Two cases of telbivudine-induced myopathy in siblings with chronic hepatitis B
A 25-year-old man who received telbivudine therapy for chronic hepatitis B presented with progressive generalized weakness and difficulty exercising. He was diagnosed with CHB 4 years ago, and took lamivudine at first, but he changed to combination therapy of 600 mg of telbivudine once daily for 13 months and 10 mg of adefovir once to control HBV activation and lamivudine resistance. At 12 months after starting treatment, the HBV DNA level decreased to the undetectable range, and the elevated serum AST and ALT levels also decreased along with viral stabilization. However, the patient began to suffer from generalized weakness and difficult exercising since about 2 years after the treatment. He did not have dysphagia, cramps, or sensory symptoms and did not exhibit motor weakness. Laboratory analyses showed AST of 54 IU/L, ALT of 57 IU/L, total bilirubin of 0.4 mg/dL, BUN of 13.4 mg/dL, and serum creatinine of 1.15 mg/dL, and serum CK was elevated up to 2,992 IU/L. In this case, we did not conduct EMG. These two patients were siblings and they started taking telbivudine at the same time. Also, his symptoms were similar to those of his brother. His brother was diagnosed telbivudine-induced myopathy in advance. He visited the department of neurology and was diagnosed with toxic myopathy. For these reasons, we empirically diagnosed this patient with telbivudine-induced myopathy and decided to switch telbivudine to entecavir, so he received combination therapy with 0.5 mg of entecavir and 10 mg of adefovir. Two months after telbivudine withdrawal, he revisited our clinic and his laboratory test showed decreased CK level to the normal range of 157 IU/L. Also, his clinical symptoms of muscle weakness have improved.