Valacyclovir-Induced Seizures in End-Stage Renal Disease

[A Pharmacist's Query Avoiding Exacerbation of Adverse Effects in a Patient with Acyclovir Encephalopathy: A Case Report]

We report a haemodialysis patient with end-stage renal failure whom a pharmacist aided in the management of acyclovir (ACV) encephalopathy, which may have been related to valacyclovir hydrochloride (VACV) administered without sufficient dose reduction. The patient 78 years was admitted with a tentative diagnosis of varicella zoster viral meningitis. A pharmacist suspected ACV encephalopathy related to excessive VACV administration and raised a query with the attending physician. According to the pharmacist's proposal, ACV administration was discontinued and continuous hemodiafiltration (CHDF) was performed. On day 5 of hospitalisation, the consciousness disorder was improved. In this report, we showed the detailed CHDF conditions of the present case, and the contribution of a pharmacist to treating and avoiding ACV encephalopathy was discussed.

Neurotoxicity Associated with Standard Doses of Valacyclovir in Renal Insufficiency

Chronic kidney disease is a growing problem in the United States that increases the risk of medication-related complications. The antiviral medication valacyclovir hydrochloride is indicated for the treatment and/or suppression of herpes labialis, genital herpes, and herpes zoster and requires dosage adjustment for renal impairment. Valacyclovir is generally well tolerated, but serious adverse drug reactions have been reported including neurotoxicity and acute renal failure, especially in the elderly and in those with chronic kidney disease. We present 2 cases of neurotoxicity suspected to be secondary to non-renally dose-adjusted valacyclovir therapy. The first is a female hemodialysis patient who developed neuropsychiatric symptoms within 24 hours of initiating valacyclovir therapy; the second is an elderly gentleman with stage 4 chronic kidney disease and symptoms after 2 days of therapy. Both were prescribed valacyclovir 1 g orally 3 times daily despite renal impairment. Use of the Naranjo adverse drug reaction probability scale suggests probable associations between neuropsychiatric symptoms displayed by the patients and valacyclovir (score of 5 in case 1; score of 7 in case 2). These cases highlight the importance of considering renal status when dosing medications that undergo significant renal elimination.

Valacyclovir neurotoxicity: clinical experience and review of the literature

Valacyclovir (VACV) is used increasingly to treat herpes zoster, although neuropsychiatric symptoms [VACV neurotoxicity (VAN) or acyclovir neurotoxicity], may accompany use of this drug. To promote awareness of this rare condition, we describe here two clinical cases of VAN we previously reported and review 20 cases from the literature. In all cases, chronic or acute renal failure preceded VAN. The symptoms of VAN varied, but disturbances of consciousness and hallucination occurred most commonly. When acute renal failure was due to the drug, recovery from both the disturbance of consciousness and renal failure followed within several days after discontinuation of VACV. Early recognition and diagnosis will ensure effective treatment of VAN.