Treatment phase All injections will be administered by the investigator or co-investigators for the entire study. Fasting (10 hours) blood samples will be taken (immediately before giving the injections) every time subjects come for injections (week 0, 6, 18, 30 and 42) and at the end of the treatment phase. On these occasions, a physical examination including weight, blood pressure and pulse rate checks will be performed. Volunteers will be asked to complete a sexual and behavioral questionnaire and a pain questionnaire during these visits.