RATIONALE: Paricalcitol may cause multiple myeloma cells to look more like normal cells, and to grow and spread more slowly. Paricalcitol may also stop the growth of the cancer cells by blocking blood flow to the cancer. Zoledronate may delay or prevent bone metastases in patients with multiple myeloma. Giving paricalcitol together with zoledronate may be an effective treatment for multiple myeloma or other plasma cell disorders.