[Severe central nervous system symptoms following oral administration of acyclovir in a patient with chronic renal failure: a case report].

A case of renal failure in a patient with severe central nervous system symptoms during oral acyclovir medication is reported. A 68-year-old man maintained on hemodialysis was given oral acyclovir 4,000 mg daily in divided doses because of herpes zoster affecting the left C3/5 dermatomes. He had vomiting and confusion 36 hours after administration. He had no focal neurological signs. The symptoms resolved 4 days after cessation of acyclovir administration and blood purification every day. Because of its high therapeutic index the use of acyclovir is associated with few side effects. In patients with renal failure the half-life of acyclovir is prolonged, this report indicates the importance of adhering to the dosage reductions in patients with renal failure.