Clinical trials

Jump to: FinasterideDutasteride

This page summarizes clinical trials of finasteride and dutasteride, focusing on phases II–IV. For details on study design and sponsorship, see papers and documents in the last column of tables. (For background, see an introduction from NIH: What are Clinical Trials and Studies?)

Finasteride was developed by Merck. Dutasteride was developed by GlaxoSmithKline (now GSK). The trials are organized around the following indications and events:

  • 1992: Finasteride (5 mg) approved for treatment of benign prostatic hyperplasia (BPH), with brand name Proscar
  • 1994–2004: Finasteride (5 mg) studied for the prevention of prostate cancer (PCPT trial)
  • 1997: Finasteride (1 mg) approved for treatment of male pattern hair loss (MPHL), with brand name Propecia
  • 2001: Dutasteride (0.5 mg) approved for treatment of BPH, with brand name Avodart
  • 2003–2010: Dutasteride studied for prevention and management of prostate cancer (REDUCE and REDEEM trials, respectively)

BPH and prostate cancer are treated by urologists, while MPHL is treated by dermatologists. Trials for each indication involved physician-researchers in the relevant specialty as investigators, authors and consultants. Results were often reported in that specialty’s journals.

Avodart (dutasteride 0.5 mg) has been approved for the treatment of male pattern hair loss (androgenetic alopecia) in South Korea and Japan. It is not approved for this indication in the United States, and no approval for treating hair loss has been found in countries regulated by the European Medicines Agency.

For more information about both drugs, see a comparison table, drug labels and a post on the origins of finasteride.

Abbreviations: AGA, androgenetic alopecia; BPH, benign prostatic hyperplasia; MPHL, male pattern hair loss.


In column 2, the number of patients refers to the number enrolled in the study, before randomization.

See also: Research of J. Imperato-McGinley whose work provided the basis for finasteride’s mechanism.

