 The objective of MER-101-03 is to examine the effects of two different dosing regimens of MER-101 20mg tablets versus Zometa 4mg IV infusion once-monthly therapy. The effects will be monitored on a weekly basis by measuring various markers of bone metabolism. Patients to be enrolled will be those who have not received any previous bisphosphonate therapy. The study will be carried out on prostate cancer patients who are no longer on hormone therapy. Treatment in the study will be for a 2-month period. 