9-carboxymethoxymethylguanine and Herpes-Zoster

Acyclovir (ACV)-associated encephalopathy is related to an increase in plasma levels of 9-carboxymethoxymethylguanine, an ACV metabolite, and is often reported in patients with renal dysfunction. We report a case of ACV-associated encephalopathy with rapid progression of renal dysfunction after oral administration of valacyclovir (VACV) and review literature of previous ACV-associated encephalopathy cases.. An 88-year-old man was diagnosed with herpes zoster. VACV (3000 mg/day) treatment was initiated. Serum creatinine (Cr) level was 0.80 mg/dL. However, irritability, memory impairment, and decreased responsiveness occurred after 3 days. The Cr level was 6.76 mg/dL on admission.. He was diagnosed with ACV-associated encephalopathy with acute kidney injury.. VACV was discontinued, hemodialysis was initiated on the day of admission, and then the signs and symptoms improved approximately 72 hours after the admission.. Worsening of renal function and encephalopathy should be a focus when using VACV or ACV, regardless of age and original renal function. Acute kidney injury and ACV-associated encephalopathy may particularly occur in the elderly even when renal function is normal. Therefore, regular monitoring of renal function and consciousness is necessary during VACV treatment.

Topics: Acute Kidney Injury; Aged, 80 and over; Antiviral Agents; Brain Diseases; Creatinine; Guanine; Herpes Zoster; Humans; Kidney; Male; Reference Values; Renal Dialysis; Valacyclovir

A 70-year-old man developed herpes zoster over the right L5-S2 region for 3 days and was admitted for acyclovir therapy. He had a medical history of rectal cancer status post-colostomy and end-stage renal disease undergoing thrice weekly hemodialysis. Without a prior loading dose, acyclovir 500 mg (7.7 mg/kg) daily was given intravenously in two divided doses. On the third dosage, the patient became confused and agitated and developed insomnia. Within the following 24 h, delirium, visual and auditory hallucinations, disorientation to place and time, as well as impaired recent memory occurred. At the same time, a transient low grade fever (38 degrees C) was noted but resolved spontaneously after ice pillow (Fig. 1). The etiology was vigorously explored. He had no history of any neurological or psychiatric disorders. Drug history was reviewed, but no other medications besides acyclovir were currently being used. Physical examination revealed neither meningeal signs nor focal neurological deficits. Serum blood urea nitrogen, glucose, and electrolytes were within normal limits except for an elevated creatinine level at 6.2 and 5.7 mg/dl (before and after neuropsychotic symptoms, respectively). Complete blood count with differentiation was also unremarkable. Cerebrospinal fluid examination was not possible as the patient's family refused the lumbar puncture. Moreover, an electroencephalograph study and head computed tomography scan disclosed no abnormalities. Acyclovir-induced neurotoxicity was suspected. Therefore, acyclovir was discontinued. Subsequently, serum acyclovir and CMMG were checked by enzyme-linked immunosorbent assay. Serum acyclovir level was 1.6 mg/l (normal therapeutic level, 0.12-10.8 mg/l) and CMMG level was 5 mg/l. Emergent hemodialysis (4-h/session) was given; the neuropsychotic symptoms, including agitation, delirium, and visual and auditory hallucinations, greatly abated after the second session. The patient fully recovered after three consecutive days of hemodialysis; the serum was rechecked and revealed that the acyclovir level was below 0.5 mg/l and the CMMG level was undetectable. At the same time, his herpetic skin lesions resolved well.

Topics: Acyclovir; Aged; Antiviral Agents; Delirium; Guanine; Hallucinations; Herpes Zoster; Humans; Kidney Failure, Chronic; Male; Renal Dialysis

Acyclovir (ACV) has been used for over two decades to treat herpes virus infections. Serious neurological adverse side effects have occurred during ACV treatment in patients with renal failure, but the cause of the symptoms remains unknown. We hypothesized that increased concentrations of the ACV main metabolite 9-carboxymethoxymethylguanine (CMMG) correlated to these symptoms.. We conducted an observational study from 1991 to mid 1999 based on samples sent for analysis of ACV concentration from various hospital departments in Sweden. Patients with neuropsychiatric symptoms (NS+, n=49) were compared with patients without symptoms (NS-, n=44). ACV and CMMG concentrations were analysed by HPLC. Medical records were analysed for symptoms and compared with pertinent cases identified from Medline.. The serum CMMG levels were significantly higher in the NS+ group (mean=34.1 micro mol/l, 95% confidence interval 23.4-46.1) compared with the NS- group (mean=4.7 micro mol/l, 95% confidence interval 3.3-6.6; P<0.001). CMMG was the strongest predictor in a receiver-operating characteristics curve analysis (ROC), based on 77 patients, of ACV-related neuropsychiatric symptoms. The ROC curve for CMMG demonstrated that neuropsychiatric symptoms could be predicted with a sensitivity of 91% and a specificity of 93% with the use of a cut-off value of 10.8 micro mol/l of CMMG. Thirty-five of 49 patients in the NS+ group showed levels exceeding this concentration compared with only three of 44 of patients in the NS- group (P<0.001). ACV exposure, ACV concentration, creatinine clearance and creatinine concentration were weaker but statistically significant predictors. Haemodialysis reduced CMMG and ACV levels and relieved the symptoms.. The determination of CMMG levels in serum may be a useful tool in supporting the diagnosis of ACV-associated neuropsychiatric symptoms. Furthermore, the monitoring of CMMG levels may prevent the emergence of symptoms.

Topics: Acyclovir; Adult; Aged; Antiviral Agents; Creatinine; Female; Guanine; Herpes Zoster; Humans; Kidney Failure, Chronic; Male; Mental Disorders; Middle Aged; Neurotoxicity Syndromes; ROC Curve; Sensitivity and Specificity