Patient at risk of dehydration. Renal impairment. Pregnancy and lactation. Patient Counselling Avoid sexual intercourse when symptoms of genital herpes are present. Monitoring Parameters Monitor renal, hepatic and haematological functions.
Lactation: Drug excreted in breast milk; use with caution
FDA has not yet classified the drug into a specified pregnancy category.
Mode of Action
Valaciclovir is the L-valine ester of aciclovir. A prodrug, it is rapidly converted to aciclovir by intestinal and hepatic metabolism. Aciclovir inhibits DNA synthesis and viral replication and has antiviral activity against herpes simplex virus types 1 (HSV-1) and 2 (HSV-2) and varicella-zoster virus.
Interaction
Increased risk of renal failure w/ nephrotoxic drugs (e.g. aminoglycosides, organoplatinum compounds, iodinated contrast media, methotrexate, pentamidine, foscarnet, ciclosporin, tacrolimus). Probenecid and cimetidine may increase peak plasma concentrations and AUC of aciclovir.
Pregnancy Category Note
Pregnancy
Clinical data over several decades with valacyclovir and its metabolite, acyclovir, in pregnant women, have not identified a drug associated risk of major birth defects; there are insufficient data on use of valacyclovir regarding miscarriage or adverse maternal or fetal outcomes; there are risks to fetus associated with untreated herpes simplex during pregnancy
Risk of neonatal HSV infection varies from 30% to 50% for genital HSV acquired in late pregnancy (third trimester), whereas with HSV acquisition in early pregnancy, risk of neonatal infection is about 1%; a primary herpes occurrence during first trimester of pregnancy has been associated with neonatal chorioretinitis, microcephaly, and, in rare cases, skin lesions; in very rare cases, transplacental transmission can occur resulting in congenital infection, including microcephaly, hepatosplenomegaly, intrauterine growth restriction, and stillbirth
Co-infection with HSV increases risk of perinatal HIV transmission in women who had a clinical diagnosis of genital herpes during pregnancy
Animal data
In animal reproduction studies, no evidence of adverse developmental outcomes was observed with valacyclovir when administered to pregnant rats and rabbits at system exposures (AUC) 4 (rats) and 7 (rabbits) times human exposure at maximum recommended human dose (MRHD)
Lactation
Although there is no information on presence of drug in human milk, its metabolite, acyclovir, is present in human milk following oral administration of drug; based on published data, a 500-mg maternal dose twice daily would provide a breastfed child with an oral acyclovir dosage of approximately 0.6 mg/kg/day; there is no data on effects of drug on breastfed child or on milk production
Consider developmental and health benefits of breastfeeding along with mother?s clinical need for therapy and any potential adverse effects on breastfed child from drug or from underlying maternal condition
Adult Dose
Oral
Herpes zoster (shingles)
Adult: 1 g tid for 7 days. Immunocompromised patients: Continue treatment for a further 2 days after crusting of lesions.
Herpes simplex infections of skin and mucous membranes; Genital herpes
Adult: 500 mg bid for 3-5 days for recurrent episodes or up to 10 days for initial episodes. Immunocompromised patients: 1 g bid for at least 5 days for recurrent episodes or up to 10 days for initial episodes.
Prophylaxis of cytomegaloviral infections in immunocompromised patients
Adult: 2 g 4 times daily, begin as soon as possible post-transplant and usually continued for 90 days.
Herpes labialis
Adult: 2 g 12 hrly for 1 day.
Suppression of recurrent herpes simplex
Adult: 500 mg daily as a single or in 2 divided doses. Immunocompromised patients: 500 mg bid. Treatment is re-evaluated after 6-12 mth of therapy.
Child Dose
Herpes simplex infections of skin and mucous membranes; Genital herpes
Child: >12 yr: 500 mg bid for 3-5 days for recurrent episodes or up to 10 days for initial episodes. Immunocompromised patients: 1 g bid for at least 5 days for recurrent episodes or up to 10 days for initial episodes.
Prophylaxis of cytomegaloviral infections in immunocompromised patients
Child: >12 yr: 2 g 4 times daily, begin as soon as possible post-transplant and usually continued for 90 days.
Herpes labialis
Child: >12 yr: 2 g 12 hrly for 1 day.
Suppression of recurrent herpes simplex
Adult:
Child: >12 yr: 500 mg daily as a single or in 2 divided doses. Immunocompromised patients: 500 mg bid. Treatment is re-evaluated after 6-12 mth of therapy.
Chickenpox
<2 years: Safety and efficacy not established
>2 years: 20 mg/kg PO q8hr for 5 days; not to exceed 1 g PO q8hr
Renal Dose
Herpes labialis
CrCl 30-49 mL/min: 1 g PO q12hr for 1 day
CrCl 10-29 mL/min: 500 mg PO q12hr for 1 day
CrCl <10 mL/min: 500 mg PO once
Herpes zoster
CrCl 30-49 mL/min: 1 g PO q12hr
CrCl 10-29 mL/min: 1 g/day PO
CrCl <10 mL/min: 500 mg/day PO
Genital herpes (initial episode)
CrCl 10-29 mL/min: 1 g/day PO
CrCl <10 mL/min: 500 mg/day PO qDay
Genital herpes (recurrent episodes)(suppressive therapy, immunocompetent patients)
CrCl <29 mL/min: 500 mg/day PO
Administration
May be taken with or without food. May be taken w/ meals to reduce GI discomfort.
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