Paget's disease of bone was first described by Sir James Paget, an English surgeon, in 1876.1 Despite numerous attempts, no effective treatment for the disorder was found for almost a century. We described one of the first effective agent (mithramycin, now named plicamycin to avoid confusion with mitomycin) against the disease in 1968.2 Subsequently, within the next few years, two additional classes of agents were introduced. Calcitonins—first porcine, then salmon, and then human—were followed by the near simultaneous introduction of the bisphosphonates, of which sodium etidronate (1, hydroxyethylidene-1, 1-bisphosphonate [formerly known as EHDP]) is the most familiar. The use of porcine calcitonin was abandoned because of a lack of potency, but salmon calcitonin (Calcimar) and human calcitonin (Cibacalcin) have proved useful therapeutically, as has sodium etidronate (Didronel). Sodium etidronate is generally more potent in disease suppression than are the calcitonins, but it has the disadvantage of tending to