Case Presentation: A 57 years old female with insignificant past medical history presented to emergency department for right sided chest and back pain for one week that was associated with skin lesions under right breast and adjoining area on the back consistent with herpes zoster rash. She also reported epigastric pain, nausea and vomiting. She has been taking Valtrex for a week. The physical examination revealed herpes zoster rash under right breast and adjoining back area. No hepatomegaly was appreciated. Pertinent laboratory findings included markedly deranged liver function tests (LFTs). The initial values were ALT: 1177, AST: 878, ALP: 348, gGTP: 1379, total bilirubin: 1.71 and direct bilirubin: 1.41. Patient was admitted for monitoring due to risk of fulminant liver failure. Ultrasound of abdomen showed mild hepatic steatosis. CT scan revealed moderate common bile duct dilatation, mild intrahepatic duct dilatation with no new liver lesions. Laboratory testing for Hepatitis (A,B,C), EBV, CMV, HIV, and autoantibodies was negative. Valtrex was switched to intravenous Acyclovir. Repeat blood work after discontinuing the Valtrex showed ALT:545, AST:95, ALP: 250 and total bilirubin: 0.56. Patient’s condition improved and she was discharged in stable condition.
Discussion: The mechanism of action of Valtrex involves conversion to acyclovir which has shown antiviral activity against Herpes Simplex Virus and Varicella Zoster Virus by stopping viral DNA replication. Valtrex side effects on hepatobiliary tract are mostly limited to mild to moderate asymptomatic elevation of liver enzymes that does not require drug suspension. But severe hepatoxicity rendering hospital admission is still rare. Valtrex was believed to be the culprit drug in this case as the patient’s LFTs showed improvement by discontinuing the drug.
Conclusions:
Valtrex side effects can involve severe hepatotoxicity and it can be discontinued in such cases to avoid fulminant hepatitis and irreversible liver damage.