Efficacy of oral administration of etidronate disodium in maintaining normal serum calcium levels in previously hypercalcemic cancer patients.

ABSTRACT

As part of a multicenter trial of etidronate disodium for control of hypercalcemia in patients with malignancies, patients achieving normocalcemia within seven days after starting intravenous therapy with etidronate disodium plus saline were enrolled into a double-blind, placebo-controlled trial of oral etidronate disodium to maintain normocalcemia. By random assignment, patients received either oral etidronate disodium, 20 mg/kg/day, or placebo for up to three months. Efficacy was evaluated after 30 days of maintenance therapy patients who were normocalcemic on day 30 were considered treatment successes. Of 81 patients who entered this phase of the study, 63 were evaluable for efficacy. Analysis of this group revealed that significantly (P less than 0.01) more patients in the etidronate disodium group (35%) than in the placebo group (6%) were normocalcemic at day 30. Life-table analysis of response indicated that patients treated with etidronate disodium maintained normocalcemia significantly (P less than 0.01) longer than did patients receiving placebo (median, 29 days versus 11 days). These results suggest that in patients whose calcium levels were normalized with IV etidronate disodium, oral etidronate disodium maintained normocalcemia significantly longer than no maintenance therapy in patients treated for hypercalcemia secondary to malignancy.