Valacyclovir neurotoxicity in a patient with end-stage renal disease treated with continuous ambulatory peritoneal dialysis

Valacyclovir-associated neurotoxicity among patients on hemodialysis and peritoneal dialysis: A nationwide population-based study

Whether valacyclovir-associated neurotoxicity (VAN) occurs more frequently in patients with end-stage renal disease (ESRD) on dialysis is unknown. This is the first population-based study to examine the risk of VAN associated with ESRD patients on dialysis. Among 2,284,800 patients diagnosed as having herpes zoster from 2002 to 2016, patients with ESRD on dialysis and individuals with normal renal function were enrolled in this study. Following propensity score matching, we compared the risk of altered mental status between valacyclovir users and non-users in the ESRD and normal renal function cohorts over a 30-day follow-up period. In the ESRD cohort, the incidence of altered mental status was 1.68 and 0.52 per 1,000 person-day in valacyclovir users and non-users, respectively, with an adjusted hazard ratio (HR) of 3.22 (95% confidence interval [CI]: 2.04–4.99, P < 0.001). The incidence of altered mental status of valacyclovir users on hemodialysis (HD) and peritoneal dialysis (PD) was higher than that of non-users. The adjusted HR was 3.20 (95% CI: 1.98–5.15, P < 0.001) for those on HD and 3.44 (95% CI: 1.13–10.49, P = 0.030) for those with PD. However, altered mental status was not observed in patients on HD receiving ≤500 mg of valacyclovir three times per week or in those on PD receiving ≤500 mg of valacyclovir per day. The findings demonstrate that adjusting the valacyclovir dosage and monitoring VAN in patients with HD and PD who have herpes zoster is crucial.

[Acyclovir encephalopathy in a peritoneal dialysis patient despite adjusting the dose of oral acyclovir: a case report]

We report a case of acyclovir encephalopathy in a 77-year-old man who was introduced to peritoneal dialysis three years earlier. He developed herpes zoster and was treated with acyclovir (ACV) at 800 mg daily per oral. Two days later, he developed consciousness disturbance, hallucinations and asterixis. Acyclovir was stopped and continuous ambulatory peritoneal dialysis (CAPD) was switched to hemodialysis, which resulted in the resolution of his symptoms. Because the optimal dose of ACV varies among individuals depending on the bioavailability of ACV and metabolic enzyme activity, ACV encephalopathy can occur even when the acyclovir dose is modified according to the renal function of the affected patient. Because CAPD provides a poorer ACV clearance than hemodialysis, CAPD patients tend to have a higher risk of developing ACV encephalopathy and to recover more slowly. If CAPD patients develop ACV encephalopathy, a temporary change in the type of dialysis to hemodialysis should be considered.

Acyclovir Neurotoxicity in a Peritoneal Dialysis Patient: Report of a Case and Review of the Pharmacokinetics of Acyclovir

BACKGROUND The elderly population in the United States and the world is rapidly increasing. With aging, immunity and kidney function decrease, thus predisposing people to viral illnesses for which there is no effective prophylaxis. Herpes zoster afflicts the elderly and other immunocompromised patients, like those with end-stage renal disease, transplant recipients, and cancer patients, causing significant morbidity and sometimes mortality. Treating herpes zoster becomes problematic when the regular pharmacokinetics of the antiviral drugs are disturbed. CASE REPORT An 83-year-old African American man with end-stage kidney disease (ESRD) and on chronic peritoneal dialysis (PD) developed herpes zoster, for which he received the manufacturer-recommended intravenous dose of acyclovir. Shortly after taking the medication, he developed confusion, disorientation, and visual hallucinations. He was switched from PD to hemodialysis (HD), with successful recovery. Examination of the cerebrospinal fluid for meningitis and imaging studies of the head were negative. Serum levels of acyclovir were elevated. CONCLUSIONS Even when the acyclovir dose is properly adjusted for kidney function based on the current manufacturer's recommendations, it can cause neurotoxicity. Here, we discuss the pharmacokinetics of acyclovir and make some recommendations with regard to dose adjustment in patients with ESRD.

