Single infusion of neridronate (6-amino-1-hydroxyhexylidene-1,1-bisphosphonate) in patients with active rheumatoid arthritis: effects on disease activity and bone resorption markers.

Aims: The aim of this study was to assess the effects of a single infusion of the bisphosphonate neridronate (N) on parameters of inflammation and bone resorption in rheumatoid arthritis (RA).
Methods: Forty-five patients with active RA were randomly allocated on a double blind basis to receive a single intravenous infusion of either N 25 mg (15 patients), N 50 mg (15 patients), or placebo (15 patients). At baseline and after 7 and 21 days, we assessed the following: erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and Ritchie's articular index as indices of disease activity; and urinary free deoxypyridinoline (DPyr), N-telopeptide of type I collagen (NTx) and hydroxyproline (OHP) as indices of bone resorption.
Results: At day 7, N 25 mg significantly decreased ESR compared to N 50 mg (p=0.002), and CRP compared to placebo (p=0.036). With regard to bone resorption markers, at day 7, both N 25 mg and 50 mg compared to placebo significantly decreased NTx (p<0.0005 and p=0.003, respectively) and OHP (p=0.001 and p=0.004, respectively). At day 21, N 50 mg significantly decreased OHP compared to placebo (p=0.017). DPyr levels remained unchanged in the three groups.
Conclusions: N 25 mg and 50 mg exerted different effects on RA activity parameters, since only the lower dose significantly decreased ESR and CRP. Both doses of N inhibited bone resorption, with a transient, significant reduction in urinary NTx and OHP, but without any effect on DPyr.