Effects of Mithramycin on Paget's Disease of Bone

SUMMARY

Administration of mithramycin (25 µg/kg/day for 10 days) to two patients with advanced Paget's disease of bone resulted in clearcut beneficial effects. The patients' symptoms were ameliorated. Serum calcium and phosphate levels were lowered during therapy but promptly returned to normal afterward. Markedly elevated serum alkaline phosphatase levels were reduced considerably and have remained relativly low after therapy. Urinary calcium and phosphate levels were also markedly reduced during therapy, and negative calcium and phosphate balances became positive. Markedly elevated urinary hydroxyproline levels were reduced to less than one fourth of control values. Bone accretion rates were significantly decreased.

These observations suggest that mithramycin administration diminished the elevated osteoclastic and compensatory osteoblastic activity characteristic of Paget's disease, and this agent may have therapeutic value in patients in whom there is wide dissemination of the pathologic process.