Efficacy of non-steroidal anti-inflammatory drugs on zoledronic acid-induced acute-phase reactions: randomized, open-label, Japanese OZ study

Introduction Zoledronic acid infusion is used to treat osteoporosis but patients, especially Japanese patients, often experience acute-phase reactions (APRs). In this multicenter, randomized, open-label, parallel-group study, we examined the efficacy of the most commonly used non-steroidal anti-inflammatory drug loxoprofen in Japan in reducing the incidence rate of zoledronic acid-induced APRs and body temperature, and investigated risk/protective factors for APRs in this population. Materials and methods Patients aged ≥ 60 years with primary osteoporosis ( n = 368) were allocated randomly to zoledronic acid plus loxoprofen (ZOL + LOX) or zoledronic acid alone (ZOL). All patients received 5-mg zoledronic acid infusion on day 1, and patients in the ZOL + LOX group also received 120 mg and 180 mg of oral loxoprofen on days 1 and 2, respectively. Adverse events and body temperature were recorded during the 7-day observation period. Results The incidence rates of APRs were 34.4% (64/186 patients) and 47.8% (87/182 patients) in the ZOL + LOX and ZOL groups, respectively ( P = 0.0109). The proportions of patients with increased body temperature (≥ 1 °C and ≥ 37.5 °C) were similar in both groups ( P = 0.1186). Past bisphosphonate users had a significantly lower incidence rate of APRs than treatment-naïve patients (odds ratio 0.444, 95% confidence interval 0.285–0.692, P = 0.0003). Conclusions Zoledronic acid-induced APRs appeared to be suppressed by loxoprofen. Known risk/protective factors, including prior osteoporosis treatment, were applicable to Japanese patients.