Inclusion Criteria:

• Able to read, write and understand instructions related to study procedures and able to give written informed consent
• Able to swallow and retain oral medication
• Had a single, spontaneous episode of AUR related to BPH with a drained volume of between 500 and 1500ml
• Had a successful TWOC (defined as successful if the patient returns to satisfactory voiding within the first 24 hours after catheter removal without re-catheterisation) following 2 - 3 days treatment with alpha blocker (preferably alfuzosin 10mg OD) pre TWOC followed by up to seven days treatment with alpha blocker (preferably alfuzosin 10mg OD) post TWOC.
• Able to be randomised within 7 days of successful TWOC

Exclusion Criteria:

• Prostate volume (PV) of less than 30cc and greater than 80cc measured via Trans Rectal Ultrasound (TRUS) either at time of hospitalisation or as part of the screening / randomisation visit
• Previous episode of AUR prior to the current episode
• AUR not related to BPH i.e. postoperative retention following major abdominal / pelvis surgery
• Previous prostate or urethral surgery
• Previous positive prostate biopsy
• Any cause other than BPH that may result in urinary symptoms or changes in flow rates.
• Any unstable co-existing medical condition
• Previous 5-ARI use
• Previous alpha blocker treatment other than the study mandated 2 - 3 days pre and up to 7 days post TWOC period with alpha blocker (preferably alfuzosin 10mg OD)
• Use of prohibited meds (e.g. 5ARI's, anabolic steroids including testosterone, drugs with antiandrogenic properties)
• Liver enzymes (ALT, AST, ALP) at time of hospitalisation / screening visit greater than 2 x ULN or bilirubin at time of hospitalisation / screening visit greater than 1.5 x ULN.
• Serum creatinine at time of hospitalisation / screening visit greater than 1.5 x ULN
• Treatment with any other investigational product within 30 days prior to the first dose of study medication
• History or current evidence of alcohol or drug abuse within the last 12 months
• Prostate Specific Antigen (PSA) greater than 20ng/ml
• Use of suprapubic catheterisation after failed urethral catheterisation
• Neurogenic bladder dysfunction, confirmed or suspected, irrespective of etiology
• Isolated bladder neck disease
• Acute or chronic prostatitis
• Confirmed or suspected urethral stricture
• Known bladder stones
• Clot retention secondary to haematuria of any cause
• Patient unwilling to use a condom during sexual intercourse