The primary objective is to assess the safety of GI198745 0.05mg, 0.5mg, 2.5mg once daily for 52 weeks.

Upon completion of 24 weeks of GI198745 0.05 mg, 0.5 mg, 2.5 mg, or placebo therapy in study ARI20005, subjects are enrolled into an extension phase and are continued on the same therapy once daily for up to further 28 weeks, followed by up to 16 weeks of post-dosing assessments.

Inclusion Criteria:

• Has been receiving the investigational product for at least 20 weeks in the preceding dose finding study and the investigator or subinvestigator has confirmed the tolerability and has judged as appropriate to participate continuously in further 28 weeks treatment.

Exclusion Criteria:

• Is withdrawn from the dose finding study.
• Has less than 75% compliance with the investigational product in the dose finding study at given the informed consent for the long-term extension study.
• Has a prostate cancer at giving informed consent for participating in the long-term extension study; or is suspected to have a prostate cancer in palpation, ultrasound imaging, biopsy, etc. at giving informed consent for participating in the long-term extension study.
• Has the post void residual volume > 250 ml at starting the long-term extension study. (as measured by suprapubic ultrasound).
• Has chronic bacterial prostatitis or chronic urinary tract infections during the dose finding study
• Has acute urinary retention in the dose finding study.
• Has a history or current evidence of drug or alcohol abuse during the dose finding study
• Has been treated with any investigational product including post-marketing clinical trials during the dose finding study.
• Has myocardial infarction, coronary arterial bypass surgery, unstable angina, arrhythmia, congestive heart failure, cerebrovascular accident during the dose finding study.
• Has any concurrent disease or complication that, in the opinion of the investigator/sub-investigator, is difficult to evaluate efficacy of GI198745 in this study and that might poses additional risk to the patient.
• Is actively trying to procreate in the study period.
• Is unsuitable for this study, in the opinion of the investigator/sub-investigator.