.
Specialists also put efforts to develop nonsteroidal selective androgen receptor modulators (SARMs). It is confirmed that SARMs and 5-alpha reductase inhibitors are safe because DHT is probably not necessary for effects on muscle mass, strength and sexual life. It is also doubted whether DHT has any role for androgen’s effects on hematocrit, hemoglobin, lipids and certain other factors.
Shalender Bhasin and his colleagues at the Boston University have conducted a clinical trial in order to see whether 5?-reduction to DHT is needed in order to mediate androgen’s effects on fat-free mass. Moreover, the experts evaluated role of 5?-reduction on sexual functions, hematocrit and levels of lipid.
The research conducted by Bhasin and his colleagues implicated healthy men who were 18- 50 years old and had normal levels of testosterone. They used Testosterone Enanthate and dutasteride or placebo. Dosages of Testosterone Enanthate ranged from 50 to 600 mg weekly.
Since 5 ?-reductase inhibitors increase testosterone levels, all men were given also gonadotropin-releasing hormone agonist in order to block natural testosterone.
The results of the research manifested that fat-free mass was increased due to administration of testosterone. It didn’t differ essentially in men of these two groups. Muscle power which was also increased due to testosterone use didn’t differ between the two groups as well. Sexual activity, volume of prostate, sebum production, hemoglobin, acne, hematocrit didn’t differ substantially between those who took placebo and dutasteride.
The specialists note that effectiveness of 5?-reductase inhibitors may be limited in men who have normal or enhanced testosterone levels. 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 manifested that muscle mass is not affected by 5?-reductase inhibitors.  Males have to know that if they have high levels of testosterone or introduce exogenous testosterone in their bodies, 5?-reductase inhibitors will not cause shrinkage of prostate.