Bilateral herpes zoster in a patient with end-stage kidney disease

Herpes zoster (HZ) is caused by the reactivation of a latent varicella-zoster virus (VZV) infection within the cranial or dorsal root ganglia. The cutaneous lesions of HZ are typically limited to a single dermatome, while non-contiguous HZ involving two or more dermatomes is a very rare clinical entity. In this report, we describe a case of HZ involving the left and right side of the abdomen corresponding to the T11 dermatome in a 63-year-old man on chronic peritoneal dialysis. The characteristic cutaneous manifestation encouraged us to ascribe the disease to HZ duplex bilateralis, and the patient was given a single dose of oral valacyclovir and achieved a favorable outcome. The therapeutic concerns regarding the reactivation of VZV in patients with end-stage kidney disease are also discussed.

Intensification of peritoneal dialysis improves valacyclovir neurotoxicity

Valacyclovir induced neurotoxicity is a life-threatening complication, usually starting 24-48 h after drug-peak serum concentrations. The elderly with impaired renal function seem to be the most susceptible group to valacyclovir neurotoxicity. Although hemodialysis is considered the best method for rapid drug removal, our case showed that intensive peritoneal dialysis regimen leads to the recovery of neurotoxicity after 3 days.

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.

Pharmacokinetics of acyclovir and its metabolites in cerebrospinal fluid and systemic circulation after administration of high-dose valacyclovir in subjects with normal and impaired renal function

Valacyclovir, the L-valyl ester prodrug of acyclovir (ACV), is widely prescribed to treat infections caused by varicella-zoster virus or herpes simplex virus. Rarely, treatment is complicated by reversible neuropsychiatric symptoms. By mechanisms not fully understood, this occurs more frequently in the setting of renal impairment. We characterized the steady-state pharmacokinetics of ACV and its metabolites 9-[(carboxymethoxy)methyl]guanine (CMMG) and 8-hydroxy-acyclovir (8-OH-ACV) in cerebrospinal fluid (CSF) and the systemic circulation. We administered multiple doses of high-dose valacyclovir to 6 subjects with normal renal function and 3 subjects with chronic renal impairment (creatinine clearance [CrCl], approximately 15 to 30 ml/min). Dosages were 2,000 mg every 6 h and 1,500 mg every 12 h, respectively. Indwelling intrathecal catheters allowed serial CSF sampling throughout the dosing interval. The average steady-state concentrations of acyclovir, CMMG, and 8-OH-ACV were greater in both the systemic circulation and the CSF among subjects with impaired renal function than among subjects with normal renal function. However, the CSF penetration of each analyte, reflected by the CSF-to-plasma area under the concentration-time curve over the 6- or 12-h dosing interval (AUC(tau)) ratio, did not differ based on renal function. Renal impairment does not alter the propensity for ACV or its metabolites to distribute to the CSF, but the higher concentrations in the systemic circulation, as a result of reduced elimination, are associated with proportionally higher concentrations in CSF.

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.

The life-threatening complications of dermatologic therapies

Dermatologists use a variety of systemic drugs, some of which can cause severe adverse reactions and even fatalities. Ivermectin, a well-tolerated drug, can cause severe neurological side effects, whereas metronidazole, in high cumulative doses, has been associated with convulsions and rarely with hepatotoxicity. Dapsone is associated with frequent hematologic side effects, such as methemoglobinemia, hemolysis, and anemia. Although hepatotoxicity is rare and usually mild and reversible with the new antifungal agents, severe cutaneous reactions (such as toxic epidermal necrolysis, Stevens-Johnson syndrome, and anaphylaxis) have been reported. Even a relatively safe drug such as acyclovir has been reported to be the cause of renal failure and neurotoxicity. Retinoids can cause not so benign "benign" intracranial hypertension. Methotrexate can cause not only liver toxicity, but also myelosuppression and pancytopenia, which may be acute and life threatening. Nephrotoxicity is a well-recognized side effect of cyclosporine, whereas thrombotic thrombocytopenic purpura, which is associated with high morbidity and mortality, is less well known. Dermatologists should be familiar with these and other severe adverse reactions of the most popular and most used systemic medications of our trade.