Acyclovir Use in Infants

Indications and Treatment

The Centers for Disease Control and Prevention recommends acyclovir as the drug of choice for treatment of HSV infections in infants and children, regardless of HIV-infection status 1, 2
For neonatal HSV disease, high-dose intravenous acyclovir (20 mg/kg body weight/dose three times daily) is recommended for 21 days 1, 2
For skin, eye, and mouth HSV disease in neonates, intravenous acyclovir should be administered for 14 days 1, 2
For symptomatic HSV gingivostomatitis in infants, either intravenous acyclovir (5-10 mg/kg/dose three times daily) or oral acyclovir (20 mg/kg/dose three times daily) for 7-14 days is recommended 1, 2

Acyclovir therapy should not be discontinued in neonates with CNS disease unless a repeat CSF HSV DNA PCR assay is negative at day 19-21 of treatment 1, 2
Acyclovir is primarily excreted by the kidney; dose adjustment based on creatinine clearance is needed in patients with renal insufficiency 1, 2
Monitoring for neutropenia is recommended, as it was observed in 46% of infants receiving long-term oral acyclovir therapy, though it was generally self-limited 1, 2

For acyclovir-resistant HSV infections, intravenous foscarnet (120 mg/kg/day in 2-3 divided doses) is recommended until the infection resolves 2
Foscarnet should be administered slowly over 2 hours (or no faster than 1 mg/kg/minute) with saline fluid loading to minimize renal toxicity 2

Delaying treatment beyond 24 hours of symptom onset significantly reduces efficacy 3
Not adjusting dosage in the presence of renal impairment is a common pitfall to avoid 1, 2