HIV-1/2 nucleotide reverse transcriptase

In the MTT experiment, tenofovir exhibits cytotoxic effects on HK-2 cell viability, with IC50 values of 2.77 μM at 48 and 72 hours, respectively. Tenofovir causes HK-2 cells' ATP levels to drop. In HK-2 cells, tenofovir (3.0 to 28.8 μM) elevates protein carbonylation and oxidative stress. Moreover, tenofovir causes HK-2 cells to undergo apoptosis, and this process is brought on by mitochondrial damage[1]. The replication of R5-tropic HIV-1BaL and X4-tropic HIV-1IIIb in activated PBMCs is inhibited by tenofovir and M48U1, when compounded in 0.25% HEC. Additionally, various laboratory strains and patient-derived HIV-1 isolates are inhibited. Infection with R5-tropic HIV-1BaL is inhibited by the synergistic antiretroviral action of M48U1 and tenofovir coupled in 0.25% HEC, and this formulation is not harmful to PBMCs[2].

When given to BLT mice (20, 50, 140, or 300 mg/kg), tenofovir Disoproxil fumarate exhibits dose-dependent efficacy in response to a vaginal HIV challenge in BLT humanized mice. In BLT mice, tenofovir Disoproxil fumarate (50, 140, or 300 mg/kg) dramatically lowers HIV transmission[3]. In woodchucks with a chronic WHV infection, tenofovir Disoproxil fumarate (0.5, 1.5, or 5.0 mg/kg/day, po) causes a dose-dependent decrease in serum viremia. The treatment of tenofovir Disoproxil fumarate in the woodchuck model of chronic HBV infection is both safe and effective[4].

Cell Viability Assay[2]
Cell viability was determined using the Cell Counting Kit-8 (CCK-8). Mouse NPCs were seeded on 96-well plates with a density of 1 × 104 cells per well. After overnight incubation, cells were treated with either DMSO (0.55 mg/ml, negative control), cytosine β-D-arabinofuranoside (Ara-C, 7 μg/ml, positive control), or various concentrations of antiretroviral drugs (0.1×, 0.3×, 0.5×, and 1×). Half of the medium liquid was renewed every three days. On day 2, 4, 6, and 8, 10 μl CCK-8 solution was added into each well of cell culture and the plates were incubated for another 2 h at 37 °C. The optical density was then measured at an absorbance of 450 nm using a microplate reader. Culture medium without cells served as a blank control. Cell viability was calculated using the following equation: cell viability = (OD drug treated group - OD blank) / (OD DMSO treated group - OD blank). Experiments were performed in triplicates and repeated at least three times independently.[2]

---

Western Blotting[2]
Mouse NPCs were lysed by M-PER Protein Extraction Buffer (Pierce). Total protein concentration was determined using the Bicinchoninic Acid (BCA) Protein Assay Kit (Pierce). Analytical SDS-polyacrylamide gel electrophoresis (SDS-PAGE) was performed using 10% and 15% gels. Proteins were then transferred onto an Immuno-Blot polyvinylidene fluoride membrane (Bio-Rad). After blocked in 5% fat-free milk for 1 h, the membrane was incubated with primary antibodies for Caspase-3 (1:1000; Cell Signaling Technologies), poly ADP-ribose polymerase (PARP, 1:1000; Cell Signaling Technologies), and Actin (1:5000; Sigma-Aldrich) overnight at 4 °C followed by horseradish peroxidase-conjugated secondary antibodies for 1 h at room temperature. Protein signals were detected using a chemiluminescent substrate solution. The density of each band was determined by Image Lab software and analyzed using Image J program.[2]

Drug Treatment[2]
For in vivo studies, 10-week-old C57BL/6 mice were randomly assigned to two groups (n = 6 for each group). One group received TDF/FTC/RAL combined medication (104/120/28 mg/kg, TDF and RAL were dissolved in DMSO, FTC in 0.9% NaCl) while the other received vehicle control (DMSO and 0.9% NaCl) via daily intraperitoneal (i.p.) injections for 60 days. The dose used in this study is within the range of drug concentrations used in other mouse studies (Denton et al. 2012) and mice were weighed daily to adjust drug intake.[2]
For in vitro studies, mouse NPCs were treated with antiretroviral drugs (dissolved in DMSO) in combination or individually at various concentrations. 1×: 1 μg/ml for TDF, 2 μg/ml for FTC, and 0.1 μg/ml for RAL. 0.1×, 0.3×, 0.5×, 3×, 5×, and 10× were calculated based on 1× concentrations. Control group was treated with DMSO (0.55 mg/ml)[2]

