Drug information of Valacyclovir
Valacyclovir is an antiviral drug. It slows the growth and spread of the herpes virus so that the body can fight off the infection. It will not cure herpes, but it can lessen the symptoms of the infection. Valacyclovir is used to treat infections caused by herpes viruses in adults and children. Illnesses caused by herpes viruses include genital herpes, cold sores, shingles, and chickenpox. Valacyclovir is used to treat cold sores in children who are at least 12 years old, and to treat chickenpox in children who are at least 2 years old.
Mechanism of effect
Valacyclovir is phosphorylated by viral thymidine kinase to acyclovir triphosphate (the active metabolite) which then inhibits herpes viral DNA replication by competitive inhibition of viral DNA polymerase, and by incorporation into and termination of the growing viral DNA chain.
Valacyclovir is an antiviral drug
After oral administration, Valacyclovir hydrochloride is rapidly absorbed from the gastrointestinal tract and nearly completely converted to acyclovir and L-valine by first-pass intestinal and/or hepatic metabolism. The binding of Valacyclovir to human plasma proteins ranges from 13.5% to 17.9%. 46% and 47% of administered Valacyclovir was recovered in urine and feces, respectively. The plasma elimination half-life of acyclovir typically averaged 2.5 to 3.3 hours in all studies of Valacyclovir hydrochloride in volunteers with normal renal function.
Usual Adult Dose for Herpes Simplex Labialis 2 g orally every 12 hours for a total of 2 doses (4 g) Therapy should be started at the earliest sign of a cold sore (such as tingling, burning, or itching). Usual Pediatric Dose for Herpes Simplex Labialis 12 years or older: 2 g orally every 12 hours for a total of 2 doses (4 g)
Drug contraindicationshypersensitivity to drug or its components.
Side effectsTachycardia , Diarrhea , Hypertension , confusion , agitation , ataxia , Anaphylactic reaction , renal failure , coma , hepatitis , hallucinations , Facial edema , Visual abnormalities
InteractionsMeglumine Compound , Diatrizoate (Amidotrizoic acid) , Foscarnet , Zoster Vaccines , Ioxaglate , Iothalamate Meglumine
1- Thrombotic Thrombocytopenic Purpura/Hemolytic Uremic Syndrome (TTP/HUS) in some cases resulting in death, has occurred in patients with advanced HIV disease and also in allogeneic bone marrow transplant and renal transplant recipients participating in clinical trials of Valacyclovir hydrochloride at doses of 8 grams per day. Treatment with Valacyclovir hydrochloride should be stopped immediately if clinical signs, symptoms, and laboratory abnormalities consistent with TTP/HUS occur. 2- Cases of acute renal failure have been reported in: Elderly patients with or without reduced renal function, renal disease, Patients receiving other nephrotoxic drugs, Patients without adequate hydration.
Points of recommendation
1- Patients should be advised to initiate treatment at the earliest symptom of a cold sore (e.g., tingling, itching, or burning) 2- Patients should be informed that Valacyclovir hydrochloride is not a cure for genital herpes. 3- Patients should be advised to initiate treatment as soon as possible after a diagnosis of herpes zoster. 4- Patients should be advised to initiate treatment at the earliest sign or symptom of chickenpox. 5- Do not have sexual contact with your partner when you have any symptom or outbreak of genital herpes. Use a condom made of latex or polyurethane whenever you have sexual contact.