Bezafibrates cause moderate, reversible impairment in renal function in patients without prior renal disease

Background/Aims: To determine whether bezafibrates have adverse effects on renal function. Methods: (1) A 3-year retrospective survey of 526 patients who were on bezafibrate for a while and 614 controls following fluctuations of serum creatinine levels. (2) A prospective study on 33 patients with previous evidence of bezafibrate-induced elevation in serum creatinine. The patients were examined after 3 months on bezafibrate 400 mg/day and then after 3 months without bezafibrate. Eight patients repeated the tests after 3 months on bezafibrate 200 mg/day. Results: Retrospective: 295 bezafibrate-treated patients (56%) and 67 controls (11%) demonstrated fluctuations ≥ 0.2 mg/dl in serum creatinine levels (p < 0.001); 113 patients (21%) and 16 controls (3%) showed fluctuations ≥ 0.3 mg/dl (p < 0.001). Prospective: bezafibrate 400 mg/dl increased serum creatinine from 1.16 ± 0.19 to 1.42 ± 0.2 mg/dl (p < 0.001) and urea from 37 ± 8 to 44 ± 8 mg/dl (p < 0.001); creatinine clearance (C_cr) decreased from 104 ± 23 to 82 ± 27 ml/min (p < 0.001). CPK increased from 82 ± 32 to 130 ± 58 mg/dl (p < 0.0001) and urinary myoglobin increased from 95.4 ± 21 to 199 ± 99 mg/dl (p < 0.0001). The 8 patients given bezafibrate 200 mg/dl experienced similar dose-dependent changes. Conclusions: Bezafibrate causes quiet common, dose-dependent and reversible changes in serum creatinine in patients with normal renal function, associated with a significant increase in serum CPK and urine myoglobin, suggestive of drug-induced mild subclinical skeletal muscle injury compromising renal function.