[Bezafibrate myopathy in two patients with chronic renal failure]

Case 1, a 60-year-old man and case 2, a 70-year-old man had several year history of chronic renal failure with hypertension and hyperlipidemia due to diabetes mellitus. Treatment of hyperlipidemia was started by oral bezafibrate intake 1,200 mg per day in case 1 and 400 mg per day in case 2 respectively. Three to fourteen days later, both patients noticed symmetrical muscle pain and weakness. Then the symptoms worsened and they were hospitalized. At the time of admission, both patients revealed weakness in the proximal muscles of their upper and lower limbs and the serum creatine kinase and myoglobin levels were remarkably elevated. Myoglobinuria was also noted. Routine light microscopic examination of biopsied quadriceps femoris muscles of two patients showed scattered necrotic muscle fibers, some of which were under phagocytosis. The symptoms of the patients were immediately resolved after the drug was discontinued. Serum concentration of bezafibrate was remarkably elevated during treatment. Thus the diagnosis was established as having bezafibrate induced myopathy and, as far as we know, this is the first report of bezafibrate induced myopathy in Japan. On the basis of the above description, bezafibrate may induce muscle damage if dose is excess over the renal capacity. Extreme caution is warranted when the patient is placed on bezafibrate and has renal dysfunction. Strict dose adjustment is necessary in taking account of renal function to avoid muscle damage including rhabdomyolysis.