Oral Genital herpes, Herpes simplex infections of skin and mucous membranes
Adult: Immunocompetent patients: 500 mg bid for 3-5 days for recurrent episodes or for up to 10 days for initial episodes. Immunocompromised patients: 1,000 mg bid for at least 5 days for recurrent episodes or for up to 10 days for initial episodes. Treatment duration is based on severity of clinical condition and immunological status. Child: ≥12 years Same as adult dose.
Adult: Immunocompetent patients: 1,000 mg tid for 7 days. Immunocompromised patients: 1,000 mg tid for at least 7 days and for 2 days after crusting of lesions.
Oral Herpes labialis
Adult: 2,000 mg 12 hourly for 1 day. Child: ≥12 years Same as adult dose.
Oral Prophylaxis of cytomegaloviral infections in immunocompromised patients
Adult: Patient following solid organ transplantation: 2,000 mg 4 times daily, usually for 90 days according to patient response. Child: ≥12 years Same as adult dose.
Oral Suppression of recurrent herpes simplex
Adult: Immunocompetent patients: 500 mg once daily. Patient with ≥10 relapses a year: 250 mg bid. Immunocompromised patients: 500 mg bid. Re-evaluate treatment after 6-12 months of therapy. Child: ≥12 years Same as adult dose.
Renal Impairment
Herpes zoster (shingles); Herpes zoster ophthalmicus: Patient on haemodialysis: Lowest recommended dose after the dialysis session.
CrCl (mL/min)
Dosage
30-49
Immunocompetent and immunocompromised patients: 1,000 mg bid.
10-29
Immunocompetent and immunocompromised patients: 1,000 mg once daily.
<10
Immunocompetent and immunocompromised patients: 500 mg once daily.
Herpes simplex infections of skin and mucous membranes; Genital herpes: Patient on haemodialysis: Lowest recommended dose after the dialysis session.
Immunocompetent patients: 500 mg once daily. Immunocompromised patients: 1,000 mg once daily.
Herpes labialis:
Patient on haemodialysis: Lowest recommended dose after the dialysis session.
CrCl (mL/min)
Dosage
30-49
1,000 mg 12 hourly for 1 day.
10-29
500 mg 12 hourly for 1 day.
<10
500 mg as a single dose.
Suppression of recurrent herpes simplex:
CrCl (mL/min)
Dosage
≥30
Immunocompetent patients: 500 mg once daily; Patient with ≥10 relapses a year: 250 mg bid; Immunocompromised patients: 500 mg bid.
<30
Immunocompetent patients: 250 mg once daily. Immunocompromised patients: 500 mg once daily.
Prophylaxis of cytomegaloviral infections in immunocompromised patients:
Patient on haemodialysis: 1,500 mg once daily.
CrCl (mL/min)
Dosage
50-74
1,500 mg 4 times daily.
25-49
1,500 mg tid.
10-24
1,500 mg bid.
<10
1,500 mg once daily.
Administration
May be taken with or without food. May be taken w/ meals to reduce GI discomfort.
Contraindications
Hypersensitivity.
Special Precautions
Patients inadequately hydrated or at risk of dehydration; immunocompromised patients. Concomitant use with nephrotoxic agents. Renal and hepatic impairment. Elderly. Pregnancy and lactation.
Adverse Reactions
Significant: Acute renal failure, CNS effects (e.g. agitation, hallucination, confusion, delirium, seizures, encephalopathy). Blood and lymphatic system disorders: Thrombocytopenia, leucopenia. Gastrointestinal disorders: Nausea, abdominal pain, vomiting, diarrhoea. General disorders and admin site conditions: Fatigue, ataxia, fever. Immune system disorders: Urticaria. Rarely, anaphylaxis, angioedema. Investigations: Elevated liver enzymes. Metabolism and nutrition disorders: Dehydration. Musculoskeletal and connective tissue disorders: Arthralgia. Nervous system disorders: Headache, dizziness, decreased consciousness, tremor. Psychiatric disorders: Dysarthria. Renal and urinary disorders: Renal pain, haematuria. Reproductive system and breast disorders: Dysmenorrhoea. Respiratory, thoracic and mediastinal disorders: Nasopharyngitis, dyspnoea. Skin and subcutaneous tissue disorders: Rashes, pruritus, photosensitivity. Potentially Fatal: In patients with advanced HIV infection receiving high doses (8,000 mg daily) for prolonged period: Thrombotic thrombocytopenic purpura, haemolytic uremic syndrome.
This drug does not reduce your risk of passing genital herpes through sexual contact, if symptoms are present, avoid sexual intercourse or use safer sex practices.
Monitoring Parameters
Monitor LFTs, CBC, BUN, serum creatinine and urinalysis regularly during treatment. Assess for signs of CNS changes.
Overdosage
Symptoms: Acute renal failure, nausea, vomiting, confusion, agitation, hallucinations, decreased consciousness, and coma. Management: May consider haemodialysis to enhance removal of aciclovir from the blood.
Drug Interactions
Increased risk of renal impairment with nephrotoxic drugs (e.g. aminoglycosides, organoplatinum compounds, iodinated contrast media, methotrexate, pentamidine, foscarnet, ciclosporin, tacrolimus). Probenecid and cimetidine may reduce renal clearance of aciclovir.
Action
Description: Mechanism of Action: Valaciclovir is rapidly and almost completely converted via hepatic and intestinal metabolism to aciclovir, then converted to aciclovir monophosphate by virus-specific thymidine kinase, then further converted to aciclovir triphosphate by other cellular enzymes. Aciclovir triphosphate inhibits DNA synthesis and viral replication by competing with deoxyguanosine triphosphate for viral DNA polymerase and being incorporated into viral DNA. Pharmacokinetics: Absorption: Rapidly absorbed from the gastrointestinal tract. Bioavailability: Approx 54% (aciclovir). Time to peak plasma concentration: Approx 1-2 hours. Distribution: Widely distributed into body organs, muscle, uterus, vagina and CSF. Enters breast milk (aciclovir). Plasma protein binding: Approx 14-18%. Metabolism: Converted to aciclovir and L-valine via first-pass intestinal and/or hepatic metabolism. Aciclovir is converted to a small extent by aldehyde oxidase and by alcohol and aldehyde dehydroxegenase to its inactive metabolites. Excretion: Mainly via urine (89% as aciclovir; <1% as unchanged drug); faeces (46% as non-absorbed drug). Elimination half-life: Approx 30 minutes (valaciclovir); 2.5-3.3 hours (aciclovir). End-stage renal disease: 14-20 hours (aciclovir); During hemodialysis: 4 hours.
Chemical Structure
Valaciclovir Source: National Center for Biotechnology Information. PubChem Database. Valacyclovir, CID=135398742, https://pubchem.ncbi.nlm.nih.gov/compound/Valacyclovir (accessed on Jan. 23, 2020)
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 17/06/2019.Anon. Valacyclovir. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 17/06/2019.Buckingham R (ed). Valaciclovir Hydrochloride. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 17/06/2019.Valaciclovir 250 mg Film-Coated Tablets (Torrent Pharma UK Ltd.). MHRA. https://products.mhra.gov.uk/. Accessed 17/06/2019.Valacyclovir Hydrochloride Tablet, Film Coated (Actavis Pharma, Inc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 17/06/2019.
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