Effect of multiple intravenous pamidronate courses in Paget's disease of bone

Pamidronate is a bisphosphonate whose short-term biological efficacy in Paget's disease of bone was convincingly established many years ago. A less well studied area is the efficacy of pamidronate in slowing disease progression and in preventing and treating complications.

We conducted an uncontrolled retrospective study of 79 Paget's disease patients given multiple intravenous pamidronate courses over a mean period of 45 +/- 19 months. The pamidronate dose per course was 180 mg, usually given over three days. The disease was severe and in some cases had proved refractory to other medications. Reasons for pamidronate therapy were pain or other subjective symptoms; established bone, joint, or nervous system complications; or prevention or these complications in patients with involvement of high-risk sites.

Bone and joint pain improved under therapy, and in 78% of cases the outcome in terms of complication treatment and/or prevention was favorable. An important finding was waning of the clinical and biological effects of pamidronate as the number of courses increased. Fourteen percent of patients developed resistance to pamidronate, which seemed more closely related to disease extension than to focal lesion activity.

These data suggest that a prompt return to normal of laboratory markers, most notably total alkaline phosphatase, should be sought, if needed by using higher doses than in our study.