Patient description: The patient is a 63-year-old man presenting to the Emergency Department with a history of acute urinary retention in the past 2 days. Abdominopelvic CT scan revealed a large prostate and a bladder filled with urine. He is a candidate for urethral catheterization and TURP. Further evaluation revealed: Post-void residual: 71 mL Prostate volume (TRUS): 63 mL Prostate-specific antigen (PSA) level: 3.5 ng/mL His recent blood chemistry (3 days ago) was normal: Hgb: 13.6 g/dl WBC: 133000 /mm3 Plt: 370000 /ml PT: 12 second PTT: 34 second INR: 0.9 Creatinine: 0.5 mg/dl BUN: 10 mg/dl U/A: Color: yellow Appearance: cloudy PH: 5.3 Specific gravity: 1.010 Glc: 100 Nitrite: negative Ketone: none Leukocyte esterase: negative RBC: negative WBC: 2 WBCs/hpf U/C: negative

Clinical trial eligibility criteria: eligible ages (years): 50.0-999.0,  Prostatic Hyperplasia Male, age ≥ 50 years. Clinical diagnosis of benign prostate hypertrophy (BPH) . International Prostate Symptom Score (IPSS) ≥ 12 Prostate volume ≥30 ml (transrectal ultrasonography). Total serum prostate specific antigen (PSA) ≥1.5 ng/mL and ≤10 ng/mL. Free-to-total PSA ratio > 20% Maximum flow rate (Qmax) >5 mL/sec and ≤15 mL/sec and post-void residual volume of < 150 mL Willing and able to give written informed consent and comply with study procedures throughout study Able to swallow and retain oral medication Able to express personal thought and feeling Ability to read and comprehend information on the Sexual Function Inventory  History or evidence of prostate cancer (e.g. positive biopsy or ultrasound, suspicious digital rectal examination). Previous prostatic surgery (TURP, balloon dilatation, thermotherapy and stent replacement) or other invasive procedures to treat BPH. History of flexible/rigid cystoscopy or other instrumentation of the urethra within past 7 days History of acute urine retention (AUR) within past 3 months. Any causes other than BPH result in urinary symptoms or changes in flow rate (e.g. neurogenic bladder, bladder neck contracture, urethral stricture, bladder malignancy, acute or chronic prostatitis, acute or chronic urinary tract infections). History of breast cancer or clinical finding suggestive of malignancy. Use of any 5-alpha-reductase inhibitor (e.g. Proscar®, Propecia®), drugs with antiandrogenic properties (e.g. spironolactone, flutamide, bicalutamide, cimetidine, ketoconazole, progestational agents), drugs which induce gynecomastia or drugs which affect prostate volume, within past 6 months and throughout the study (other than as study medication). Do not use dutasteride within past 12 months. Do not use metronidazole for a long time. Concurrent use of anabolic steroids (eg. Durabolin®). Use of phytotherapy (eg: Tadenan®, Permixon®, etc) for BPH within 2 weeks of screening visit and/or predicted to need phytotherapy during the study. Use of any alpha-adrenoreceptor blockers (i.e. indoramin, prazosin, terazosin, tamsulosin, alfuzosin and doxazosin) within 2 weeks of screening visit and/or predicted to need any alpha blockers other than tamsulosin during the study. Use of any alpha-adrenoreceptor agonists (e.g. pseudoephedrine, phenylephrine, ephedrine) or anticholinergics (e.g. oxybutynin, propantheline) or cholinergics (e.g. bethanecol chloride) within 48 hours prior to all uroflowmetry assessments. Hypersensitivity to any alpha-/beta-adrenoreceptor blocker or 5-alpha-reductase inhibitor, or other chemically-related drugs. Concurrent use of drugs known or thought to have an interaction with tamsulosin and dutasteride. History of hepatic impairment or abnormal liver function tests at screening (defined ALT, AST, and/or alkaline phosphatase >2 times the upper limit of normal, or total bilirubin >1.5 times the upper limit of normal). History of renal insufficiency, or serum creatinine >1.5 times the upper limit of normal at screening. History of malignancies other than basal cell carcinoma or squamous cell carcinoma of the skin within the past 5 years. Subjects with a prior malignancy who have had no evidence of disease for at least 5 years prior to screening are eligible. Any unstable, serious co-existing medical condition(s) including, but not limited to, myocardial infarction, coronary bypass surgery, unstable angina, cardiac arrhythmias, clinically evident congestive heart failure, or cerebrovascular accident within past 6 months; medically uncontrollable diabetes or peptic ulcer disease History of postural hypotension, dizziness, vertigo or any signs and symptoms of orthostasis, which in judgments of investigator, could be exacerbated by tamsulosin History of unsuccessful treatment with tamsulosin or 'first dose' hypotensive episode on initiation of alpha-1-adrenoreceptor antagonist therapy. History of unsuccessful treatment with finasteride or dutasteride. Willing to have a child during the treatment period or within 6 months thereafter Having female partner who is a pregnant woman or in child-bearing age and refuse to use condom for sexual protection Willing to donate blood during treatment period or within 6 months thereafter. History or current evidence of drug or alcohol abuse within past 12 months. History of any illness might confound the results of the study or poses additional risk to the patient. Participation in investigational or marketed drug trial within 30 days preceding the screening visit and/or during the study treatment