Tenofovir + Emtricitabine


Concise Prescribing Info
Indications/Uses
HIV-1 infection.
Dosage/Direction for Use
Adult : PO Per tab contains tenofovir disoproxil fumarate 300 mg and emtricitabine 200 mg: ≥18 yr: 1 tab once daily.
Dosage Details
Oral
HIV-1 infection
Adult: ≥18 yr: As tablet containing 200 mg of emtricitabine and 300 mg of tenofovir disoproxil fumarate: 1 tablet once daily. For patients with swallowing difficulties, tablet may be disintegrated in approx 100 ml of water, orange juice or grape juice and consumed immediately.
Renal Impairment
Patient on haemodialysis: Not recommended.
CrCl Dosage
<30 Not recommended.
30-49 1 tablet every 48 hr.
Administration
May be taken with or without food. Take consistently either always w/ or always w/o food.
Contraindications
Lactation. Not to be used for treatment of chronic hepatitis B virus (HBV) infection.
Special Precautions
Liver impairment. Renal impairment; avoid in CrCl <30ml/min and in patients on dialysis. Pregnancy. Not to be used with other emtricitabine, tenofovir disoproxil fumarate or other cytidine analogues (e.g. lamivudine and zalcitabine) preparations. Avoid use in antiretroviral-experienced patients with K65R mutation; in treatment experienced patients, use of combination drug to be guided by laboratory testing and treatment history. Increased risk for severe and potentially fatal hepatic adverse reactions in patients with HIV and hepatitis B or C virus co-infection treated with antiretroviral agents. If combination drug is discontinued in patients co-infected with HIV and HBV, monitor hepatic function for several months for acute exacerbation of hepatitis. Discontinue therapy if there is a rapid rise in aminotransferase concentrations, progressive hepatomegaly or steatosis, metabolic or lactic acidosis of unknown cause. Test for presence of chronic HBV before initiating therapy. Check CrCl before initiation of therapy and monitor renal function (CrCl and serum phosphate) every 4 wkly during the 1st year and then every 3 mthly (more frequently in patients at risk for renal impairment). Bone monitoring needed for patient with history of pathologic bone fracture or at risk of osteopenia. Monitor child exposed in utero to combination drug for possible mitochondrial dysfunction.
Adverse Reactions
Nausea, vomiting, diarrhoea, abdominal pain, dyspepsia, flatulence, pain, hypersensitivity, increased pigmentation, asthenia, osteonecrosis, osteomalacia, metabolic abnormalities (e.g. hyperglycaemia, insulin resistance, hypercholesterolaemia, hypertriglyceridaemia, hyperlactataemia), lipodystrophy, elevated lipase, amylase, creatine kinase or transaminases levels, hyperbilirubinaemia, insomnia, abnormal dreams. Neutropenia, anaemia, Immune Reactivation Syndrome. Renal impairment, acute renal failure, Fanconi syndrome.
Potentially Fatal: Lactic acidosis and severe hepatomegaly with steatosis.
Overdosage
Treatment is supportive and monitor for signs of toxicity. Haemodialysis may be helpful as it can remove up to 30% of the emtricitabine dose and 10% of the tenofovir dose. Unknown if peritoneal dialysis is useful.
Drug Interactions
Decreased atazanavir concentration with tenofovir unless also co-administered with ritonavir. Increased serum concentration of both tenofovir and emtricitabine or co-administered drug if taken with drugs that are eliminated by active tubular secretion.
Potentially Fatal: Increased risk of renal impairment with recent or concurrent use of nephrotoxic agents (e.g. aminoglycosides, amphotericin B, foscarnet, ganciclovir, pentamidine, vancomycin, cidofovir or interleukin-2); monitor renal function wkly if unavoidable. Increased didanosine levels and thereby increasing risk of pancreatitis and peripheral neuropathy, with a high treatment failure rate with concurrent use; avoid concurrent use. Do not use emtricitabine with lamivudine due to similar resistance profile. Increased risk of lactic acidosis with α-interferon.
Action
Description: Tenofovir disoproxil fumarate, a diester prodrug of tenofovir, is rapidly converted to tenofovir, an acyclic nucleoside phosphonate (nucleotide) analogue of adenosine 5'-monophosphate while emtricitabine is a synthetic nucleoside analogue of cytidine. Both emtricitabine and tenofovir inhibit HIV-1 reverse transcriptase, resulting in DNA chain termination.
Pharmacokinetics:
Absorption: Tenofovir: Rapidly absorbed; converted to tenofovir after oral doses; oral bioavailability: approx 25% after fasting, increased when taken with a high fat meal; peak plasma concentrations reached in 1 hr (fasting) to 2 hr (with food). Emtricitabine: Rapidly and well absorbed from GI tract; peak plasma concentrations achieved in 1-2 hours; bioavailability: 93% (capsules); 75% (oral solution).
Distribution: Tenofovir: Widely distributed into most tissues, especially kidneys, liver and intestinal contents; protein binding: <0.7% to plasma proteins, 7% to serum protein. Emtricitabine: Protein binding: <4%, independent of concentration.
Metabolism: Emtricitabine: Limited metabolism.
Excretion: Tenofovir: Excreted renally by glomerular filtration and active tubular secretion; terminal elimination half life: 12-18 hr. Emtricitabine: Excreted largely unchanged in the urine and to a lesser extent in the faeces; plasma elimination half-life: 10 hr.
Storage
Store between 15-30°C (59-86°F).
MIMS Class
Disclaimer: This information is independently developed by MIMS based on Tenofovir + Emtricitabine from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
  • Tenvir EM
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