Condition treated / topicPurpose & participantsDatesPapers
BPHDetermine the hormonal effects of MK-906, an orally active 5a-reductase inhibitor, on serum androgens and androgen conjugates
12 Caucasian men, age 50–71; ~8 weeks
~1987–88Rittmaster 1989
Not specifiedEffect of finasteride on circulating androgens in men
Part 1: 42 men age 19–46; 11 days. Part 2: 30 men age 40–77; 14 days
~1988Gormley 1990
Stoner 1990 (review)
BPHEffects of a range of finasteride doses on androgen levels in men
69 male students, age not specified
~1988Vermeulen 1991
BPHFinasteride Study Group: Phase II trial
Effects of finasteride in patients with BPH
Study 1: 86 men age 40–80; 12 weeks + 12-week drug-free
Study 2: 104 men age 40–80; 24 weeks
~1988–89Stoner 1992
BPHCompare effect of finasteride on 1) 5ɑ-reduced C19 and C21 metabolites and 2) plasma T, DHT and LH in male pseudohermaphrodites and men aged 45–75 [note F1]
Group 1: ~41 men age 45–75. Group 2: 46 adult male pseudohermaphrodites with inherited 5ɑ-reductase deficiency
1980sImperato-McGinley 1990
BPHFinasteride Study Group: Phase II extension
Determine if previously reported short-term efficacy was maintained with longer-term therapy
67 men age 45–77; 1 year
~1989–90Gormley 1991
BPHFinasteride Study Group: North American Phase III trial
Safety and efficacy of finasteride in men with BPH
896 men age 40–83 with BPH; 12 months with 4-year open-label extension
~1990–91Gormley 1992
Guess 1993
Stoner 1994
Hudson 1999 (extension)
BPHFinasteride Study Group: International Phase III trial
Safety, tolerability and efficacy of finasteride 1 mg and 5 mg men with BPH
750 men age 40–80 with BPH; 12 months
~1990–91Finasteride Study Group 1993
Stoner 1994
BPHFinasteride Study Group
Long-term 6-year experience with finasteride for BPH, based on extensions of North American and International Phase III trials
~1990–1996Lowe 2003
BPHScandinavian Clinical Study of Finasteride in the Treatment of Benign Prostatic Hyperplasia
182 patients age 40–80 with urinary symptoms; 24 weeks with 12-month open extension
~1990–1991Beisland 1992
BPHLong-term urodynamic effects of finasteride in BPH: pilot study
UK. 69 men; 3 months with open extension
1992–93Kirby 1993
BPHCUSP: Community Based Study of Proscar
Efficacy, tolerability and effect on health-related quality of life in men with BPH
At community-based urology clinics; Black and Hispanic patients especially encouraged to participate
2342 men age 45 and older; 1 year
1990sByrnes 1995
BPHVeterans Affairs Cooperative Studies Benign Prostatic Hyperplasia Study Group
Efficacy and safety of finasteride, terazosin, or both in men with BPH
A community study conducted at Veterans Affairs outpatient clinics.
Men age 45–80; 1 year
1992–95Lepor 1996
Lepor 1998
BPHPROSPECT: Proscar Safety Plus Efficacy Canadian Two Year Study
Efficacy and safety of 2 years of treatment of moderate BPH
613 men age 45–80; 2 years
1992–94Nickel 1996
BPHPrimary Care Investigator Study Group
Efficacy and tolerability of finasteride in a primary care setting
2112 patients age 45 and older; 1 year
1993–95Tenover 1997
BPHEfficacy and safety of finasteride in men with BPH
50 men age 50–82; 6 months
~1994Yu 1995
Sexual functionEffect of finasteride (5 mg) on sleep-related erections, potency & libido
20 men (9 taking finasteride), age 41–64; 3 months
~1994Cunningham 1995
BPHFinasteride Long-Term Efficacy and Safety Study Group
Long-term effects of finasteride on symptoms of BPH and incidence of related outcomes including acute urinary retention and need for surgery
3040 men, mean age 64; 4 years
1990–92McConnell 1998
BPHPROWESS: Proscar Worldwide Efficacy and Safety Study
“A large study…to [clarify] issues of finasteride response and prostate size”
3270 men, age 50–75; 2 years
~1994–97Marberger 1998
BPHMTOPS: Medical Therapy of Prostatic Symptoms
Compare effects of doxazosin, finasteride, combination therapy and placebo on progression of BPH
3047 recruited, age 50 and older; mean follow-up 4.5 years
1993–98McConnell 1998
Kaplan 2016 (adverse experiences)
BPHEPICS: Enlarged Prostate International Comparator Study
Finasteride vs. dutasteride for BPH
Sponsored by GlaxoSmithKline
1630 men, age 50 and older; 1 year plus 2 year open-label phase
1998–2003Nickel 2011
Prostate cancer incidencePLESS: Proscar Long-term Efficacy and Safety Study
Prostate cancer incidence and predictive properties of PSA
3040 men, age 45–78; up to 4 years
1991–96Andriole 1998
Bruskewitz 1999
Roehrborn 1999
Yang 1999
Kaplan 2000
Roehrborn 2000
Wessells 2003
Roehrborn 2004
