ABSTRACT
BACKGROUND: Valaciclovir (VAL) is the L-valyl ester of acyclovir and it is quickly hydrolysed to acyclovir. Acyclovir-related nephrotoxicity is associated with high drug infusion doses and VAL-related neurotoxicity to pre-existing renal failure. We observed two geriatric patients with normal serum creatinine who developed acute renal failure (ARF) and neurotoxicity after ingesting the drug at the conventional therapeutic dose. CASE REPORTS: The first patient was a 77-year-old female admitted to the intensive care unit because of anuria associated with coma and respiratory insufficiency. Baseline serum creatinine (Scr) was 0.9 mg/dL. Four days previously she had started VAL 1 g/bd for cutaneous HZ. Scr was 7 mg/dL and urinary output was <100 cc/24 h. The patient was ventilated and hemodialysis (HD) was started. After 6 days her urinary output increased and dialysis was discontinued. Two weeks after admission, Scr was 1.5 mg/dL, ventilation was discontinued and her consciousness level was normal. The second patient was a 73-year-old male. Baseline Scr was 0.7 mg/dL. He started VAL 1 g/TD because of hepatic cheratitis. After 4 days, he developed oliguria and stupor. At admission, Scr was 5.5 mg/dL, potassium was 6 mEq/L and the patient was unconscious. After drug withdrawal the diuresis increased and his consciousness level returned to normal. After 7 days Scr was 0.9 mg/dL. COMMENT: The clinical evolution suggested that the syndrome was related to the antiviral therapy. ARF preceded neurotoxicity. We suggest that high bioavailability, reduced glomerular filtration rate (GFR) related to age, and possibly the simultaneous ingestion of other drugs could have caused these side effects. We recommend the emphasis on potential side effects of antiviral therapy when treating geriatric patients even if Scr is in the normal range.
