Aciclovir Administration Protocol
For adults with normal renal function, aciclovir should be administered intravenously at a dose of 10 mg/kg every 8 hours, with adequate hydration to prevent crystalluria and nephrotoxicity. 1, 2, 3
Dosing Recommendations
Standard Dosing for Adults
- Intravenous administration: 10 mg/kg every 8 hours 1, 2
- Duration: 14-21 days for HSV encephalitis 1, 2
- For VZV encephalitis: 10-15 mg/kg every 8 hours 1
Renal Adjustment
Aciclovir requires dose adjustment based on creatinine clearance:
- Normal renal function (CrCl >80 mL/min): 10 mg/kg every 8 hours 3
- CrCl 50-80 mL/min: Maintain standard dose with careful monitoring 3
- CrCl 15-50 mL/min: Reduce dose or extend interval 1
- CrCl <10 mL/min: Significant dose reduction required 1, 3
- Hemodialysis patients: Dose after dialysis 1
Administration Technique
Proper Administration
- Infusion method: Administer as a 1-hour infusion (not as rapid bolus) 3
- Hydration: Ensure adequate hydration before and during therapy to prevent crystalluria 1, 4
- Preparation: Dilute in compatible IV solution to appropriate concentration
Monitoring Requirements
- Renal function: Check at baseline, 2-3 times weekly during induction therapy, and every 1-2 weeks during maintenance 1
- Electrolytes: Monitor regularly, particularly in patients receiving high doses 1
- Neurological status: Assess for signs of neurotoxicity, especially in patients with renal impairment 4
Special Considerations
Prevention of Complications
- Nephrotoxicity risk: Aciclovir-induced nephropathy can affect up to 20% of patients, typically manifesting after 4 days of IV therapy 1
- Weight-based dosing: Calculate dose based on ideal body weight rather than actual weight in overweight or obese patients to prevent toxicity 4
- Drug interactions: Low plasma protein binding (9-33%) means displacement interactions are unlikely 3, 5
CSF Penetration
- Aciclovir achieves approximately 50% of plasma concentrations in CSF, making it effective for CNS infections 3, 6
Follow-up and Duration
- For HSV encephalitis, repeat lumbar puncture at 14-21 days to confirm CSF is negative for HSV by PCR 1
- If CSF remains positive, continue IV aciclovir with weekly PCR until negative 1
- Consider oral valaciclovir for extended treatment in select cases after initial IV therapy 1
Common Pitfalls
- Inadequate hydration leading to crystalluria and nephrotoxicity
- Incorrect weight-based dosing in overweight patients
- Failure to adjust for renal impairment
- Rapid bolus administration rather than proper infusion
- Delayed initiation of treatment beyond 48 hours, which significantly worsens outcomes in encephalitis 2
Aciclovir remains the cornerstone of therapy for herpesvirus infections, with established efficacy and a well-understood safety profile when administered correctly.