What is a recommended preventive measure with intravenous acyclovir to reduce the risk of crystal nephropathy?

• A. Increase dose
• B. Co-administer diuretics
• C. No hydration
• D. Adequate hydration and monitor urine output

Answer: (D)

Crystal nephropathy from intravenous acyclovir happens when drug concentrates in renal tubules and can crystallize, potentially blocking flow and harming kidney function. The most effective preventive measure is ensuring adequate hydration and closely monitoring urine output. Keeping the patient well hydrated increases urine production, which dilutes the drug and helps flush any crystals out of the tubules, reducing the chance of precipitation. In practice, provide IV fluids (often isotonic saline) around the time of acyclovir administration and continuously monitor urine output and renal function to catch any early signs of nephrotoxicity. Increasing the dose or withholding hydration would raise the risk, and diuretics don’t replace the protective effect of maintaining good hydration.