#valacyclovir hypochloride

Brand Name: Valtrex

Generic Available

Common Dosage Forms:

Tablets: 500 mg, 1000 mg

FDA Indications/Dosages:

For the treatment of genital herpes: 1 gram twice daily for 10 days.

For the treatment of recurrent episodes of genital herpes: 500 mg twice daily for 3 days.

Chronic suppressive therapy for recurrent genital herpes: From 500 mg to 1 gram daily depending on the number of recurrences per year.

For the treatment of herpes zoster (shingles): 1 gram three times daily for 7 days. Therapy should be initiated at the earliest sign of disease.

For the treatment of cold sores (herpes labialis) in patients over the age of 12 years: 2 grams given twice daily for 1 day starting at the earliest sign of a cold sore.

Patients with acute or chronic renal impairment (Ccr <29 mL/min): Double the interval between dose, i.e., if the normal dose calls for twice a day dosing, give medication once a day.

Pharmacology/Pharmacokinetics: Valacyclovir is rapidly converted to acyclovir by first-pass intestinal and/or hepatic metabolism. Acyclovir is a synthetic acyclic purine nucleotide which in vitro inhibits herpes simplex types 1 and 2, varicella-zoster, Epstein-Barr, and cytomegalovirus. In vitro, the inhibitory activity of acyclovir if highly selective for herpes simplex virus (HSV). Acyclovir is preferentially taken up and converted to the active triphosphate form by HSV infected cells which then interferes with the HSV DNA polymerase and inhibits viral DNA replication. In vitro, as the acyclovir triphosphate is incorporated into the growing chains of DNA by viral and cellular DNA polymerase, the DNA chain is terminated. The relationship between in vitro susceptibility of HSV to acyclovir and clinical response has not been established. Half-life after oral administration ranges between 2.5 and 3.3 hours. Steady state plasma levels are reached in 2 days.

Drug Interactions: Probenecid may decrease elimination.

Contraindications/Precautions: Valacyclovir is contraindicated in patients with known hypersensitivity to any component of its formulation. Reduce dosage in patients who have renal impairment. Precipitation of acyclovir in renal tubules may occur in dehydrated patients. Patients should be advised that even while on therapy, viral mutation of herpes simplex can occur, and care should be taken to avoid transmission of the virus during active phases of the disease. Pregnancy Category B.

Adverse Effects: Nausea, vomiting, headache, and abdominal pain.

Patient Consultation:

Avoid sexual intercourse when used for genital herpes and when visible lesions are present. Valacyclovir does not eliminate the latent virus and is not a cure.

Notify a physician if frequency and severity of recurrences do not improve or patients becomes pregnant or intends to become pregnant.

Patients should drink plenty of fluids during therapy.

Store in a cool, dry place away from sunlight and children.

If a dose is missed, take it as soon as possible. If it is closer to the time of your next dose than the dose you missed, skip the missed dose and return to your dosing schedule. Do not double doses.