Background Zoledronic acid is a commonly used intravenous bisphosphonate. Predominantly it is excreted through the kidney. Use of zoledronic acid is contra-indicated in patients with eGFR of <30. Effect of zoledronic acid on kidney function after repeated infusions in a real life scenario is not well described. Zoledronic acid related hypocalcaemia is well recognized. But frequency of this complication in real life and its link to renal function has not been studied.
Objectives The aim of our study was to assess the effect of zoledronic acid on the renal function, calcium level and link between renal function and calcium level in patients treated with yearly zoledronic acid infusion for primary or secondary prevention of fractures in osteoporosis.
Methods A retrospective review of patients receiving zoledronic acid infusions between August 2008 and August 2015 was carried out. Patients receiving the treatment for osteoporosis and who had received at least one infusion were included. All the patients had calcium level and renal function measured before and a week after the infusion. Calcium level >2.5 mMol/L was considered elevated and <2.1 as low. The e GFR measures were classified into categories of >60 (normal), 45–59 (mild impairment) and 30–44 (moderate impairment). Pre and post infusion calcium values were matched to assess the effect on the calcium. Parametric analysis was carried out to compare the means.
Results 200 patients were identified on the database. 175 patients were analysed based on our inclusion criteria. 175 patients received 354 infusions. Baseline eGFR, calcium and post infusion eGFR and calcium levels are detailed in the table below. There was no significant difference between pre and post infusion eGFR or calcium levels. We also did not find any significant correlation between baseline eGFR and post infusion calcium level.
Conclusions 1. Only one patient's post infusion eGFR dropped to 28.4 after the second infusion. This improved to baseline a week later.
2. Only one patient had calcium below 2.1 post infusion (1.91). The post infusion calcium returned to normal after a week.
3. There was no significant drop in post infusion eGFR compared to baseline particularly in those who had mild or moderate renal impairment.
4. Calcium level did not come down significantly following zoledronic acid infusion.
5. Baseline eGFR had no significant effect on post-infusion calcium level.
6. This real life experience reinforces the safety of zoledronic acid infusion outside trial environment.
Bonnen S, Sellmeyer DE et al. Renal safety of annual zoledronic acid infusions in osteoporotic postmenopausal women. Kidney Intl, 2008 vol 74(5):641–8
Munier A, Gras V etal. Zoledronic acid and renal toxicity: data from French adverse event reporting database. Ann Pharmaco, 2005 vol (7–8):1194–8
Rice A, Roche S et al. The effect of IV zoledronic acid on renal function and serum calcium in an osteoporotic population. Osteoporosis Intl, vol/is 26/1 suppl 1 (S313–4)
Disclosure of Interest None declared