An open study of pamidronate in the treatment of refractory ankylosing spondylitis.

OBJECTIVE

Bisphosphonates inhibit the development of delayed type hypersensitivity chronic inflammation and suppress inflammation and cartilage/bone erosion in diverse murine arthritis models. We evaluated antiinflammatory properties of the bisphosphonate pamidronate in patients with ankylosing spondylitis (AS) refractory to nonsteroidal antiinflammatory drugs.

METHODS

Patients included 14 men and 2 women. The first group of 8 patients (Group 1) received pamidronate as a 30 mg intravenous infusion once a month for 3 months, followed by a 60 mg dose once a month for an additional 3 months. Eight additional patients (Group 2) received only the 60 mg dose once a month for 3 months. Clinical assessments included the BASDAI (Bath AS Disease Activity Index), BASFI (Functional Index), and BASMI (Metrology Index), and laboratory assessments hemoglobin and erythrocyte sedimentation rate (ESR) at baseline and one month after final 60 mg dose of pamidronate. Mean BASDAI score at study entry was 6.7 for both groups.

RESULTS

A significant improvement was observed in disease activity score in Group 1 after 6 monthly infusions of pamidronate (mean BASDAI 4.21; p = 0.03), in the BASMI score (p = 0.01), and the ESR (p = 0.009). A significant improvement in the BASMI was noted in Group 2 patients (p = 0.007) after 3 monthly infusions of pamidronate, but not in the BASDAI score (mean 5.01; p = 0.07) or the ESR (p = 0.12).

CONCLUSION

Preliminary data suggest pamidronate may possess antiinflammatory activity in patients with AS, particularly with prolonged administration; this agent deserves further evaluation in a controlled trial.