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Avodart Muscle Preservation Strategies: What the Evidence Actually Shows

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At a glance

  • Drug / dutasteride 0.5 mg oral capsule (Avodart) [1]
  • Approved use / symptomatic BPH; not approved for hair loss or prostate cancer prevention [1]
  • DHT effect / median serum DHT down 85% at 1 week and 90% at 2 weeks [1]
  • Testosterone effect / median rose 19% to 26%, within the physiologic range [1]
  • PSA effect / about 50% lower within 3 to 6 months; the label says an isolated on-treatment value after 3 months is doubled for comparison [1]

What Dutasteride Does to Androgens

Dutasteride is a competitive, specific inhibitor of both type 1 and type 2 5-alpha-reductase and does not bind the androgen receptor [1]. It is approved only for symptomatic BPH, alone or with tamsulosin; hair-loss use is off-label [1].

Median serum DHT fell 85% after 1 week and 90% after 2 weeks on 0.5 mg daily, and 94% at 1 year [1]. Median serum testosterone rose about 19% to 26% but stayed inside the physiologic range [1]. The terminal half-life at steady state is about 5 weeks, and levels stay above 0.1 ng/mL for up to 4 to 6 months after the last dose [1].

What the Large Trials Measured

CombAT randomized 4,844 men aged 50 or older with BPH to dutasteride 0.5 mg, tamsulosin 0.4 mg or both for 4 years; the primary endpoint was time to acute urinary retention or BPH-related surgery [4]. REDUCE compared dutasteride with placebo for 4 years in men aged 50 to 75 with a prior negative biopsy and a PSA of 2.5 to 10 ng/mL; its question was biopsy-detected prostate cancer, which was found in 659 of 3,305 men on dutasteride versus 858 of 3,424 on placebo [5].

Practical Muscle-Preservation Guidance

The American College of Sports Medicine position stand recommends progressive resistance training 2 to 3 days a week for novices and 4 to 5 days a week for advanced trainees, periodized from 1 to 12 repetitions with emphasis on the 6 to 12 repetition zone for hypertrophy [2]. A 2018 review describes muscle protein synthesis rising dose-responsively with amino acid availability, with leucine the primary agonist and resistance exercise amplifying that rise [3].

Frequently asked questions

Does dutasteride cause muscle loss?
No dutasteride trial we found measured those outcomes. Median serum DHT fell 90% by 2 weeks on 0.5 mg daily, while median testosterone rose about 19% to 26% and stayed within the physiologic range [1].
Does dutasteride lower testosterone?
No. Median serum testosterone rose about 19% to 26% and remained within the physiologic range in the label data [1].
What training and protein intake are supported?
The ACSM position stand recommends progressive resistance training 2 to 3 days a week for novices and 4 to 5 days a week for advanced trainees, periodized from 1 to 12 repetitions [2]. A 2018 review describes protein feeding raising muscle protein synthesis dose-responsively, with leucine the main agonist [3].
Is dutasteride approved for hair loss?
No. Avodart is approved for symptomatic benign prostatic hyperplasia in men with an enlarged prostate, including in combination with tamsulosin; hair-loss use is off-label [1].

References

  1. U.S. National Library of Medicine, DailyMed. Avodart (dutasteride) soft gelatin capsules, Waylis Therapeutics prescribing information. Avodart (dutasteride) soft gelatin capsules, Waylis Therapeutics label
  2. American College of Sports Medicine. American College of Sports Medicine position stand. Progression models in resistance training for healthy adults. Med Sci Sports Exerc. 2009;41(3):687-708. American College of Sports Medicine position stand. Progression models in resistance training for healthy adults
  3. Stokes T, Hector AJ, Morton RW, McGlory C, Phillips SM. Recent Perspectives Regarding the Role of Dietary Protein for the Promotion of Muscle Hypertrophy with Resistance Exercise Training. Nutrients. 2018;10(2). Recent Perspectives Regarding the Role of Dietary Protein for the Promotion of Muscle Hypertrophy with Resistance Exercise Training
  4. Roehrborn CG, Siami P, Barkin J, Damião R, Major-Walker K, Nandy I, et al. The effects of combination therapy with dutasteride and tamsulosin on clinical outcomes in men with symptomatic benign prostatic hyperplasia: 4-year results from the CombAT study. Eur Urol. 2010;57(1):123-31. The effects of combination therapy with dutasteride and tamsulosin on clinical outcomes in men with symptomatic benign prostatic hyperplasia: 4-year results from the CombAT study
  5. Andriole GL, Bostwick DG, Brawley OW, Gomella LG, Marberger M, Montorsi F, et al. Effect of dutasteride on the risk of prostate cancer. N Engl J Med. 2010;362(13):1192-202. Effect of dutasteride on the risk of prostate cancer
Evidence overview for dutasteride: Avodart Muscle Preservation Strategies: What the Evidence Actually Shows