Prostate cancer preventionPCPT: Prostate Cancer Prevention Trial
Test whether finasteride could reduce the risk of prostate cancer (read more at National Cancer Institute – NIH)
Funded by National Cancer Institute. Run by Southwestern Oncology Group (SWOG)
18,882 men, age 55 and older; 10 years
1994–2004Coltman 1999 (update)
Higgins 2004 (current status)
Lotan 2005
Mellon 2005
Lucia 2007
Moinpour 2007
Advanced prostate cancer treatmentDetermine efficacy of the combination of finasteride and flutamide in select patients with advanced prostatic cancer
Run by urologists at University of Toronto
22 sexually active men with stages C and D1 carcinoma of the prostate, age 55–70; mean followup was 22 months
~1992–1994Fleshner 1993
Fleshner 1995
MPHLPhase 2 study 047: finasteride 5 mg for treatment of male pattern baldness
227 men, age 18–36; 1 year plus 2-year extension
1992–94Medical Review Part 1, from page 8 in New Drug Application to FDA
MPHLFinasteride Male Pattern Hair Loss Study Group
Phase 3 studies 087 (US) & 089 (International): Determine whether finasteride treatment leads to clinical improvement in men with male pattern hair loss (MPHL)
1553 men with MPHL, age 18–41; 1 year with four 1-year extensions
1994–96Medical Review in New Drug Application to FDA
Kaufman 1998
Finasteride Male Pattern Hair Loss Study Group 2002
Shapiro 2003
Price 2006
Kaufman 2008a
Kaufman 2008b
MPHLPhase 3 study 092: Efficacy and safety of finasteride in men with frontal hair loss
326 men, age 18–40 (mean age ~32.5); 1 year with 1-year open extension
~1994–96Leyden 1999
MPHLAdditional studies in Propecia New Drug Application
Study 081: Dose Range
Study 094: Safety
Study 065: Scalp DHT and Sebum
Study 031: Scalp DHT
Study 012: Semen Production #1
Study 056: Semen Production #2
1990sMedical Review Part 1, from p. 8
Roberts 1999 (Dose Range)
Drake 1999 (Scalp & Serum DHT)
(No publications found for: 094, Safety; 012: Semen Production #1; 056: Semen Production #2)
Semen parametersPotential effect and reversibility of effect of finasteride on semen parameters, prostate volume and serum PSA
181 men, age 19–41; 48 weeks with 60-week off-drug reversibility period
UnknownOverstreet 1999
MPHLEffect of finasteride on phases of hair growth cycle
10 centers in Europe; 2 centers in US
212 men, age 18–40; 48 weeks
Late 1990sVan Neste 2000
MPHLChanges in hair weight and hair count
66 men, age 22–40; 48 weeks with 48-week extension
UnknownPrice 2002
MPHLEfficacy of finasteride with placebo in the treatment of male pattern hair loss in nine pairs of male identical twins
9 pairs of identical twins; 1 year
UnknownStough 2002
MPHLFinasteride Male Pattern Hair Loss Study Group
Efficacy and tolerability in men aged 41 to 60 years with male pattern hair loss
424 men, age 41–60; 2 years
UnknownWhiting 2003
MPHLFinasteride in the treatment of Japanese men with male pattern hair loss
Sponsored by Banyu Pharmaceutical Co., Japan [note F2]
414 men, age 20–40; 48 weeks
2001–02Kawashima 2004
MPHLEvaluate whether finasteride improves scalp hair and growth in areas surrounding the transplant, and safety and tolerability in men undergoing hair transplant
79 men, age 20–45; 1 year
2000–03Leavitt 2005
Semen parameters & serum hormonesEffect of finasteride and dutasteride, relative to placebo, on semen parameters and serum levels of reproductive hormones
Sponsored by GlaxoSmithKline
99 men, age 18–55; 1 year, with follow-up for 24 weeks after end of treatment
1999–2001Amory 2007
MPHLThree related trials of finasteride in Japanese men with androgenetic alopecia. “The same patients were included in the three investigations, but each study period was completely different.” –Yanagisawa 2022
1. Efficacy and safety of finasteride 1 mg in 3177 Japanese men with androgenetic alopecia (2006–09)
2. Efficacy of finasteride in 801 Japanese Men with androgenetic alopecia (2000–08)
3. Long-Term (10-Year) efficacy of finasteride in 523 Japanese men with androgenetic alopecia (2005–09)
2000–09Sato 2011
Yoshitake 2015
Yanagisawa 2019
Yanagisawa 2022: summary of all trials
Acne in womenCompare efficacy, tolerability and safety of montelukast versus finasteride in the treatment of moderate acne in women.
65 female subjects with moderate acne vulgaris, age 15–38; 12 weeks.
2018–2020Rokni 2021
MPHL1. Efficacy and safety of topical finasteride compared to placebo
2. Degree of systemic exposure to finasteride
Sponsored by Polichem and Almirall
458 enrolled men, age 18–40; 24 weeks. Conducted at 45 sites in Europe.
2022Piraccini 2022

