Adult: Emtricitabine 200 mg and tenofovir disoproxil fumarate 300 mg tab
Emtricitabine 200 mg and tenofovir alafenamide 10 mg tab
Emtricitabine 200 mg and tenofovir alafenamide 25 mg tab
In combination with other antiretroviral agents: Patients weighing ≥35 kg: 1 tab once daily. Treatment recommendations may vary among countries (refer to latest local guidelines). Child: Emtricitabine 200 mg and tenofovir disoproxil fumarate 300 mg tab
Emtricitabine 200 mg and tenofovir alafenamide 10 mg tab
Emtricitabine 200 mg and tenofovir alafenamide 25 mg tab >12 years Same as adult dose. Treatment recommendations may vary among countries (refer to latest local guidelines).
Oral Pre-exposure prophylaxis of HIV
Adult: Emtricitabine 200 mg and tenofovir disoproxil fumarate 300 mg tab
In combination with safer sex practices in patients at high risk of HIV-1 infection: Patients weighing ≥35 kg: 1 tab once daily. Treatment recommendations may vary among countries (refer to latest local guidelines). Child: Emtricitabine 200 mg and tenofovir disoproxil fumarate 300 mg tab >12 years Same as adult dose. Treatment recommendations may vary among countries (refer to latest local guidelines).
What are the brands available for Emtricitabine + Tenofovir in Hong Kong?
HIV-1 infection: Emtricitabine and tenofovir disoproxil fumarate
Patient on haemodialysis: Not recommended.
CrCl (mL/min)
Dosage
<30
Not recommended.
30-49
1 tab 48 hourly.
Emtricitabine and tenofovir alfenamide
CrCl (mL/min)
Dosage
<30
Not recommended.
Pre-exposure prophylaxis of HIV: Emtricitabine and tenofovir disoproxil fumarate
CrCL (mL/min)
Dosage
<60
Not recommended.
Administration
Emtricitabine + Tenofovir May be taken with or without food. Emtricitabine + Tenofovir alafenamide film-coated tab: May be taken with or without food. Swallow whole, do not chew/crush/split. Emtricitabine + Tenofovir disoproxil phosphate tab: Should be taken with food.
Contraindications
Hypersensitivity. Unknown or positive HIV-1 status when use for HIV-1 pre-exposure prophylaxis. Lactation.
Special Precautions
Patient with hepatitis B or C virus infection, antiretroviral-experienced patients with HIV-1 harbouring the K65R mutation; history of pathologic bone fracture or predisposing factors for osteoporosis or bone loss (emtricitabine and tenofovir disoproxil fumarate). Renal and hepatic impairment. Pregnancy.
Adverse Reactions
Significant: Immune reconstitution syndrome or activation of autoimmune disorders (e.g. Graves' disease, polymyositis, Guillain-Barre syndrome, autoimmune hepatitis), renal toxicity (e.g. acute renal failure, Fanconi syndrome, proximal renal tubulopathy); decreased BMD. Blood and lymphatic system disorders: Anaemia. Gastrointestinal disorders: Diarrhoea, nausea, vomiting, abdominal pain, flatulence. General disorders and administration site conditions: Fatigue, asthenia. Immune system disorders: Allergic reaction. Investigations: Elevated creatine kinase; increased creatinine, transaminases, serum triglycerides; weight increased. Musculoskeletal and connective tissue disorders: Arthralgia, osteomalacia, osteonecrosis. Nervous system disorders: Headache, dizziness. Psychiatric disorders: Abnormal dreams, depression, insomnia. Skin and subcutaneous tissue disorders: Rash, angioedema, skin discolouration (particularly in children). Potentially Fatal: Lactic acidosis, severe hepatomegaly with steatosis; severe, acute exacerbation of hepatitis B (e.g. liver decompensation, liver failure) in HBV-infected individuals.
This drug may cause dizziness, if affected, do not drive or operate machinery.
Monitoring Parameters
Perform screening test for HIV-1 prior to initiation, then at least every 3 months during therapy, and upon diagnosis of any other STDs when use for HIV-1 preexposure prophylaxis. Perform screening test for HBV infection prior to therapy. Monitor CBC with differential, reticulocyte count, creatine kinase; D4 count, HIV RNA plasma levels; serum phosphorus (particularly in CKD patients); LFTs; weight (particularly in children); bone density (particularly in patients with history or predisposing factors for bone loss); serum creatinine, urine glucose, urine protein (prior to initiation and as clinically indicated).
Drug Interactions
Increased risk of nephrotoxicity with aminoglycosides, amphotericin B, foscarnet, ganciclovir, pentamidine, vancomycin, cidofovir, interleukin 2, high dose or multiple NSAIDS. Increased serum concentration of tenofovir with aciclovir, adefovir. Concomitant use of tenofovir disoproxil and atazanavir may result in decreased atazanavir concentration. Concomitant use of tenofovir disoproxil and didanosine may increase didanosine levels thereby increasing risk of pancreatitis and peripheral neuropathy.
Action
Description: Mechanism of Action: Emtricitabine and tenofovir both interfere with HIV viral RNA dependent DNA polymerase activities resulting in viral replication inhibition.
Emtricitabine is a HIV nucleoside reverse transcriptase inhibitor, a synthetic cytidine analogue which is intracellularly phosphorylated to its active metabolite, emtricitabine 5'- triphosphate.
Tenofovir is a HIV nucleotide reverse transcriptase inhibitor, an analog of adenosine 5'-monophosphate, is intracellularly converted to its active metabolite, tenofovir diphosphate which inhibits HBV polymerase leading to HBV replication inhibition. Pharmacokinetics: Absorption: Emtricitabine: Rapidly and extensively absorbed from the gastrointestinal tract. Time to peak plasma concentration: 1-2 hours. Bioavailability: 93%.
