Drug reference

Tenofovir

Antiretroviral · Treatment for Chronic Hepatitis B; Treatment for HIV

Also known as Tenofovir disoproxil

AntiretroviralTreatment for Chronic Hepatitis B; Treatment for HIV

CDSCO approvedSchedule H

EXCRETION

—

not curated

INTERACTIONS

1 major

incl. contraindicated

PREGNANCY

(see Useful

FDA category + note

Top interactionssee all 6 →

DidanosineContraindicatedTextbookG&G 14e · p1245-1266

Mechanism

Tenofovir is an acyclic adenosine nucleotide analogue that, unlike nucleoside analogues, already contains one phosphonate group and requires only two (rather than three) phosphorylation steps for activation. Tenofovir diphosphate competitively inhibits HIV-1 reverse transcriptase and HBV DNA polymerase, and is incorporated into viral DNA causing obligate chain termination. Its nucleotide (rather than nucleoside) structure provides reliable intracellular activation independent of the initial rate-limiting kinase step that can limit nucleoside analogue efficacy.

Indications

Initial treatment of chronic hepatitis BChronic hepatitis B in patients with decompensated liver diseaseLamivudine-resistant chronic hepatitis B (when given with lamivudine)Treatment for both HIV and chronic hepatitis B (as part of highly active antiretroviral therapy)HIV infection in adults and children older than 2 years in combination with other antiretroviral agentschronic hepatitis B in adults and children older than 12HIV preexposure prophylaxis (in combination with emtricitabine)chronic hepatitis B (especially lamivudine resistant cases)HIV (in combination regimens, including first line)

Dosing

Adult: in decompensated liver disease, but low doses can be used with great caution in these patients. Although interferon alfa is contra-indicated in patients receiving immunosuppressant treatment (or who have received it recently), cautious use of peginterferon alfa-2a may be justiﬁed in some cases. Entecavir p. 658 or tenofovir disoproxil p.…

Pharmacokinetics

Half-life

14–17

Bioavailability

25%

Protein binding

<8%

Excretion

70–80% (renal, unchanged)

Side effects

Common

flatulencenauseaabdominal discomfortloose motionsheadache

Serious

acute renal failure
Fanconi syndrome
declines in estimated creatinine clearance
rebound HBV replication
exacerbation of hepatitis
bone mineral density decreases
renal toxicity (rare, though slight increase in serum creatinine can occur)

Pregnancy & lactation

Pregnancy

(see Useful

Drug interactions

Didanosine

Contraindicated

Textbook

Increased exposure to didanosine, potentially leading to increased toxicity.

The two drugs should not be used together.

Source: G&G 14e · p1245-1266

Cobicistat

Moderate

Textbook

Tenofovir plasma concentrations are increased by 30% to 50%.

Generally well tolerated without producing significant renal injury, but caution with monitoring is advised.

Source: G&G 14e · p1245-1266

Ledipasvir

Moderate

Textbook

Increased plasma levels of tenofovir.

Renal function should be monitored in patients receiving both medications, although clinically significant interactions are unlikely during the relatively short period of treatment.

Source: Harrison 22e · unknown

Ritonavir

Moderate

Textbook

Tenofovir plasma concentrations are increased by 30% to 50%.

Generally well tolerated without producing significant renal injury, but caution with monitoring is advised.

Source: G&G 14e · p1245-1266

Acyclovir

Moderate

Database

Increased risk of renal dysfunction or worsening of pre-existing renal impairment

Monitor renal function closely, especially in patients with pre-existing renal impairment or other nephrotoxic agents. Consider dose adjustment for acyclovir or tenofovir based on renal function.

Nsaid

Moderate

Database

AKI, Fanconi syndrome

Avoid prolonged NSAID use. Monitor renal function.