Which medications in the drug class Antihepadnaviral, Reverse Transcriptase inhibitors are used in the treatment of Hepatitis B?

Updated: Aug 01, 2018
  • Author: Nikolaos T Pyrsopoulos, MD, PhD, MBA, FACP, AGAF; Chief Editor: BS Anand, MD  more...
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Answer

Antihepadnaviral, Reverse Transcriptase inhibitors

Antiviral agents interfere with viral replication and weaken or abolish viral activity.

Tenofovir disoproxil fumarate (Viread)

Tenofovir is a nucleotide analogue (adenosine monophosphate) reverse transcriptase and hepatitis B virus (HBV) polymerase inhibitor.

Tenofovir may be used as first-line therapy for treatment-naïve patients. It is preferred as additional therapy in patients with lamivudine, telbivudine, or entecavir resistance. This agent has more potent antiviral activity than adefovir and can be used as a substitute in patients who do not have an adequate response to adefovir.

Entecavir (Baraclude)

Entecavir is a guanosine nucleoside analogue with activity against hepatitis B virus (HBV) polymerase. This agent competes with the natural substrate deoxyguanosine triphosphate (dGTP) to inhibit HBV polymerase activity (ie, reverse transcriptase). Entecavir is less effective for lamivudine-refractory HBV infection. This drug is indicated for treatment of chronic HBV infection and is available as a tablet and as an oral solution (0.05 mg/mL; 0.5 mg = 10 mL).

Lamivudine (Epivir, Epivir-HBV)

Lamivudine is a thymidine analogue that blocks viral replication by competitive inhibition of viral reverse transcriptase. There is evidence that an indirect immunomodulatory effect can be observed.

Relative to other oral treatments, lamivudine is lower in cost. Other agents, however, except for adefovir, are superior to lamivudine in suppression of viral replication. Another disadvantage to this therapy includes its high rate of drug resistance. The role of lamivudine in hepatitis B treatment is diminishing as alternate therapies become available.

Adefovir dipivoxil (Hepsera)

Adefovir is used to treat chronic hepatitis B disease. This agent is a prodrug that is converted to the diphosphate salt. The active drug is classified as an antiviral nucleotide reverse transcriptase inhibitor. It inhibits hepatitis B virus (HBV) DNA polymerase (reverse transcriptase) by competing with the natural substrate deoxyadenosine triphosphate (dATP) and by causing DNA chain termination after its incorporation into viral DNA.

Telbivudine (Tyzeka)

Telbivudine is a nucleoside analogue approved by the US Food and Drug Administration (FDA) for chronic hepatitis B treatment. This drug inhibits hepatitis B viral DNA polymerase and is indicated for patients with evidence of ongoing hepatitis B viral replication and either persistently elevated aminotransferase activity or histologic evidence of active liver disease. Consider telbivudine for patients whose condition does not or is unlikely to respond to interferon or for patients who cannot tolerate interferon. Emergence of resistance is a major drawback of nucleoside analogue monotherapy.

Tenofovir AF (Vemlidy)

Tenofovir alafenamide (TAF) is a nucleotide reverse transcriptase inhibitor (NRTI) and a phosphonamidate prodrug of tenofovir. TAF, as a lipophilic cell-permeant compound, enters primary hepatocytes by passive diffusion and by the hepatic uptake transporters OATP1B1 and OATP1B3, and it 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.

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

It is indicated for the treatment of chronic HBV infection in adults with compensated liver disease.


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