Dutasteride
/ Dual 5-alpha-reductase inhibitor (type 1 and type 2; small molecule)ALIAS · Avodart (trade) · Jalyn (trade — combination) · Dutasteride
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Tier 1. FDA-approved 2001 (Avodart) for symptomatic benign prostatic hyperplasia and 2010 (Jalyn) as a fixed-dose combination with tamsulosin. Off-label use for androgenetic alopecia is supported by smaller randomised trials (Olsen 2006) but is not an FDA-approved indication. Multiple Phase 3 RCTs in BPH including the four-year CombAT study (Roehrborn 2010).
Dutasteride is a synthetic 4-azasteroid that irreversibly inhibits both isoenzymes of 5-alpha-reductase (type 1 and type 2), reducing the conversion of testosterone to dihydrotestosterone (DHT). Suppression of circulating DHT is more profound and complete than with selective type 2 inhibitors such as finasteride: published comparator studies report serum DHT reduction of approximately 90 percent or more with dutasteride versus approximately 70 percent with finasteride at standard doses. The effect on prostate volume in BPH and on miniaturisation of scalp hair follicles in androgenetic alopecia derives from reduced local DHT exposure.
Tier 1. The CombAT study (Roehrborn 2010) randomised approximately 4,800 men with moderate-to-severe BPH to dutasteride, tamsulosin, or the combination over four years and reported the combination was superior to either monotherapy on symptom score and disease progression endpoints. Smaller randomised trials in androgenetic alopecia (Olsen 2006) reported greater hair count gains with dutasteride than with finasteride or placebo at 24 weeks; the AGA indication is off-label in the United States although approved in Korea and a few other jurisdictions.
Class adverse events include decreased libido, erectile dysfunction, ejaculatory disorders, and gynecomastia, with frequencies similar to or modestly higher than finasteride in head-to-head data. Persistent post-finasteride syndrome reports apply by class extension to dutasteride although a causal relationship remains debated. Dutasteride distorts serum prostate-specific antigen interpretation and produces feminisation of male foetuses with maternal exposure, so women of childbearing potential should not handle leaking capsules.
Regulatory status
- FDA status:
- FDA-approved
- Compounding:
- Not eligible for compounding (approved, not in shortage)
The off-label androgenetic alopecia use case has a smaller randomised-trial base than the BPH indication, and head-to-head dutasteride versus finasteride data in AGA come from relatively short trials with surrogate endpoints. The longer half-life of dutasteride (approximately five weeks at steady state) means washout after discontinuation is prolonged, a consideration not present with finasteride. Vendor compounded preparations (oral, topical) for AGA are not FDA-approved formulations and the clinical-trial data do not transfer cleanly to compounded dosage forms.