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Indications and Dosage
Oral
Chronic hepatitis B Adult: As treatment in cases with evidence of active viral replication and either evidence of persistent elevations in serum aminotransferases (ALT or AST) or histologically active disease: 10 mg once daily.
Child: ≥12 years Same as adult dose. |
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Renal Impairment
Haemodialysis patients: 10 mg every 7 days after dialysis.
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Contraindications
Hypersensitivity. Lactation. Concurrent use with tenofovir (e.g. tenofovir disoproxil fumarate or tenofovir alafenamide) or any tenofovir-containing product.
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Special Precautions
Patient with hepatomegaly or other risk factors for liver disease. Renal impairment. Children.
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Adverse Reactions
Significant: Nephrotoxicity (particularly when used long-term in patients at risk of or have underlying renal dysfunction); HIV resistance (in patients with unrecognised or untreated HIV infection); severe acute exacerbations of hepatitis (upon discontinuation of treatment).
Gastrointestinal disorders: Nausea, abdominal pain, flatulence, dyspepsia, vomiting, diarrhoea, pancreatitis. General disorders and administration site conditions: Asthenia. Investigations: Increased serum creatinine. Metabolism and nutrition disorders: Hypophosphataemia. Musculoskeletal and connective tissue disorders: Myopathy, osteomalacia. Nervous system disorders: Headache. Potentially Fatal: Lactic acidosis, severe hepatomegaly with steatosis. |
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Monitoring Parameters
Determine HIV status prior to treatment. Monitor renal function during treatment. Perform HBV DNA test every 3 months until undetectable and then every 3-6 months thereafter. Assess for signs and symptoms of lactic acidosis regularly. Closely monitor hepatic function during treatment and after discontinuation of therapy.
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Overdosage
Symptoms: Gastrointestinal disturbances. Management: Supportive treatment. May perform haemodialysis.
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Drug Interactions
Increased risk of nephrotoxicity with other nephrotoxic drugs (e.g. aminoglycosides, ciclosporin, tacrolimus, vancomycin, certain NSAIDs). Increased serum concentration with other drugs that reduce renal function or compete for active tubular secretion.
Potentially Fatal: May diminish the therapeutic effect of tenofovir or tenofovir-containing products. |
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Action
Description:
Mechanism of Action: Adefovir, an acyclic nucleotide analogue, is an antiviral agent that is active against human HBV. It is phosphorylated to adefovir diphosphate, which subsequently competes with the natural substrate deoxyadenosine triphosphate and causes DNA chain termination after its incorporation into the viral DNA. This results in the inhibition of HBV DNA polymerase (reverse transcriptase) and viral replication. Pharmacokinetics: Absorption: Bioavailability: 59%. Time to peak plasma concentration: Approx 0.6-4 hours. Distribution: Widely distributed to body tissues, particularly into the kidneys, liver and intestines. Volume of distribution: 0.35-0.39 L/kg. Plasma protein binding: ≤4%. Metabolism: Adefovir dipivoxil is rapidly converted into adefovir via diester hydrolysis and subsequently forms adefovir diphosphate (active metabolite) via phosphorylation by cellular enzymes. Excretion: Via urine (45% as active metabolite). Terminal elimination half-life: Approx 7 hours. |
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Chemical Structure
 Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 60172, Adefovir. https://pubchem.ncbi.nlm.nih.gov/compound/Adefovir. Accessed Oct. 24, 2023. |
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Storage
Store below 25°C. Protect from heat and moisture.
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MIMS Class
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ATC Classification
J05AF08 - adefovir dipivoxil ; Belongs to the class of nucleoside and nucleotide reverse transcriptase inhibitors. Used in the systemic treatment of viral infections.
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References
Adefovir Dipivoxil Tablet (Sigmapharm Laboratories, LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 30/06/2023. Anon. Adefovir. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 30/06/2023. Anon. Adefovir. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 30/06/2023. Buckingham R (ed). Adefovir. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 30/06/2023. Hepsera Tablets (Gilead Sciences, Inc.). U.S. FDA. https://www.fda.gov. Accessed 30/06/2023. Joint Formulary Committee. Adefovir Dipivoxil. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 30/06/2023.
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