Tenofovir alafenamide: Rapidly absorbed from the gastrointestinal tract. Bioavailability: Approx 65% (with high-fat meal). Time to peak plasma concentration: Approx 1 hour. Tenofovir disoproxil fumarate: Rapidly absorbed from the gastrointestinal tract. Bioavailability: Approx 25% (fasting); approx 40% (with high-fat meal). Time to peak plasma concentration: 35-84 minutes (fasting); 96-144 minutes (with high-fat meal). Distribution: Present in breastmilk.
Emtricitabine: Plasma protein binding: 4%.
Tenofovir: Widely distributed into the tissues, particularly in the kidneys and liver. Plasma protein binding: <1%. Tenofovir alafenamide: Plasma protein binding: Approx 80%. Tenofovir disoproxil fumarate: Volume of distribution: 1.2-1.3 L/kg. Plasma protein binding: 7%, to serum proteins. Metabolism: Emtricitabine: Undergoes minimal metabolism via oxidation and glucuronide conjugation; converted intracellularly to its active triphosphate form.
Tenofovir alafenamide: Metabolised intracellularly to tenofovir, then phosphorylated to its active form, tenofovir diphosphate. Tenofovir disoproxil fumarate: Metabolised intracellularly via hydrolysis by non-CYP enzyme to tenofovir then phosphorylated to its active form, tenofovir diphosphate. Excretion: Emtricitabine: Mainly via urine (86% primarily as unchanged drug, 13% as metabolites; 9% as oxidative metabolite; 4% as glucuronide metabolite); faeces (14%). Elimination half-life: Approx 10 hours.
Tenofovir alafenamide: Via faeces (31.7%); urine (1%). Elimination half-life: 0.51 hour. Tenofovir disoproxil fumarate: Mainly via urine (70-80%, mainly as unchanged drug). Elimination half-life: 17 hours.
Chemical Structure
Emtricitabine Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 60877, Emtricitabine. https://pubchem.ncbi.nlm.nih.gov/compound/Emtricitabine. Accessed Nov. 26, 2024.
Tenofovir alafenamide Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 9574768, Tenofovir Alafenamide. https://pubchem.ncbi.nlm.nih.gov/compound/gs-7340. Accessed Nov. 26, 2024.
Tenofovir disoproxil fumarate Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 6398764, Tenofovir Disoproxil Fumarate. https://pubchem.ncbi.nlm.nih.gov/compound/Tenofovir-Disoproxil-Fumarate. Accessed Nov. 26, 2024.
J05AR03 - tenofovir disoproxil and emtricitabine ; Belongs to the class of antivirals for treatment of HIV infections, combinations. J05AR17 - emtricitabine and tenofovir alafenamide ; Belongs to the class of antivirals for treatment of HIV infections, combinations.
References
Anon. Emtricitabine and Tenofovir Alafenamide Fumarate. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 20/05/2024.Anon. Emtricitabine and Tenofovir Disoproxil Fumarate. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 20/05/2024.Buckingham R (ed). Emtricitabine. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 20/05/2024.Buckingham R (ed). Tenofovir. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 20/05/2024.Descovy 200 mg/10 mg Film-coated Tablets (Gilead Sciences Ltd). MHRA. https://products.mhra.gov.uk. Accessed 22/11/2024.Emtricitabine and Tenofovir Alafenamide. UpToDate Lexidrug, Lexi-Drugs Multinational Online. Waltham, MA. UpToDate, Inc. https://online.lexi.com. Accessed 20/05/2024.Emtricitabine and Tenofovir Disoproxil Fumarate Tablet, Film Coated (Zydus Pharmaceuticals USA Inc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 20/05/2024.Emtricitabine and Tenofovir Disoproxil Fumarate. UpToDate Lexidrug, Lexi-Drugs Multinational Online. Waltham, MA. UpToDate, Inc. https://online.lexi.com. Accessed 20/05/2024.Emtricitabine. UpToDate Lexidrug, Lexi-Drugs Multinational Online. Waltham, MA. UpToDate, Inc. https://online.lexi.com. Accessed 20/05/2024.Emtricitabine/Tenofovir Disoproxil Tillomed 200 mg/245 mg Film-coated Tablets (Tillomed Laboratories Limited). MHRA. https://products.mhra.gov.uk. Accessed 20/05/2024.Fostavir-EM 200 mg/300 mg Tablets (Unimed Sdn Bhd). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 20/05/2024.Gilead Sciences (NZ). Descovy Tablets 200 mg/25 mg, 200 mg/10 mg data sheet 15 March 2022. Medsafe. http://www.medsafe.govt.nz. Accessed 20/05/2024.Joint Formulary Committee. Emtricitabine with Tenofovir Alafenamide. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 20/05/2024.Joint Formulary Committee. Emtricitabine with Tenofovir Disoproxil. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 20/05/2024.Taficita Tablets 200 mg/25 mg (Mylan Healthcare Sdn. Bhd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 20/05/2024.Tenofovir Alafenamide. UpToDate Lexidrug, Lexi-Drugs Multinational Online. Waltham, MA. UpToDate, Inc. https://online.lexi.com. Accessed 20/05/2024.Tenofovir Disoproxil Fumarate. UpToDate Lexidrug, Lexi-Drugs Multinational Online. Waltham, MA. UpToDate, Inc. https://online.lexi.com. Accessed 20/05/2024.Viatris Ltd. Tenofovir Disoproxil Emtricitabine Viatris 300 mg/200 mg Film Coated Tablets data sheet 09 June 2022. Medsafe. http://www.medsafe.govt.nz. Accessed 20/05/2024.
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