Pediatric Herpes Simplex Virus Infection Medication

Updated: Feb 27, 2019
  • Author: J Michael Klatte, MD; Chief Editor: Russell W Steele, MD  more...
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Medication Summary

Antiviral agents used to treat herpes simplex virus infections are nucleoside analogs. Acyclovir is the antiviral most commonly used to treat herpes simplex virus (HSV) infections. Other oral medications include famciclovir, which is a prodrug that is converted to penciclovir, and valacyclovir, which is a prodrug that is converted to acyclovir. Oral therapy is effective for non–life-threatening herpes simplex virus infections (eg, primary orolabial, genital), and can be useful in the suppression of recurrent genital herpes simplex virus infections to diminish viral shedding and decrease rates of clinical recurrences. Intravenous (IV) acyclovir is indicated for the treatment of encephalitis, any form of neonatal disease, severe infection in patients who are immunocompromised, and occasionally for cases of severe orolabial or genital disease. [11, 12, 13, 14]


Antiviral agents

Class Summary

Acyclovir, a synthetic acyclic purine nucleoside analog, is the standard treatment for herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2) infections. Activation of the drug requires 3 phosphorylations. Herpes simplex virus thymidine kinase adds the first phosphate. Acyclovir binds 200-300 times more avidly to viral thymidine kinase than to host enzyme. After final cellular phosphorylation, the nucleoside triphosphate effectively inhibits DNA polymerase and acts as a DNA chain terminator. Precursors of acyclovir (ie, valacyclovir, famciclovir) have bioavailability better than that of their active metabolites (acyclovir and penciclovir, respectively). The bioavailability of valacyclovir ranges from approximately 42-64%, while that of acyclovir is between 10-20%. [75]  

The results of a multicenter, retrospective, cohort study suggest that delayed initiation of acyclovir therapy was associated with significantly greater odds of death in neonates with HSV infection. [76]

Acyclovir (Zovirax)

Inhibits activity of HSV-1 and HSV-2. Patients experience least pain and fastest resolution of cutaneous lesions with prompt start of therapy, usually within 48 h after rash onset. Selectively incorporated into infected cells. May prevent recurrent outbreaks. Long record of use with excellent safety profile.

Available as PO susp 200 mg/5 mL, tab, cap, injection, and topical formulation. Topical form does not appear to be effective in recurrent mucocutaneous or genital HSV infections and offers no advantage over PO form in treating primary genital HSV infections. For obese patients, calculate IV dose according to ideal body weight.

Valacyclovir (Valtrex)

Prodrug rapidly converted to active drug acyclovir. More expensive but more convenient dosing regimen and superior bioavailability than that of PO acyclovir. Use in adolescent HSV infection. Available as 500 mg and 1g tablet formulations. 

Famciclovir (Famvir)

Transformed in vivo to active nucleoside analogue penciclovir, which can effectively inhibit HSV DNA synthesis and/or replication. More expensive but more convenient dosing regimen than that of acyclovir. Use in adolescent HSV infection.

Penciclovir (Denavir)

1% cream approved for treatment of recurrent orolabial HSV infection. Nucleotide derivative active in vitro against HSV-1 and HSV-2. Guanosine analog that inhibits viral DNA synthesis. Negligible systemic absorption after topical use. Repeated application of cream beginning shortly after onset of recurrent HSV symptoms and continued for 4 d shortens healing time to about 1 d. May also shorten duration of viral shedding. Not approved by the FDA for use in children.