What is the role of acyclovir (Zovirax) in intravenous-to-oral switch therapy?

Updated: Jul 30, 2018
  • Author: Shirin A Mazumder, MD, FIDSA; Chief Editor: Pranatharthi Haran Chandrasekar, MBBS, MD  more...
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Carcao and colleagues noted that immunocompromised children are at risk for disseminated varicella infections and that standard treatment involves hospitalization and intravenous acyclovir for 7-10 days. Carcao et al undertook a pilot study to assess the safety and efficacy of an alternative approach that involved a combination of intravenous followed by oral acyclovir in a cohort of immunocompromised children. Specifically, the cohort consisted of 26 immunocompromised children aged 1.5-12.7 years (mean age, 6.3 y). [49]

Therapy was commenced with intravenous acyclovir (1500 mg/m2/d in 3 divided doses). Concurrent treatment included holding or reducing immunosuppressive therapy (by 50%) and administering varicella-zoster immunoglobulin in 11 (69%) of 16 patients in whom exposure to chickenpox was recognized. Patients were eligible to switch to oral therapy after receiving a minimum of 48 hours of intravenous acyclovir therapy, provided they were afebrile, had no new lesions for 24 hours, had no internal organ involvement, and were able to tolerate oral medications. [49]

Patients were observed in the hospital for another 24 hours and were then discharged provided they remained well. Oral acyclovir was continued for a total of 7-10 days (intravenous plus oral). Carcao et al found that 25 of the 26 patients were successfully switched from intravenous to oral administration after 4.1 (mean) ± 1.2 days (standard deviation) (range, 2.3-6 d). Children had fever for a mean of 2 ± 1.6 days (range, 0-5 d) and developed new lesions for 2.9 ± 0.7 days (range, 2-4 d). [49]

Disease resolved in all 25 patients who switched to oral therapy, and no patient required resumption of intravenous therapy. Carcao and associates concluded that the sequential use of intravenous acyclovir followed by oral acyclovir is feasible in the treatment of varicella infection in immunocompromised children and results in a reduced duration of intravenous therapy and hospitalization. [49]

Acyclovir (Zovirax) inhibits activity of both HSV-1 and HSV-2. It has affinity for viral thymidine kinase and, once phosphorylated, causes DNA chain termination when acted on by DNA polymerase. Patients experience less pain and faster resolution of cutaneous lesions when used within 48 h of rash onset. It may also prevent recurrent outbreaks. Early initiation of therapy is imperative. Adult dosing is 600-800 mg PO 5 times/d for 7 d or 10 mg/kg/dose IV q8h; initiate treatment immediately upon onset of symptoms of recurrent episodes. In immunocompromised adults, dosing is 800 mg PO q4h (5 times/d) for 7-10 d. In children, dosing is (1) 250-600 mg/m2/dose PO 4-5 times/d for 7-10 d or (2) 1500 mg/m2/d IV divided q8h or 10 mg/kg/dose IV q8h for 7 d.

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