---

Tenofovir disoproxil fumarate (TDF) is a nucleotide analogue approved for treatment of human immunodeficiency virus (HIV) infection. TDF also has been shown in vitro to inhibit replication of wild-type hepatitis B virus (HBV) and lamivudine-resistant HBV mutants and to inhibit lamivudine-resistant HBV in patients and HBV in patients coinfected with the HIV. Data on the in vivo efficacy of TDF against wild-type virus in non-HIV-coinfected or lamivudine-naïve chronic HBV-infected patients are lacking in the published literature. The antiviral effect of oral administration of TDF against chronic woodchuck hepatitis virus (WHV) infection, an established and predictive animal model for antiviral therapy, was evaluated in a placebo-controlled, dose-ranging study (doses, 0.5 to 15.0 mg/kg of body weight/day). Four weeks of once-daily treatment with TDF doses of 0.5, 1.5, or 5.0 mg/kg/day reduced serum WHV viremia significantly (0.2 to 1.5 log reduction from pretreatment level). No effects on the levels of anti-WHV core and anti-WHV surface antibodies in serum or on the concentrations of WHV RNA or WHV antigens in the liver of treated woodchucks were observed. Individual TDF-treated woodchucks demonstrated transient declines in WHV surface antigen serum antigenemia and, characteristically, these woodchucks also had transient declines in serum WHV viremia, intrahepatic WHV replication, and hepatic expression of WHV antigens. No evidence of toxicity was observed in any of the TDF-treated woodchucks. Following drug withdrawal there was prompt recrudescence of WHV viremia to pretreatment levels. It was concluded that oral administration of TDF for 4 weeks was safe and effective in the woodchuck model of chronic HBV infection.[5]

---

Dissolved in saline; 30 mg/kg; s.c. injection

Macaques

Absorption, Distribution and Excretion
Following IV administration of tenofovir, approximately 70-80% of the dose is recovered in the urine as unchanged tenofovir within 72 hours of dosing. Following single dose, oral administration of tenofovir, the terminal elimination half-life of tenofovir is approximately 17 hours. After multiple oral doses of tenofovir 300 mg once daily (under fed conditions), 32 + or - 10% of the administered dose is recovered in urine over 24 hours. Tenofovir is eliminated by a combination of glomerular filtration and active tubular secretion. There may be competition for elimination with other compounds that are also renally eliminated.
In vitro binding of tenofovir to human plasma or serum proteins is less than 0.7 and 7.2%, respectively, over the tenofovir concentration range 0.01 to 25 ug/mL. The volume of distribution at steady-state is 1.3 + or - 0.6 L/kg and 1.2 + or - 0.4 L/kg, following intravenous administration of tenofovir 1.0 mg/kg and 3.0 mg/kg.
Viread is a water soluble diester prodrug of the active ingredient tenofovir. The oral bioavailability of tenofovir from Viread in fasted subjects is approximately 25%. Following oral administration of a single dose of Viread 300 mg to HIV-1 infected subjects in the fasted state, maximum serum concentrations (Cmax) are achieved in 1.0 + or - 0.4 hr. Cmax and AUC values are 0.30 + or - 0.09 ug/mL and 2.29 + or - 0.69 ug hr/mL, respectively.
Administration of Viread 300 mg tablets following a high-fat meal (approximately 700 to 1000 kcal containing 40 to 50% fat) increases the oral bioavailability, with an increase in tenofovir AUC of approximately 40% and an increase in Cmax of approximately 14%. However, administration of Viread with a light meal did not have a significant effect on the pharmacokinetics of tenofovir when compared to fasted administration of the drug. Food delays the time to tenofovir Cmax by approximately 1 hour. Cmax and AUC of tenofovir are 0.33 + or - 0.12 ug/mL and 3.32 + or - 1.37 ug hr/mL following multiple doses of Viread 300 mg once daily in the fed state, when meal content was not controlled.
For more Absorption, Distribution and Excretion (Complete) data for TENOFOVIR DISOPROXIL FUMARATE (6 total), please visit the HSDB record page.

