Chronic hepatitis B virus (HBV) infection in adults with compensated liver disease.
Nucleoside reverse transcriptase inhibitors (NRTIs)
Tenofovir alafenamide is a phosphonamidate prodrug of tenofovir (2’-deoxyadenosine monophosphate analog). Tenofovir alafenamide as a lipophilic cell-permeant compound enters primary hepatocytes by passive diffusion and by the hepatic uptake transporters OATP1B1 and OATP1B3. Tenofovir alafenamide is then converted to tenofovir through hydrolysis primarily by carboxylesterase 1 (CES1) in primary hepatocytes. Intracellular tenofovir is subsequently phosphorylated by cellular kinases to the pharmacologically active metabolite tenofovir diphosphate. Tenofovir diphosphate inhibits HBV replication through incorporation into viral DNA by the HBV reverse transcriptase, which results in DNA chain termination. Tenofovir diphosphate is a weak inhibitor of mammalian DNA polymerases that include mitochondrial DNA polymerase γ and there is no evidence of toxicity to mitochondria in cell culture.
\"Adult: Take with food. ≥18yrs: 1 tab once daily. Concomitant carbamazepine: 2 tabs once daily. Children: <18yrs: not established.\"
Potential for Other Drugs to Affect Tenofovir alafenamide: Tenofovir alafenamide is a substrate of P-glycoprotein (P-gp) and BCRP. Drugs that strongly affect P-gp and BCRP activity may lead to changes in tenofovir alafenamide absorption. Drugs that induce P-gp activity are expected to decrease the absorption of tenofovir alafenamide resulting in decreased plasma concentrations of tenofovir alafenamide which may lead to loss of therapeutic effect of Tenofovir alafenamide. Coadministration of Tenofovir alafenamide with other drugs that inhibit P-gp and BCRP may increase the absorption & plasma concentration of tenofovir alafenamide.
Drugs Affecting Renal Function: Tenofovir is primarily excreted by the kidneys by a combination of glomerular filtration and active tubular secretion, coadministration of Tenofovir alafenamide with drugs that reduce renal function or compete for active tubular secretion may increase concentrations of tenofovir and other renally eliminated drugs and this may increase the risk of adverse reactions. Some examples of drugs that are eliminated by active tubular secretion include but are not limited to acyclovir, cidofovir, ganciclovir, valacyclovir, valganciclovir, aminoglycosides (e.g., gentamicin) and high-dose or multiple NSAIDs.
Concomitant drugs that strongly affect P-gp and BCRP activity may lead to changes in TAF absorption. Caution with concomitant nephrotoxic agents. Antagonized by carbamazepine (see Adults). Concomitant oxcarbazepine, phenobarbital, phenytoin, rifabutin, rifampin, rifapentine, St. John\'s wort: not recommended. May be potentiated by drugs that decrease renal function or compete for active tubular secretion (eg, acyclovir, cidofovir, ganciclovir, valacyclovir, valganciclovir, aminoglycosides)
Headache, abdominal pain, fatigue, cough, nausea, back pain.
There are no human data on the use of Tenofovir alafenamide in pregnant women to inform a drug-associated risks of adverse fetal developmental outcome. In animal studies, no adverse developmental effects were observed when tenofovir alafenamide was administered during the period of organogenesis at exposure equal to or 51 times (rats and rabbits, respectively) the tenofovir alafenamide exposure at the recommended daily dose of Tenofovir alafenamide
If overdose occurs, monitor patient for evidence of toxicity. Treatment of overdosage with Tenofovir alafenamide consists of general supportive measures including monitoring of vital signs as well as observation of the clinical status of the patient. Tenofovir is efficiently removed by hemo- dialysis with an extraction coefficient of approximately 54%.
Store below 30°C. Keep it in its original container. protect from light. Keep out of children’s reach.
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