Tenofovir

Pharmaceuticals -> Listed in ZINC15

Pharmaceuticals -> Metabolite of Tenofovir alafenamide, 'Tenofovir disoproxil

Danger

H318 (100%): Causes serious eye damage [Danger Serious eye damage/eye irritation]

P264+P265, P280, P305+P354+P338, and P317 (click each P-code to see the statement)

Aggregated GHS information provided per 2 reports by companies from 1 notifications to the ECHA C&L Inventory.

Like all nucleoside analogues used as therapy of hepatitis B, tenofovir can cause transient increases in serum aminotransferases during or after therapy. These abnormalities appear to be due to an exacerbation or flare of the underlying hepatitis B. Three types of flares due to nucleoside analogue therapy have been described: transient flares during initiation of therapy (treatment flares), flares occurring in association with development of antiviral resistance (breakthrough flares) and flares occurring in the few months after stopping therapy (withdrawal flares). Treatment flares generally arise during the first few months of starting therapy, are usually mild, asymptomatic and self-limited and do not require dose modification or interruption of therapy. Breakthrough flares generally follow the development of antiviral resistance and subsequent rise in HBV DNA levels during nucleoside analogue therapy. Breakthrough flares can be symptomatic and severe. Because tenofovir is associated with a very low rate of antiviral resistance (

Benchmark Dataset for the Liver Toxicity Knowledge Base (LTKB)

tenofovir

Viread®

Antivirals

8

most-DILI-concern

Tenofovir has been shown to be highly effective in patients that have never had an antiretroviral therapy and it seemed to have lower toxicity than other antivirals such as [stavudine]. In phase 3 clinical trials, tenofovir presented a similar efficacy than [efavirenz] in treatment-naive HIV patients. In hepatitis B infected patients, after one year of tenofovir treatment, the viral DNA levels were undetectable.

Once tenofovir is activated by a bi-phosphorylation it acts as an antiviral acyclic nucleoside phosphonate. It is a potent inhibitor of the viral reverse transcriptase with an inhibitory constant of approximately 0.022 micromolar. Once activated, tenofovir acts with different mechanisms including the inhibition of viral polymerase causing chain termination and the inhibition of viral synthesis. All these activities are attained by its competition with deoxyadenosine 5'-triphosphate in the generation of new viral DNA. Once tenofovir is incorporated in the chain, it induces a chain termination which in order inhibits viral replication. The safety of tenofovir relies on its low affinity towards the cellular DNA polymerase including the mitochondrial DNA polymerase gamma.

W4HFE001U5

TENOFOVIR ANHYDROUS

Established Pharmacologic Class [EPC] - Human Immunodeficiency Virus Nucleoside Analog Reverse Transcriptase Inhibitor

Established Pharmacologic Class [EPC] - Hepatitis B Virus Nucleoside Analog Reverse Transcriptase Inhibitor

Chemical Structure [CS] - Nucleosides

Mechanisms of Action [MoA] - Nucleoside Reverse Transcriptase Inhibitors

Agents used in the prophylaxis or therapy of VIRUS DISEASES. Some of the ways they may act include preventing viral replication by inhibiting viral DNA polymerase; binding to specific cell-surface receptors and inhibiting viral penetration or uncoating; inhibiting viral protein synthesis; or blocking late stages of virus assembly.

Inhibitors of reverse transcriptase (RNA-DIRECTED DNA POLYMERASE), an enzyme that synthesizes DNA on an RNA template.

Agents used to treat AIDS and/or stop the spread of the HIV infection. These do not include drugs used to treat symptoms or opportunistic infections associated with AIDS.

Tenofovir as the active moiety presents a very low bioavailability when orally administered. Hence, the administration of this active agent is required to be under its two prodrug forms, [tenofovir disoproxil] and [tenofovir alafenamide]. This reduced absorption is suggested to be related to the presence of two negative charges among its structure. This negative charge limits its cellular penetration, and its passive diffusion across cellular membranes and intestinal mucosa hindering its availability for oral administration. Intravenous tenofovir has been shown to produce a maximum plasma concentration of 2500 ng/ml with an AUC of 4800 ng.h/ml.

Tenofovir is eliminated in the urine by tubular secretion and glomerular filtration. The elimination of this compound is driven by the activity of the human organic anion transporters 1 and 3 and its secretion is mainly ruled by the activity of the multidrug resistance-associated protein 4.

Accumulation of tenofovir in plasma is related to the presence of nephrotoxic effects. It is reported that tenofovir presents a volume of distribution of 0.813 L/kg.

The clearance of tenofovir is highly dependent on the patient renal stage and hence the clearance rate in patients with renal impairment is reported to be of 134 ml/min while in patients with normal function the clearance rate can be of 210 ml/min.