Abstract
Acyclovir is a widely used antiviral agent used to treat viral meningitis. Although well tolerated, on rare occasions, it can cause severe nephrotoxicity and neurotoxicity. It is recommended that the dose of intravenous acyclovir be calculated based on the ideal body weight for height rather than the actual weight in obese patients to avoid excessive dosage. We report two patients who developed severe acute kidney injury and neurological symptoms while on intravenous acyclovir therapy. The first patient was a 57-year-old obese woman known to have epilepsy who received a dose of intravenous acyclovir based on her actual weight of 80 kg and subsequently developed acyclovir-induced nephrotoxicity and increased seizure activity. The second patient was a 60-year-old, slightly overweight, man, who received a dose of intravenous acyclovir based on his actual weight of 80 kg and subsequently developed both acyclovir-induced nephrotoxicity and possible neurotoxicity. No other cause for the deterioration in renal function or neurological symptoms was identified, and there was rapid recovery within three days of stopping acyclovir therapy. This case report emphasizes the importance of monitoring renal function while patients are on intravenous acyclovir therapy and highlights the fact that even non-obese, overweight patients are at risk of toxicity when their actual body weight instead of their ideal body weight for height is used for intravenous acyclovir dose calculation.