Background: Systemic sclerosis [SSc] is associated with increased risks of osteoporosis and fragility fracture. Oral
bisphosphonates is contraindicated in SSc patients due to increased risk of esophagitis. Although 5 mg intravenous zoledronic acid [Zol] has been approved for treatment of osteoporosis; however, using this drug is often limited due to its high cost and medical reimbursement limit in Thailand.
Objective: To examine the effect of Zol (4 mg) on bone mineral density [BMD] and bone turnover markers in SSc patients with osteoporosis.
Materials and Methods: An open-labeled study was designed. SSc patients with osteoporosis from Scleroderma Clinic, Khon Kaen University, Thailand were recruited. Lumbar spine and total BMD, and spinal radiography were performed at baseline and 12 months. Serum N-terminal propeptide of type I Pro-collagen [P1NP] and C-telopeptide of type I collagen [CTX] were evaluated at 0, 3, 6, and 12 months after treatment.
Results: Twenty-six patients were recruited for the final analysis. At 12 months, Lumbar spine BMD increased significantly with Zol (6.76%, p<0.001), while total hip BMD was improved but not reach the statistical significance when compared with baseline (4%, p = 0.272). Both P1NP and CTX decreased significantly at 3 months and sustained to 12 months when compared with baseline. There was no new or worsening fractures during the study. Minor adverse events were observed but transient and were resolved within a few days.
Conclusion: Single infusion of 4 mg Zol increased the lumbar spine BMD and reduced bone turnover markers in SSc patients
with osteoporosis. This finding suggests that low dose Zol (4 mg) might be an alternative treatment for osteoprosis in SSc
patients.

Keywords: Osteoporosis, Systemic sclerosis, Zoledronic acid