A Study of Tadalafil (LY450190) in Participants With Lower Urinary Tract Symptoms (LUTS) Suggestive of Benign Prostatic Hyperplasia LUTS (BPH-LUTS).

Inclusion criteria

• Present with benign prostatic hyperplasia (BPH; also referred to as BPH-LUTS), based on the disease diagnostic criteria, at study entry.
• Have been treated with a stable dose of an alpha1 blocker (tamsulosin 0.2 mg once daily or silodosin 4 mg twice daily) for at least 8 weeks prior to screening, and continue the same alpha1 blocker at the same dose for the entire duration of the study.
• Are Japanese men.
• Have prostate volume ≥20 milliliters (mL) estimated by transabdominal or transrectal ultrasound at screening.
• Have BPH-LUTS with a Total International Prostate Symptom Score (IPSS) of ≥12 at screening and baseline.
• Have moderate LUTS with urinary peak flow rate (Qmax) ≥4 to ≤15 mL/second at baseline, while meeting both of the following criteria:

• Prevoid total bladder volume ≥150 to ≤550 mL as assessed by ultrasound
• Minimum voided volume ≥125 mL
• Demonstrate ≥80% compliance with alpha1 blocker treatment* during the screening period, documented at baseline

• *Tamsulosin: (Number of doses taken / Number of days to be treated) × 100
• Silodosin: (Number of doses taken / Number of days to be treated) × 50

Exclusion criteria

• Prostate-specific antigen (PSA) >10.0 nanograms (ng)/mL at screening.
• PSA ≥4.0 to ≤10.0 ng/mL at screening if prostate malignancy has not been ruled out to the satisfaction of a urologist.
• Bladder post-void residual (PVR) ≥150 mL by ultrasound determination at screening.
• History of any of the following pelvic conditions:

• Pelvic surgery or any other pelvic procedure, including radical prostatectomy, pelvic surgery for removal of malignancy, or bowel resection
• Pelvic radiotherapy
• Any pelvic surgical procedure on the urinary tract, including minimally invasive BPH-LUTS therapies and penile implant surgery
• Lower urinary tract malignancy or trauma
• Lower urinary tract instrumentation (including prostate biopsy) within 30 days of screening.
• History of urinary retention or lower urinary tract (bladder) stones within 6 months of screening.
• History of urethral obstruction due to stricture, valves, sclerosis, or tumor at screening.
• History of any of the following treatments within the indicated duration:

• Antiandrogens within 11 months before screening
• Dutasteride within 5 months before screening
• Finasteride within 2 months before screening
• Any erectile dysfunction treatment previously or currently
• Any overactive bladder treatment within 4 weeks before screening
• Have a diagnosis or history of prostate cancer at screening.
• Current or history of malignancy at screening (except for treatment-free and relapse-free for ≥3 years at screening).
• Clinical evidence or history of any of the following bladder conditions:

• Underactive Bladder
• Detrusor-sphincter dyssynergia (contraction of the detrusor without sphincter relaxation)
• Interstitial cystitis
• Clinical evidence of any of the following urinary tract conditions:

• Active urogenital infection
• Clinically significant microscopic hematuria as determined by a urologist
• History of significant renal insufficiency meeting either of the following:

• Receiving renal dialysis
• Creatinine clearance (CLcr) <30 mL/minute
• Clinical evidence of severe hepatic impairment or Aspartate Transaminase (AST) or Alanine Transaminase (ALT) >3 times the upper limit of normal range.
• History of any of the following cardiac conditions:

• Current or history of angina requiring treatment with nitrates or nitric oxide donors
• Current or history of unstable angina
• Positive cardiac stress test without documented evidence of subsequent, effective cardiac intervention (e.g., coronary angioplasty)
• History of any of the following coronary conditions within 90 days of screening:

• Myocardial infarction
• Coronary artery bypass graft surgery
• Percutaneous coronary intervention (for example, angioplasty or stent placement)
• Any evidence or history of heart failure (New York Heart Association [NYHA] ≥ Class III).
• Currently receiving alpha1 blocker therapy for the treatment of hypertension.
• Current or history of any of the following symptoms:

• Symptoms associated with orthostasis (e.g., recurrent episodes of dizziness, lightheadedness, loss of consciousness, syncope)
• Causeless fall within 1 year of screening
• Blood pressure-related findings of any of the following at screening:

• Systolic blood pressure >160 or <90 millimeters of mercury (mm Hg)
• Diastolic blood pressure >100 or <50 mm Hg
• Malignant hypertension
• Uncontrolled arrhythmia