Adult: 300 mg once daily. Child: ≥2 years weighing >10 kg: 8 mg/kg once daily. Max: 300 mg daily.
Oral HIV infection
Adult: In combination with other antiretrovirals: 300 mg once daily. Child: ≥2 years weighing >10 kg: 8 mg/kg once daily. Dosage recommendations may vary among individual products and between countries (refer to detailed product guideline).
Renal Impairment
Haemodialysis patients: 300 mg once every 7 days or after a cumulative total of 12 hours of dialysis.
CrCl (mL/min)
Dosage
10-29
300 mg 72-96 hourly.
30-49
300 mg 48 hourly.
Contraindications
Hypersensitivity. Lactation.
Special Precautions
Patient with risk factors for liver disease; coinfection with HIV and HBV. Renal and hepatic impairment. Pregnancy.
Adverse Reactions
Significant: Decreased bone mineral density, immune reconstitution syndrome, osteomalacia with proximal renal tubulopathy, acute renal failure and/or Fanconi syndrome. Gastrointestinal disorders: Diarrhoea, vomiting, nausea, abdominal pain, abdominal distention, flatulence. General disorders and administration site conditions: Asthenia, fatigue, fever. Metabolism and nutrition disorders: Hypophosphataemia. Nervous system disorders: Dizziness, headache. Psychiatric disorders: Insomnia, depression. Skin and subcutaneous tissue disorders: Rash, urticaria, pruritus. Potentially Fatal: Lactic acidosis, severe hepatomegaly with steatosis.
PO: Z (Current evidence suggests that tenofovir disoproxil does not increase the risk of pregnancy-related adverse effects. Tenofovir disoproxil is one of the recommended antiviral agents in management of HIV and/or hepatitis B during pregnancy.)
Patient Counseling Information
This drug may cause dizziness, if affected, do not drive or operate machinery.
Monitoring Parameters
Monitor renal function and serum phosphate concentrations before the start of therapy, within the first 4 weeks of treatment, after 3 months of treatment, and every 3-6 months thereafter; bone density at baseline and during treatment; LFT every 3 months during therapy and for several months following discontinuation. Determine HIV status in all hepatitis B virus (HBV) infected patients prior to treatment.
Drug Interactions
May decrease the plasma concentrations of atazanavir and increased plasma concentration of tenofovir disoproxil fumarate when given concomitantly. May increase the plasma concentrations of didanosine. Increased risk of nephrotoxicity with drugs that reduce renal function (e.g. cidofovir, aminoglycosides, amphotericin B, foscarnet, ganciclovir, pentamidine, vancomycin). Decreased therapeutic effect with adefovir.
Food Interaction
High fat meals may increase bioavailability of tenofovir.
Action
Description: Mechanism of Action: Tenofovir disoproxil fumarate (TDF) is a prodrug of tenofovir. It interferes with DNA synthesis of HIV through competitive inhibition of reverse transcriptase and incorporation into viral DNA. It also inhibits hepatitis B virus polymerase, resulting in inhibition of viral replication. Pharmacokinetics: Absorption: Rapidly absorbed from the gastrointestinal tract. Increased bioavailability when taken with a high fat meal. Bioavailability: Approx 25%. Time to peak plasma concentration: 36-84 minutes (fasting); 96-144 minutes (with high fat meal). Distribution: Widely distributed into body tissues, particularly the kidneys and liver. Volume of distribution: 1.2-1.3 L/kg. Plasma protein binding: <7%. Metabolism: Tenofovir disoproxil fumarate is rapidly converted intracellularly to tenofovir via hydrolysis, and subsequently phosphorylated to the active form, tenofovir diphosphate. Excretion: Via urine (70-80%, as unchanged drug). Elimination half-life: 17 hours.
Chemical Structure
Tenofovir disoproxil fumarate Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 6398764, Viread. https://pubchem.ncbi.nlm.nih.gov/compound/Viread. Accessed Feb. 23, 2021.
J05AF07 - tenofovir disoproxil ; Belongs to the class of nucleoside and nucleotide reverse transcriptase inhibitors. Used in the systemic treatment of viral infections.
References
Anon. Tenofovir Disoproxil Fumarate. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 04/02/2021.Buckingham R (ed). Tenofovir Disoproxil Fumarate. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 04/02/2021.Tenofovir Disoproxil Accordpharma 245 mg Film-coated Tablets (Accord Healthcare Limited). MHRA. https://products.mhra.gov.uk. Accessed 05/02/2021.Viread Tablet, Coated, Powder (Gilead Sciences, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 04/02/2021.
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