[Dichloromethylene diphosphonate (Cl2MDP) treatment of hypercalcaemia produced from bone metastases (author's...

Cl2MDP, a potent inhibitor of osteoclast-mediated bone resorption, was tested in 8 patients with malignant hypercalcaemia. In a 2 months' double-blind, cross-over study the patients received Cl2MDP (3200 mg/day) during 4 weeks and a placebo during 4 weeks in a randomized sequence. The serum Ca level fell from a mean pre-trial value of 12.2 +/- 1.7 mg/dl to 10.3 +/- 1.4 mg/dl after 4 weeks of Cl2MDP (p = 0.01). Reduction was rapid, with a mean serum Ca value of 10.5 +/- 1.4 mg/dl as early as the 3rd day. At the end of the Cl2MDP treatment, 6 out of the 8 patients had normal serum Ca levels. Following active treatment, the serum Ca level significantly increased in 2 patients and remained low in one patient under placebo. Treatment with Cl2MDP resulted in a decrease in calciuria from 397 +/- 193 mg/g creatinine/24 hours to 241 +/- 211 mg/g creatinine/24 hours (p = 0.05), but there was no decrease in hydroxyproline. Serum phosphorus and PTH levels remained normal. It is concluded that Cl2MDP is an effective and convenient oral treatment of hypercalcaemia due to bone metastases.