---

Metabolism / Metabolites
Tenofovir disoproxil fumarate is a prodrug and is not active until it undergoes diester hydrolysis in vivo to tenofovir and subsequently is metabolized to the active metabolite (tenofovir diphosphate).

---

Biological Half-Life
Following single dose, oral administration of Viread, the terminal elimination half-life of tenofovir is approximately 17 hours.

Interactions
Potential pharmacokinetic interaction with drugs that reduce renal function or that may compete with tenofovir for active renal tubular secretion (i.e., acyclovir, cidofovir, ganciclovir, valacyclovir, valganciclovir); increased plasma concentrations of tenofovir or the concomitantly administered drug may occur.
The manufacturer of tenofovir states that tenofovir should not be used with adefovir for the treatment of hepatitis B virus (HBV) infection.
Pharmacokinetic interaction with atazanavir sulfate (decrease plasma concentrations and AUC of atazanavir (minimum concentration decreased 40%) and increased plasma concentrations and AUC of tenofovir when atazanavir 400 mg and tenofovir disoproxil fumarate 300 mg given once daily). Pharmacokinetic interaction with ritonavir-boosted atazanavir sulfate (decrease plasma concentrations and AUC of atazanavir (minimum concentration decreased 23%) and increased plasma concentrations and AUC of tenofovir when atazanavir 300 mg, ritonavir 100 mg, and tenofovir disoproxil fumarate 300 mg given once daily). If used concomitantly, a dosage regimen of atazanavir 300 mg, ritonavir 100 mg, and tenofovir disoproxil fumarate 300 mg given once daily with food is recommended; atazanavir should not be used with tenofovir unless low-dose ritonavir is a component of the regimen. Monitor for tenofovir toxicity and discontinue the drug if tenofovir-associated adverse effects occur. If atazanavir is used concomitantly with tenofovir and a histamine H2-receptor antagonist, the recommended dosage for treatment-experienced patients is atazanavir 400 mg, ritonavir 100 mg, and tenofovir disoproxil fumarate 300 mg given once daily with food.
Pharmacokinetic interaction with the buffered didanosine preparation (pediatric oral solution admixed with antacid; Videx) or delayed-release capsules containing enteric-coated pellets of didanosine (Videx EC) resulting in increased plasma concentrations and AUC of didanosine; no change in tenofovir pharmacokinetics. Potential for early virologic failure, rapid selection of resistant mutations, immunologic nonresponse (e.g., decline in CD4+ T-cell count), and increased risk of didanosine-associated adverse effects (e.g., pancreatitis, neuropathy). Caution is advised if didanosine and tenofovir are used concomitantly and patients should be monitored closely for didanosine-associated adverse effects; didanosine should be discontinued if such effects occur. If didanosine delayed-release capsules are used with tenofovir disoproxil fumarate, the recommended dosage of didanosine is 250 mg once daily for those weighing 60 kg or more with creatinine clearances of 60 mL/minute or greater and 200 mg once daily for those weighing less than 60 kg with creatinine clearances of 60 mL/minute or greater. Didanosine delayed-release capsules and tenofovir may be taken at the same time with a light meal (no more than 400 kcal, no more than 20% fat) or in the fasted state.
For more Interactions (Complete) data for TENOFOVIR DISOPROXIL FUMARATE (10 total), please visit the HSDB record page.

[1]. Establishment of HK-2 Cells as a Relevant Model to Study Tenofovir-Induced Cytotoxicity. Int J Mol Sci. 2017 Mar 1;18(3).

[2]. Combined Medication of Antiretroviral Drugs Tenofovir Disoproxil Fumarate, Emtricitabine, and Raltegravir Reduces Neural Progenitor Cell Proliferation In Vivo and In Vitro. J Neuroimmune Pharmacol. 2017 Dec;12(4):682-692.

[3]. M48U1 and Tenofovir combination synergistically inhibits HIV infection in activated PBMCs and human cervicovaginal histocultures. Sci Rep. 2017 Feb 1;7:41018.

[4]. Predicting HIV Pre-exposure Prophylaxis Efficacy for Women using a Preclinical Pharmacokinetic-Pharmacodynamic In Vivo Model. Sci Rep. 2017 Feb 1;7:41098.

[5]. Menne S, Cote PJ, Korba BE, Antiviral effect of oral administration of tenofovir disoproxil fumarate in woodchucks with chronic woodchuck hepatitis virus infection. Antimicrob Agents Chemother. 2005 Jul;49(7):2720-8.

