Trade Names:Valtrex- Tablets 500 mg- Tablets 1 g
Converted to acyclovir, which then inhibits viral DNA replication by interfering with viral DNA polymerase.
Rapidly absorbed from the GI tract. Bioavailability is about 55%.
C max ranges from 0.83 to 5.65 mcg/mL, depending on the dose.
Protein binding ranges from 14% to 18%.
Converted to acyclovir and/or L-valine by first-pass intestinal or hepatic metabolism.
About 46% is recovered in urine. About 47% is recovered in feces. Elimination half-life is approximately 2.5 to 3.3 h.
Dose reduction is recommended.Hepatic Function Impairment
Dose modification is not recommended in patients with cirrhosis.Elderly
Dose modification may be necessary in elderly patients with reduced renal function.Children
C max approximately 4.2 mcg/mL in children 1 month to younger than 12 yr of age.
Treatment of cold sores (herpes labialis); treatment of initial and recurrent episodes of genital herpes in immunocompetent patients; suppression of recurrent episodes of genital herpes in immunocompetent and HIV-infected patients; reduction of transmission of genital herpes in immunocompetent patients; treatment of herpes zoster (shingles) in immunocompetent adults.Children
Treatment of cold sores in children 12 yr of age and older; treatment of chickenpox in immunocompetent patients 2 to 18 yr of age.
Clinically important hypersensitivity reaction (eg, anaphylaxis) to valacyclovir, acyclovir, or any component of the product.
PO 20 mg/kg administered 3 times daily for 5 days (max, 1 g 3 times daily). Initiate therapy at earliest sign or symptom.Genital HerpesAdults HIV-infected patients
PO 500 mg twice daily for suppressive therapy in HIV-infected patients with CD4 cell count of at least 100 cells/mm 3 (efficacy beyond 6 mo of therapy has not been established).Initial episodes
PO 1 g twice daily for 10 days (initiate therapy within 48 h of onset of signs and symptoms).Recurrent episodes
PO 500 mg twice daily for 3 days (initiate therapy at first sign or symptom).Reduction of transmission
PO 500 mg once daily for the source partner in patients with a history of 9 or fewer recurrences per year.Suppressive therapy
PO 1 g once daily. In patients with a history of 9 or fewer recurrences per year, 500 mg/day may be administered.Hemodialysis
PO Administer the recommended dose after hemodialysisHerpes LabialisAdults
PO 2 g twice daily for 1 day approximately 12 h apart, initiated at earliest symptoms of cold sore (eg, tingling, burning, itching).Children 12 yr of age and older
PO 2 g twice daily for 1 day taken 12 h apart. Initiate therapy at earliest symptoms of a cold sore.Herpes ZosterAdults
PO 1 g 3 times daily for 7 days (initiate therapy within 48 h of onset of rash or at earliest sign or symptom).
Store at controlled room temperature (59° to 77°F).
Increased acyclovir serum concentrations.
None well documented.
Hypertension, tachycardia (postmarketing).
Headache (38%); fatigue (8%); depression (7%); dizziness, pyrexia (4%); aggressive behavior, agitation, ataxia, coma, confusion, decreased consciousness, dysarthria, encephalopathy, mania, psychosis (including audio and visual hallucinations), seizures, tremors (postmarketing).
Rash (8%); alopecia, erythema multiforme, rashes (including photosensitivity) (postmarketing).
Nasopharyngitis (16%); visual abnormalities (postmarketing).
Nausea (15%); abdominal pain (11%); vomiting (6%); diarrhea (5%).
Dysmenorrhea (8%); renal failure (postmarketing).
Aplastic anemia, hemolytic uremic syndrome, leukocytoclastic vasculitis, thrombocytopenia, thrombocytopenic purpura (postmarketing).
Decreased neutrophil counts (18%); increased AST (16%); increased ALT (14%); elevated alkaline phosphatase (4%); decreased platelet counts (3%); decreased hemoglobin, increased serum creatinine, leukopenia (1%).
Arthralgia (6%); herpes simplex (2%); acute hypersensitivity reactions (including anaphylaxis, angioedema, dyspnea, pruritus, rash, and urticaria), facial edema (postmarketing).
Category B .
Undetermined (acyclovir is excreted in breast milk).
Safety and efficacy not established in children younger than 12 yr of age with cold sores; younger than 18 yr of age with genital herpes or herpes zoster; younger than 2 yr of age with chickenpox.
Dosage reduction may be necessary, depending on underlying renal status.
Dosage reduction is recommended; exercise caution when giving valacyclovir to patients with renal function impairment or those receiving potentially nephrotoxic drugs.
Has occurred in elderly patients; patients with underlying renal disease who received higher than recommended doses for their level of renal function; patients receiving other nephrotoxic drugs; and patients without adequate hydration.
CNS reactions, including agitation, confusion, delirium, encephalopathy, hallucinations, and seizures, have been reported in elderly patients with and without reduced renal function and in patients with underlying renal disease who received higher than recommended doses for their level of renal function.
Safety and efficacy not established in immunocompromised patients other than for the suppression of genital herpes in HIV-infected patients.
May occur and has resulted in death in patients with advanced HIV disease and also in allogenic bone marrow and renal transplant recipients receiving valacyclovir 8 g/day.
Acute renal failure, anuria.
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