Child: 2-<18 years Immunocompetent patients: 20 mg/kg (Max: 1,000 mg) tid for 5 days. Start treatment within 24 hours of the onset of rash. Treatment recommendations may vary between countries (refer to latest local guidelines).
Oral Herpes zoster
Adult: Immunocompetent patients: 1,000 mg tid for 7 days. Immunocompromised patients: 1,000 mg tid for at least 7 days and continue for further 2 days after crusting of lesions. Start treatment at the earliest sign or symptom (ideally within 48-72 hours). Treatment recommendations may vary between countries (refer to latest local guidelines).
Oral Herpes simplex infections of skin and mucous membranes
Adult: Immunocompetent patients: 500 mg bid for 3-5 days for recurrent episodes or up to 10 days for initial episodes. Immunocompromised patients: 1,000 mg bid for at least 5 days for recurrent episodes or up to 10 days for initial episodes. Start treatment as early as possible. Dosage and treatment recommendations may vary between countries (refer to latest local guidelines). Child: ≥12 years Immunocompetent patients: 500 mg bid for 3-5 days for recurrent episodes or up to 10 days for initial episodes. Start treatment as early as possible. Treatment recommendations may vary between countries (refer to latest local guidelines).
Oral Prophylaxis of cytomegalovirus infection in organ transplantation
Adult: In solid organ transplant recipients: 2,000 mg 4 times daily. Prophylaxis should be started as early as possible post-transplant. Treatment duration is usually 90 days. Child: ≥12 years Same as adult dose.
Oral Herpes labialis
Adult: Immunocompetent patients: 2,000 mg 12 hourly for 1 day. Child: ≥12 years Same as adult dose.
Oral Suppression of recurrent herpes simplex
Adult: Immunocompetent patients: 500 mg once daily; for patients with very frequent recurrences (e.g. ≥10 recurrences per year), 250 mg bid may be given. Immunocompromised patients: 500 mg bid. Re-evaluate treatment after 6-12 months. Dosage and treatment recommendations may vary between countries (refer to latest local guidelines). Child: ≥12 years Immunocompetent patients: 500 mg once daily; for patients with very frequent recurrences (e.g. ≥10 recurrences per year), 250 mg bid may be given. Re-evaluate treatment after 6-12 months. Treatment recommendations may vary between countries (refer to latest local guidelines).
What are the brands available for Valaciclovir in Hong Kong?
Herpes zoster:
Patients on intermittent haemodialysis: Administer dose after the dialysis session on dialysis days.
CrCl (mL/min)
Dosage
<10
Immunocompetent and immunocompromised patients: 500 mg once daily.
10-29
Immunocompetent and immunocompromised patients: 1,000 mg once daily.
30-49
Immunocompetent and immunocompromised patients: 1,000 mg bid.
Herpes simplex infections of skin and mucous membranes:
Patients on intermittent haemodialysis: Administer dose after the dialysis session on dialysis days.
CrCl (mL/min)
Dosage
<30
Immunocompetent patients: 500 mg once daily. Immunocompromised patients: 1,000 mg once daily.
Dosage recommendations may vary between countries (refer to latest local guidelines).
Suppression of recurrent herpes simplex:
Patients on intermittent haemodialysis: Administer dose after the dialysis session on dialysis days.
CrCl (mL/min)
Dosage
<30
Immunocompetent patients: 250 mg once daily. Immunocompromised patients: 500 mg once daily.
≥30
Immunocompetent patients: 500 mg once daily; for patients with very frequent recurrences (e.g. ≥10 recurrences per year), 250 mg bid may be given. Immunocompromised patients: 500 mg bid.
Dosage recommendations may vary between countries (refer to latest local guidelines).
Herpes labialis:
Patients on intermittent haemodialysis: Administer dose after the dialysis session on dialysis days.
CrCl (mL/min)
Dosage
<10
Immunocompetent patients: 500 mg as a single dose.
10-29
Immunocompetent patients: 500 mg 12 hourly for 1 day.
30-49
Immunocompetent patients: 1,000 mg 12 hourly for 1 day.
Prophylaxis of cytomegalovirus infection in organ transplantation:
Patient on dialysis: 1,500 mg once daily. Dose must be given after dialysis.
CrCl (mL/min)
Dosage
<10
1,500 mg once daily.
10-24
1,500 mg bid.
25-49
1,500 mg tid.
50-74
1,500 mg 4 times daily.
Administration
Valaciclovir May be taken with or without food. May be taken w/ meals to reduce GI discomfort.
Contraindications
Hypersensitivity to valaciclovir or aciclovir.
Special Precautions
Patient who are at risk of dehydration. Renal and hepatic impairment. Children and elderly. Pregnancy and lactation.
