What is the recommended dosing interval for acyclovir in neonates?

• A. Every 6 hours
• B. Every 8 hours
• C. Every 12 hours
• D. Every 24 hours

Answer: (B)

Neonatal antiviral dosing is tuned to how newborn kidneys handle drugs, so the interval is set to maintain effective drug exposure without causing buildup. For HSV in neonates, the standard regimen is 60 mg/kg per day of acyclovir given IV in divided doses every 8 hours (20 mg/kg per dose). This every-8-hours schedule balances achieving therapeutic levels to suppress viral replication with the immature renal clearance in neonates, minimizing the risk of nephrotoxicity from accumulation. Dosing more frequently, like every 6 hours, would raise total daily exposure and potential toxicity; dosing less frequently, such as every 12 or 24 hours, could leave drug levels subtherapeutic and allow ongoing viral activity.