New study: dutasteride doesn’t affect fat-free muscle mass in men that use testosterone

According to a trial, the 5-alpha reductase inhibitor dutasteride (Avodart) doesn’t affect fat-free mass in healthy males who take testosterone.
A study linked with this issue was conducted. While fat-free mass was enhanced by 0,6-7,1 kg during 20 weeks in men who applied dutasteride and Testosterone Enanthate, fat-free mass was enhanced by 0,8-8,1 kg in those who were given placebo and testosterone. As for muscle strength, sexual functions and volume of prostate, they didn’t differ in men of these 2 groups.
5-alpha reductase inhibitors are used clinically for treatment of benign prostatic hyperplasia (BPH) and androgenic alopecia. These are dysfunctions which usually occur in middle-aged and old men.
DHT represents the main metabolite of testosterone. But the role of this metabolite in human development is not clearly understood. It is suggested that DHT has vital role in development of prostate and phallus.
Middle-aged and elder men with low testosterone levels that apply testosterone medications have risks connected with reduced muscle size and sexual problems.
Nonsteroidal selective androgen receptor modulators (SARMs) are also currently studied and developed. It is confirmed that SARMs and 5-alpha reductase inhibitors are safe because DHT is probably not necessary for effects on muscle mass, muscle power and sexual activity. It is also doubted whether DHT plays 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 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 study conducted by Bhasin and his colleagues implicated healthy males that were 18- 50 years old and had normal levels of testosterone. They applied Testosterone Enanthate and dutasteride or placebo. Measures of Testosterone Enanthate ranged from 50 to 600 mg per week.
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 study showed that fat-free mass was increased due to intake of testosterone. It didn’t differ essentially in males of these 2 groups. Muscle power that was also enhanced due to application of testosterone didn’t differ between the two groups as well. Sexual activity, prostate volume, sebum production, hemoglobin, acne, hematocrit didn’t differ essentially between those who used placebo and dutasteride.
The specialists conclude that effectiveness of 5?-reductase inhibitors may be limited in men that have normal or enhanced levels of testosterone. That’s why it is important to check testosterone levels in order to set how bodies will respond to 5 ?-reductase inhibitors.
So, the study has displayed that muscle mass is not affected by 5?-reductase inhibitors.  Males should know that if they have enhanced levels of testosterone or introduce exogenous testosterone in their bodies, 5?-reductase inhibitors will not cause shrinkage of prostate.