tenofovir AF (Rx)

Brand and Other Names:Vemlidy
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

tablet

  • 25mg

Chronic Hepatitis B Infection

Indicated for treatment of chronic hepatitis B virus (HBV) infection in adults with compensated liver disease

25 mg PO qDay with food

Dosage Modifications

Renal impairment

  • Mild, moderate, or severe: No dosage adjustment required
  • ESRD (CrCl <15 mL/min): Use not recommended in patients who are not receiving hemodialysis; in patients receiving chronic hemodialysis, administer drug after completion of hemodialysis

Hepatic impairment

  • Mild (Child-Pugh A): No dosage adjustment required
  • Decompensated (Child-Pugh B or C) hepatic impairment: Use not recommended

Dosing Considerations

Test for HIV-1 infection before initiating; tenofovir alone should not be used in patients with HIV infection

Assess serum creatinine, phosphorous, estimated CrCl, urine glucose, and urine protein before initiating and periodically throughout treatment

<18 years: Safety and efficacy not established

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Interactions

Interaction Checker

and tenofovir AF

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    No Interactions Found
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    Contraindicated

      Serious - Use Alternative

        Significant - Monitor Closely

          Minor

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            Adverse Effects

            >10%

            Headache (9-12%)

            Bone mineral density decline (5-11%)

            1-10%

            Abdominal pain (7-9%)

            ALT >5 x ULN (8%)

            Cough (8%)

            Fatigue (6%)

            Nausea (6%)

            LDL-cholesterol fasted >190 mg/dL (6%)

            Back pain (6%)

            Glycosuria ≥3+ (5%)

            Nausea (5%)

            Arthralgia (5%)

            Diarrhea (5%)

            Dyspepsia (5%)

            AST >5 x ULN (3%)

            Creatine kinase ≥10 x ULN (3%)

            Serum amylase >2 x ULN (3%)

            Frequency Not Defined

            Severe acute exacerbation of hepatitis B in patients with HBV infection

            Postmarketing Reports

            Skin and subcutaneous tissue disorders: Angioedema, urticaria

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            Warnings

            Black Box Warnings

            Hepatitis B exacerbation

            • Severe acute exacerbations of hepatitis B reported in patients who have discontinued therapy for hepatitis B
            • Hepatic function should be monitored closely with both clinical and laboratory follow-up for at least several months in patients who discontinue therapy
            • Resumption of therapy for hepatitis B may be warranted

            Lactic acidosis

            • Lactic acidosis and severe hepatomegaly with steatosis (including fatal cases) reported with use of nucleoside analogues alone or in combination

            Contraindications

            None

            Cautions

            Lactic acidosis and severe hepatomegaly with steatosis, including fatalities, reported with nucleoside analogs, including tenofovir disoproxil fumarate in combination with other antiretrovirals; most were reported in women; obesity and prolonged nucleoside exposure may be risks factors (see Black Box Warnings)

            Discontinuation of antihepatitis B drugs may result in severe acute exacerbations of hepatitis B (see Black Box Warnings); all patients should be tested for presence of chronic hepatitis B virus (HBV) before or when initiating therapy

            Resumption of anti-hepatitis B therapy may be warranted, in patients with advanced liver disease or cirrhosis, since posttreatment exacerbation of hepatitis may lead to hepatic decompensation and liver failure

            Owing to the risk of development of HIV-1 resistance, tenofovir AF alone is not recommended for the treatment of HIV-1 infection; test for HIV-1 before initiating treatment

            Persistent or worsening bone pain, pain in extremities, fractures and/or muscular pain or weakness may be manifestations of proximal renal tubulopathy and should prompt an evaluation of renal function in patients at risk of renal dysfunction

            Renal impairment, including cases of acute renal failure and Fanconi syndrome (renal tubular injury with severe hypophosphatemia), has been reported with the use of tenofovir prodrugs; this has not been observed with tenofovir AF in clinical trials; prior to or when initiating therapy, and during treatment on a clinically appropriate schedule, assess serum creatinine, estimated creatinine clearance, urine glucose, and urine protein in all patients; in patients with chronic kidney disease, also assess serum phosphorus; discontinue therapy in patients who develop clinically significant decreases in renal function or evidence of Fanconi syndrome

            Drug interaction overview

            • P-gp and BCRP
              • P-gp and BCRP substrate; drugs that strongly affect these transporters may lead to changes in tenofovir AF absorption
              • Drugs that induce P-gp result in decreased tenofovir AF absorption and plasma concentrations, which may lead to loss of therapeutic effect (eg, carbamazepine, oxcarbazepine, phenobarbital, phenytoin, rifabutin, rifampin, rifapentine, St John’s wort)
              • Drugs that inhibit P-gp and BCRP may increase tenofovir AF absorption and plasma concentration
            • Drugs affecting renal function
              • Tenofovir is primarily excreted by the kidneys by a combination of glomerular filtration and active tubular secretion
              • Coadministration of tenofovir AF 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 include acyclovir, cidofovir, ganciclovir, valacyclovir, valganciclovir, aminoglycosides, high-dose or long-term NSAD use
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            Pregnancy

            Pregnancy

            There are no human data on use 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

            Lactation

            Unknown if distributed in human breast milk

            Consider the developmental and health benefits of breastfeeding along with the mother’s clinical need for the drug, and any potential adverse effects on the breastfed infant from the drug or from the underlying maternal condition

            Pregnancy Categories

            A:Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

            B:May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

            C:Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

            D:Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

            X:Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

            NA:Information not available.

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            Pharmacology

            Mechanism of Action

            Tenofovir alafenamide (AF) is a nucleotide reverse transcriptase inhibitor (NRTI) and a phosphonamidate prodrug of tenofovir

            Compared with tenofovir disoproxil fumarate (tenofovir DF, Viread), tenofovir AF is a more targeted form of tenofovir that has demonstrated high antiviral efficacy at a dose that is 10 times lower than tenofovir DF, as well as an improved renal and bone safety profile

            Tenofovir AF as a lipophilic cell-permeant compound enters primary hepatocytes by passive diffusion and by the hepatic uptake transporters OATP1B1 and OATP1B3 and is converted to tenofovir diphosphate

            Tenofovir diphosphate inhibits HBV replication through incorporation into viral DNA by the HBV reverse transcriptase, which results in DNA chain-termination

            Absorption

            Peak plasma time: ~30 minutes

            Distribution

            Protein bound: 80%

            Metabolism

            Converted from tenofovir AF to tenofovir through hydrolysis primarily by carboxyesterase 1 (CES1) in primary hepatocytes

            Intracellular tenofovir is subsequently phosphorylated by cellular kinases to the pharmacologically active metabolite tenofovir diphosphate

            Also metabolized by Cathepsin A in peripheral blood mononuclear cells (PBMCs)

            CYP3A: Minimal

            Elimination

            Half-life: 0.5 hr

            Excretion: <1% urine; 31.7% feces

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            Administration

            Oral Administration

            Take with food

            Inform patients to take on a regular dosing schedule and to avoid missing doses, as it can result in development of resistance

            Storage

            Store at controlled room temperature <30°C (86°F)

            Keep container tightly closed

            Dispense only in original container

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            Formulary

            FormularyPatient Discounts

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            The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

            Tier Description
            1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
            2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
            3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
            4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            NC NOT COVERED – Drugs that are not covered by the plan.
            Code Definition
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            Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.