Background: There have been several reports of acyclovir-induced renal failure, when the drug has been administered intravenously and/or associated with water restriction.
Case report: Case n. 1: A 14 year-old boy, was treated with intravenous acyclovir because of an acute encephalitis, possibly due to Herpes viral infection. The acyclovir dose was given erroneously high, 24 mg/kg, 3 times/day, with water restriction, 30 ml/kg/day. Creatininemia increased from 70 to 200 mumol/liter after 48 hours of treatment and was 426 mumol/liter after 5 days. It decreased within a few days after the acyclovir dose was reduced to 6 mg/kg/day and the water intake was increased to 80 ml/kg/day. Case n. 2: A 17 year-old girl was suffering from chronic renal failure due to bilateral kidney hypoplasia associated with hypertension (creatinine clearance: 40 ml/min/1.73 m2). She was given intravenous acyclovir, 20 mg/kg/day, with water restriction, 30 ml/kg/day, to treat acute meningoencephalitis, possibly due to Herpes infection. Creatininemia increased from 200 to 450 mumol/l within 8 days of treatment; it returned to initial values 5 days after cessation of acyclovir and rehydration.
Conclusion: These 2 cases confirm the risk of renal impairment when acyclovir is administered intravenously. The risk is greater after bolus injections and when high doses are used. Water restriction is an additional risk, as was the chronic renal insufficiency in our second patient. A scheme of acyclovir therapy based on initial values of creatininemia is mandatory.