Valacyclovir neurotoxicity: clinical experience and review of the literature

Abstract

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.

Acute renal injury induced by valacyclovir hydrochloride: A case report

“…In addition to neurotoxicity, acute kidney injury is a well-described side effect of acyclovir administration, since crystal deposition may lead to the development of renal failure. In recent years, valacyclovir has largely replaced acyclovir in the treatment of herpes virus infections, because it is more effective by oral administration (7). There are several cases about the acute kidney injury caused by acyclovir reported, but the side effects of valacyclovir are not well recognized by clinicians, thus are rarely reported compared with acyclovir.…”

False-positive Results Obtained for Immunoglobulin M Antibody Tests of Cerebrospinal Fluid for Herpes Simplex Virus in a Patient with Varicella Zoster Virus Encephalitis

“…He had received oral valacyclovir and had a past history of chronic renal failure before the onset of disturbed consciousness, suggesting the possibility of valacyclovir neurotoxicity (VAN). While the symptoms of VAN usually appear within the first 72 hours of treatment, the average time between dermatological and neurological symptoms is approximately one week for VZV encephalitis (6). The presence of inflammatory cells in the CSF and detection of MRI abnormalities also suggest VZV encephalitis (7).…”

Safety profile of antiviral medications: A pharmacovigilance study using the Italian spontaneous-reporting database

“…lucination, anxiety, dysarthria, and ataxia. [40][41][42][43] A direct toxic effect has been hypothesized: In fact, increased concentrations of acyclovir and its main metabolite (9-carboxymethoxymethylguanine) have been found in the serum 44 and cerebrospinal fluid of acyclovir users with neuropsychiatric symptoms. 45 Lactic acidosis, acute renal failure, fever, and asthenia were other signal alarms identified by our analysis.…”