Pamidronate and Zoledronic Acid in the Treatment of Paget's Disease of Bone

Paget's disease of bone (PDB) is a condition characterized by excessive and abnormal bone remodelling. Due to a high rate of bone remodelling, bisphosphonates, and especially pamidronate and the newer zolendronate, are indicated in the treatment of PDB. The presence of asymptomatic, but active PDB represents an indication for treatment aimed at preventing later complications. An additional indication for treatment is the involvement of skeletal segments that may give rise to severe complications. Pamidronate has a long history in the treatment of PDB. The more utilised regimen is 3 to 6 i.v. infusion of 60 mg of pamidronate at an infusion rate of 1 mg/min within 3-21 days. Zolendronate (5 mg once yearly) is the most powerful amino-bisphosphonate currently used. This primacy recognizes both the ability to inhibit the farnesyl-pyrophosphate synthetase and the higher affinity to hydroxyapatite crystals as a cause. Both pamidronate and zolendronate are effective in PDB, with an evidence-based superiority of the latter.