Effect of Testosterone Supplementation With and Without a Dual 5[alpha]-Reductase Inhibitor on Fat-Free Mass in Men With Suppressed Testosterone Production: A Randomized Controlled Trial

• Published in: JAMA : the journal of the American Medical Association Vol. 307; no. 9; p. 931
• Main Authors: Bhasin, Shalender, Travison, Thomas G, Storer, Thomas W, Lakshman, Kishore, Kaushik, Manas, Mazer, Norman A, Ngyuen, Ahn-Hoa, Davda, Maithili N, Jara, Hernan, Aakil, Adam, Anderson, Stephan, Knapp, Philip E, Hanka, Samson, Mohammed, Nurahmed, Daou, Pierre, Miciek, Renee, Ulloor, Jagadish, Zhang, Anqi, Brooks, Brad, Orwoll, Katie, Hede-Brierley, Leife, Eder, Richard, Elmi, Ayan, Bhasin, Geeta, Collins, Lauren, Singh, Ravinder, Basaria, Shehzad
• Format: Journal Article
• Language: English
• Published: Chicago American Medical Association 07-03-2012
• Subjects: Clinical trials; Drug therapy; Inhibitor drugs; Men; Muscular system; Testosterone
• ISSN: 0098-7484; 1538-3598

Bhasin et al determine whether testosterone's effects on muscle mass, strength, sexual function, hematocrit level, prostate volume, sebum production, and lipid levels are attenuated when its conversion to 5α-dihydrotestosterone (DHT) is blocked by dutasteride, an inhibitor of 5α-reductase type 1 and 2. A total of 139 men were randomized; 102 completed the 20-week intervention. Men assigned to dutasteride were similar at baseline to those assigned to placebo. The mean fat-free mass gained by the dutasteride groups was 0.6 kg when receiving 50 mg/wk of testosterone enanthate, 2.6 kg for 125 mg/wk, 5.8 kg for 300 mg/wk, and 7.1 kg for 600 mg/wk. The mean fat-free mass gained by the placebo groups was 0.8 kg when receiving 50 mg/wk of testosterone enanthate, 3.5 kg for 125 mg/wk, 5.7 kg for 300 mg/wk, and 8.1 kg for 600 mg/wk. The dose-adjusted differences between the dutasteride and placebo groups for fat-free mass weren't significant. Changes in fat mass, muscle strength, sexual function, prostate volume, sebum production, and hematocrit and lipid levels didn't differ between groups. Changes in fat-free mass in response to graded testosterone doses didn't differ in men in whom DHT was suppressed by dutasteride from those treated with placebo, indicating that conversion of testosterone to DHT isn't essential for mediating its anabolic effects on muscle.