New approach to the treatment of hypercalcemia The effect of short‐term treatment with mithramycin

An intravenous bolus injection of mithramycin (25 μg per kilogram) was given to patients with malignancy‐related hypercalcemia persisting after hydmtion. In most instances a gradual but steady fall in the serum calcium occurred within the next 48 hours, accompanied by a fall in serum inorganic phosphate and 24 hour urinary calcium excretion. Patients with head and neck cancer, cancer of the lung, and multiple myeloma were somewhat less responsive as a group than patients with cancer of the breast or kidney. Aside from transient nausea and vomiting, side effects were minimal. Small doses of mithramycin inhibit bone resorption; dactinomycin and other RNA inhibitors block the action of vitamin D in vitro. The hypocalcemia following administration of these agents may be an expression of their antivitamin D action.