For BPH (benign prostatic hyperplasia), both dutasteride 0.5 mg and finasteride 5 mg are FDA-approved treatments. The one large head-to-head trial, EPICS, ran for 12 months in 1,630 men and concluded that the two were similarly effective: prostate volume fell with both drugs with no significant difference between them, and symptom scores and peak urinary flow improved to a similar degree. The choice usually comes down to cost, prescriber preference, and individual patient factors.
FDA-Approved Doses for BPH
The BPH doses are different from those used for hair loss:
- Dutasteride: 0.5 mg once daily (Avodart, generic)
- Finasteride: 5 mg once daily (Proscar, generic). This is five times the finasteride hair-loss dose of 1 mg (Propecia)
Head-to-Head Efficacy: The EPICS Trial
The EPICS (Enlarged Prostate International Comparator Study) trial was a multicenter, randomized, double-blind, 12-month, parallel-group study directly comparing dutasteride 0.5 mg/day (n = 813) with finasteride 5 mg/day (n = 817) in 1,630 men aged 50 or over with a clinical diagnosis of BPH. After a 4-week placebo run-in, patients received 48 weeks of blinded treatment, followed by an optional 24-month open-label phase on dutasteride. The primary endpoint was change in prostate volume. Key findings:
- Prostate volume (primary endpoint): both dutasteride and finasteride were effective at reducing prostate volume, with no significant difference between the two treatments during the study
- Symptom score: similar reductions in mean American Urological Association Symptom Index (AUA-SI) scores in both groups
- Peak urinary flow: similar improvements in maximum urinary flow rate (Qmax) in both groups
- Adverse events: a similar percentage of adverse events in each treatment group, with no new adverse events reported during the open-label phase
COMBAT Trial: Adding Tamsulosin
The CombAT (Combination of Avodart and Tamsulosin) trial compared dutasteride alone, tamsulosin alone, and the combination in 4,844 men with BPH over 4 years. It had no placebo arm, which its authors list as a study limitation, so it produces no dutasteride-versus-placebo figures. Key findings relevant to the dutasteride vs finasteride question:
- Combination therapy gave significantly greater symptom benefit than either monotherapy at 4 years, and was significantly superior to both monotherapies at reducing the relative risk of BPH clinical progression
- For acute urinary retention or BPH-related surgery, combination therapy was superior to tamsulosin alone but not to dutasteride alone
- The dutasteride-versus-placebo numbers come from a different set of studies. In the three pooled 2-year placebo-controlled trials in the FDA label, dutasteride cut the incidence of acute urinary retention from 4.2% on placebo to 1.8%, a 57% reduction in risk, and BPH-related surgery from 4.1% to 2.2%, a 48% reduction in risk
Full Comparison Table
| Parameter | Dutasteride 0.5 mg | Finasteride 5 mg |
|---|---|---|
| FDA approval (BPH) | Yes (2001) | Yes (1992) |
| 5AR isoforms blocked | Type 1 + Type 2 | Type 2 only |
| Serum DHT reduction | ~94% at 1 year on 0.5 mg/day (FDA label) | ~70% on 5 mg/day (Proscar label) |
| Prostate volume reduction (12 mo, EPICS) | Both effective, with no significant difference between the two treatments | |
| IPSS improvement | Similar | Similar |
| PSA reduction | ~50% within 3 to 6 months (FDA label) | ~50% within 6 months (Proscar label) |
| Risk of AUR vs placebo (separate trials, not head to head) | 57% reduction over 2 years (FDA label) | 57% reduction in PLESS (Proscar label) |
| Sexual side effects | Similar | Similar |
| Terminal half-life | ~5 weeks (FDA label) | ~6 hours, ~8 hours in men over 70 (Proscar label) |
| Combination product available | Yes (Jalyn with tamsulosin in the US; Duodart or Combodart elsewhere) | No FDA-approved fixed-dose combination |
Which Is Better for BPH?
For most patients, either drug is an appropriate choice. EPICS found no significant difference between them in prostate volume reduction, symptom score or peak urinary flow at 12 months. Dutasteride does have a fixed-dose combination product with tamsulosin (Jalyn in the United States, Duodart or Combodart elsewhere), which simplifies dosing for patients who need combination therapy. Finasteride has a longer track record, is generally less expensive, and is preferred by some urologists based on familiarity.
For men who also have androgenetic alopecia, dutasteride may be the preferred choice because one prescription can address both conditions. Note that dutasteride is not FDA-approved for hair loss, so that use is off-label, and that the BPH dose (0.5 mg) is the same as the dose used off-label for hair loss, so there is no dosing conflict.
Dutasteride vs finasteride for hair loss · Dutasteride for BPH · Dutasteride + Tamsulosin (Duodart)
Sources
- Nickel JC, et al. Comparison of dutasteride and finasteride for treating benign prostatic hyperplasia: the Enlarged Prostate International Comparator Study (EPICS). BJU Int. 2011;108(3):388-94. PubMed
- Roehrborn CG, 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. PubMed
- FDA. Avodart (dutasteride) prescribing information. accessdata.fda.gov
- FDA. Proscar (finasteride) prescribing information. DailyMed
- Tacklind J, et al. Finasteride for BPH. Cochrane Database Syst Rev. 2010;10:CD006015. PubMed