Adverse Reactions
Significant: Neurological reactions (e.g. agitation, confusion, hallucinations, dysarthria, impaired consciousness, tremor, seizures); acute kidney injury or acute renal failure. Blood and lymphatic system disorders: Leucopenia (mainly in immunocompromised patients), thrombocytopenia. Gastrointestinal disorders: Nausea, vomiting, diarrhoea, abdominal discomfort. Investigations: Increased LFTs (reversible). Nervous system disorders: Headache, dizziness. Respiratory, thoracic and mediastinal disorders: Dyspnoea, nasopharyngitis. Skin and subcutaneous tissue disorders: Rash, photosensitivity, pruritus, urticaria. Potentially Fatal: Drug reaction with eosinophilia and systemic symptoms (DRESS); thrombotic thrombocytopenic purpura or haemolytic uraemic syndrome (particularly in patients with advanced HIV disease treated for prolonged periods).
Ensure adequate fluid intake. This drug does not cure or eliminate the risk of transmission of genital herpes, avoid sexual intercourse when symptoms are present or use safer sex practices (particularly use of condoms).
Monitoring Parameters
Monitor urinalysis, BUN, serum creatinine, CBC, liver enzymes, and hydration status. Assess for signs and symptoms of neurotoxicity and DRESS.
Overdosage
Symptoms: Acute renal failure, confusion, hallucinations, nausea, vomiting, agitation, decreased consciousness and coma. Management: May consider haemodialysis to enhance removal of aciclovir from the blood.
Drug Interactions
Probenecid and cimetidine reduce the renal clearance and increase plasma concentration of aciclovir (active metabolite). Increased risk of renal impairment with nephrotoxic drugs (e.g. aminoglycosides, methotrexate, pentamidine, foscarnet, ciclosporin, tacrolimus, organoplatinum compounds, iodinated contrast media). Concomitant use with mycophenolic acid may increase the serum concentrations of aciclovir and the inactive metabolite of mycophenolic acid.
Action
Description: Mechanism of Action: Valaciclovir is a prodrug of aciclovir. It is rapidly and almost completely converted to aciclovir and subsequently to aciclovir triphosphate (active metabolite). Aciclovir triphosphate prevents viral DNA synthesis and replication by competitively inhibiting viral DNA polymerase and by being incorporated into the viral DNA chain. Synonym(s): Valacyclovir. Pharmacokinetics: Absorption: Rapidly absorbed from the gastrointestinal tract. Bioavailability: Approx 54% (aciclovir). Time to peak plasma concentration: 1-2 hours (aciclovir). Distribution: Widely distributed into the body, including the brain, lungs, liver, kidney, spleen, uterus, muscle, vagina, and CSF (aciclovir). Enters breast milk (aciclovir). Plasma protein binding: 13.5-17.9% (valaciclovir); 9-33% (aciclovir). Metabolism: Rapidly and almost completely converted to L-valine and aciclovir via first-pass intestinal or hepatic metabolism; aciclovir is subsequently converted to aciclovir monophosphate, diphosphate, and triphosphate. Excretion: Via urine (89% as aciclovir, <1% as unchanged drug). Elimination half-life: Approx 30 minutes (valaciclovir); 2.5-3.3 hours (aciclovir).
Chemical Structure
Valaciclovir Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 135398742, Valacyclovir. https://pubchem.ncbi.nlm.nih.gov/compound/Valacyclovir. Accessed Sept. 30, 2024.
J05AB11 - valaciclovir ; Belongs to the class of nucleosides and nucleotides excluding reverse transcriptase inhibitors. Used in the systemic treatment of viral infections.
References
Anon. Valacyclovir. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 09/05/2024.Brayfield A, Cadart C (eds). Valaciclovir Hydrochloride. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 19/08/2024.Joint Formulary Committee. Valaciclovir. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 09/05/2024.Paediatric Formulary Committee. Valaciclovir. BNF for Children [online]. London. BMJ Group, Pharmaceutical Press, and RCPCH Publications. https://www.medicinescomplete.com. Accessed 09/05/2024.Valaciclovir [Valacyclovir]. UpToDate Lexidrug, Lexi-Drugs Multinational Online. Waltham, MA. UpToDate, Inc. https://online.lexi.com. Accessed 09/05/2024.Valacyclovir Hydrochloride Tablet, Film Coated (Aurobindo Pharma Limited). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 19/08/2024.Valtrex 250 mg Film-coated Tablets (The Welcome Foundation Ltd, Trading as GlaxoSmithKline UK). MHRA. https://products.mhra.gov.uk. Accessed 09/05/2024.Valtrex Film-coated Tablets (GlaxoSmithKline Pharmaceutical Sdn. Bhd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 09/05/2024.Viatris Ltd. Vaclovir 500 mg & 1,000 mg, Film Coated Tablet data sheet 11 May 2023. Medsafe. http://www.medsafe.govt.nz. Accessed 09/05/2024.
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