F1. C19 and C21 metabolites are “neuroactive and neuroprotective steroids, androgens and androgen precursors” (Stárka et al., 2006).
F2. Merck had a controlling stake in Banyu from the 1980s and took full ownership of the company in 2003.


In column 2, the number of patients refers to the number enrolled in the study, before randomization.

Condition treated / topicPurpose & participantsDatesPapers
BPHARIA3001 (US), ARIA3002 (US) & ARIA3003 (19 countries)
Dutasteride for BPH
4235 men, age 50 and older; 2 years
1997–2002Roehrborn 2002
Roehrborn 2004 (ARIA3001, 3002)
BPHARIA108898: Chinese Dutasteride Phase III Trial
Dutasteride in Chinese adults with BPH
253 men, age 50 and older; 6 months + 12-month extension
2007-2009Na 2012
BPHEPICS: Enlarged Prostate International Comparator Study
Finasteride vs. dutasteride for BPH
Non-US locations
1630 men, age 50 and older; 1 year plus 2 year open-label phase
1998–2003Nickel 2011
BPHCombAT: Combination of Avodart and Tamsulosin study
Effectiveness of dutasteride-tamsulosin combination therapy vs. dutasteride or tamsulosin in reducing risk of urinary retention, BPH-related surgery and BPH clinical progression
4844 men, age 50 and older with moderate-to-severe LUTS due to BPH; 4 years
2003–2009Roehrborn 2010
Montorsi 2011
See additional papers in note D1
BPHDutasteride in Japanese men with BPH
378 men, age 50 and older; 1 year with follow-up assessments for 16 weeks
2000sTsukamoto 2009
Prostate cancer preventionREDUCE: Reduction by Dutasteride of Prostate Cancer Events
Effect of dutasteride on the risk of prostate cancer
6729 men, age 60–75; 4 years
2003–2009Musquera 2008
Andriole 2010
Prostate cancer managementREDEEM: Reduction by Dutasteride of Clinical Progression Events in Expectant Management
Evaluate whether dutasteride decreases time to prostate cancer progression
302 men, age 48–82; 302 men recruited; 3 years
2007–2010Fleshner 2007
Fleshner 2012
MPHLARIA2004: Dutasteride versus finasteride for hair loss
by Dutasteride Alopecia Research Team
Phase II dose-ranging study
416 men, age 21–45; 24 weeks
2004Olsen 2006
Semen parameters & serum hormonesEffect of finasteride and dutasteride, relative to placebo, on semen parameters and serum levels of reproductive hormones
99 men, age 18–55; 1 year, with follow-up for 24 weeks after end of treatment
2000sAmory 2007
MPHLDutasteride in men with male pattern hair loss – Phase III
153 men, age 18–49; 6-month treatment with 4-month follow-up
2000sEun 2010
MPHLDifferent doses of dutasteride & finasteride in male subjects with androgenetic alopecia
917 men, age 20–50; 24 weeks
2010–2012Gubelin Harcha 2014
MPHLDutasteride for hair loss in identical twins
17 pairs of identical twins, age 18–50; 1 year
2000sStough 2007
MPHLSexual function in men taking dutasteride for AGA
117 men, age 23–50; 24 weeks + 24 weeks open-label extension
2014–2016Tsai 2018
BPHPARTEM: Prostatic artery embolisation versus medical treatment in patients with benign prostatic hyperplasia
Compare BPH symptoms after prostatic artery embolisation vs. combination therapy with dutasteride and tamsulosin hydrochloride.
2023Sapoval 2023
MPHLEfficacy and safety of dutasteride 0.5 mg in Korean men with AGA
99 men, age ≥18 years; treated for at least 5 years from October 2009 to December 2016
2024Choi 2024

D1. Additional papers related to CombAT trial: Roehrborn 2008, Barkin 2009, Becher 2009, Chung 2009, Haillot 2011, Roehrborn 2011a, Roehrborn 2011b, Roehrborn 2012, Oelke 2014, Roehrborn 2014