What is a renal safety concern associated with intravenous acyclovir, and what preventive measure reduces this risk?

• A. Crystal nephropathy; ensure adequate hydration and monitor urine output
• B. Hepatotoxicity; monitor liver enzymes
• C. Hyperkalemia; monitor potassium
• D. Acute tubular necrosis; administer diuretics

Answer: (A)

Acyclovir given IV can cause crystal nephropathy from the drug precipitating in the renal tubules, which can lead to an acute drop in kidney function if urine flow is insufficient. The key to preventing this is keeping urine output high by ensuring adequate hydration before and during the infusion, so the drug stays dissolved and doesn’t crystallize in the kidneys. Monitoring urine output and renal function helps catch issues early, and adjusting the dose or infusion rate in patients with reduced kidney function further lowers the risk. This hydration-focused approach is why the option describing crystal nephropathy and adequate hydration/urine output is the best fit.