Myotoxicity of telbivudine in pre-existing muscle damage

A 27 yo male of African origin received telbivudine for hepatitis B during 3 months. Three weeks after initiation of the drug he developed myalgia, and tiredness. Creatine-kinase increased from 278 U/l (n, <170 U/l) at baseline to 3243 U/l. Shortly after discontinuation of telbivudine muscle symptoms and hyper-CK-emia disappeared. The findings suggest that pre-existing muscle damage favored the myotoxic effect of telbivudine.Telbivudine appears to cause accelerated muscle toxicity if given to patients who already have muscle damage. Patients under telbivudine should be closely monitored for muscular side effects and those with pre-existing muscle damage should not receive the drug.Telbivudine has been reported to cause moderate hyper-CK-emia in 9-12% of the treated patients [1,2]. The following case is important because it indicates that hyper-CK-emia from telbivudine occurs predominantly in patients with pre-existing subclinical muscle damage.The patient is a 27 yo HIV-negative male of African origin with a language barrier and a history of inactive hepatitis C, right-sided omalgia, a single episode of a polymorphic psychosis at age 26 y, mild chronic renal insufficiency (creatinine: 1.2 mg/dl (n, <1.1.mg/dl)) at least since age 25 y, mild recurrent hyper-CK-emia, leucopenia, and thrombopenia, recurrent abdominal pain presumably from chronic pancreatitis, and hyper-gammaglobulinemia (table 1). His family history was negative for neuromuscular disorder.At age 24 y hepatitis B was diagnosed. The patient received various antiviral therapies, such as lamivudine, adefovir dipivoxil, and fenofovir always for a short time because of low compliance, but effectively reducing the virus load as long as he agreed to take the drug. In April 2009 a therapy with telbivudine was started without performing a pre-treatment resistance test. Three weeks after initiation of telbivudine the patient experienced myalgias and tiredness. Although creatine-kinase (CK) had been elevated at le