Therapeutic Uses
Anti-HIV Agents, Reverse Transcriptase Inhibitors
Tenofovir disoproxil fumarate is used in conjunction with other antiretroviral agents for the treatment of human immunodeficiency virus type 1 (HIV-1) infections in adults. /Included in US product labeling/
Tenofovir is used for the management of chronic hepatitis B virus (HBV) infection in adults. This indication is based on histologic, virologic, biochemical, and serologic responses in adults with hepatitis B e antigen (HBeAg)-positive or -negative chronic HBV with compensated liver function.
Tenofovir disoproxil fumarate (TDF), emtricitabine (FTC), and efavirenz (EFV) are the three components of the once-daily, single tablet regimen (Atripla) for treatment of HIV-1 infection. Previous cell culture studies have demonstrated that the double combination of tenofovir (TFV), the parent drug of TDF, and FTC were additive to synergistic in their anti-HIV activity, which correlated with increased levels of intracellular phosphorylation of both compounds. In this study, /researchers/ demonstrated the combinations of TFV+FTC, TFV+EFV, FTC+EFV, and TFV+FTC+EFV synergistically inhibit HIV replication in cell culture and synergistically inhibit HIV-1 reverse transcriptase (RT) catalyzed DNA synthesis in biochemical assays. Several different methods were applied to define synergy including median-effect analysis, MacSynergyII and quantitative isobologram analysis. We demonstrated that the enhanced formation of dead-end complexes (DEC) by HIV-1 RT and TFV-terminated DNA in the presence of FTC-triphosphate (TP) could contribute to the synergy observed for the combination of TFV+FTC, possibly through reduced terminal NRTI excision. Furthermore, /researchers/ showed that EFV facilitated efficient formation of stable, DEC-like complexes by TFV- or FTC-monophosphate (MP)-terminated DNA and this can contribute to the synergistic inhibition of HIV-1 RT by TFV-diphosphate (DP)+EFV and FTC-TP+EFV combinations. This study demonstrated a clear correlation between the synergistic antiviral activities of TFV+FTC, TFV+EFV, FTC+EFV, and TFV+FTC+EFV combinations and synergistic HIV-1 RT inhibition at the enzymatic level. /Researchers/ propose the molecular mechanisms for the TFV+FTC+EFV synergy to be a combination of increased levels of the active metabolites TFV-DP and FTC-TP and enhanced DEC formation by a chain-terminated DNA and HIV-1 RT in the presence of the second and the third drug in the combination. This study furthers the understanding of the longstanding observations of synergistic anti-HIV-1 effects of many NRTI+NNRTI and certain NRTI+NRTI combinations in cell culture, and provides biochemical evidence that combinations of anti-HIV agents can increase the intracellular drug efficacy, without increasing the extracellular drug concentrations.

---

Drug Warnings
/BOXED WARNING/ WARNING: LACTIC ACIDOSIS/SEVERE HEPATOMEGALY WITH STEATOSIS and POST TREATMENT EXACERBATION OF HEPATITIS. Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogs, including Viread, in combination with other antiretrovirals. Severe acute exacerbations of hepatitis have been reported in HBV-infected patients who have discontinued anti-hepatitis B therapy, including Viread. Hepatic function should be monitored closely with both clinical and laboratory follow-up for at least several months in patients who discontinue anti-hepatitis B therapy, including Viread. If appropriate, resumption of anti-hepatitis B therapy may be warranted.
Lactic acidosis and severe hepatomegaly with steatosis (sometimes fatal) have been reported rarely in patients receiving nucleoside reverse transcriptase inhibitors alone or in conjunction with other antiretroviral agents. Most reported cases have involved women; obesity and long-term therapy with a nucleoside reverse transcriptase inhibitor also may be risk factors. Caution should be observed when nucleoside analogs are used in patients with known risk factors for liver disease; however, lactic acidosis and severe hepatomegaly with steatosis have been reported in patients with no known risk factors. Tenofovir therapy should be interrupted in any patient with clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity (signs of hepatotoxicity include hepatomegaly and steatosis even in the absence of marked increases in serum aminotransferase concentrations).
Redistribution or accumulation of body fat, including central obesity, dorsocervical fat enlargement (buffalo hump), peripheral wasting, facial wasting, breast enlargement, and general cushingoid appearance, has been reported with antiretroviral therapy.
The most common adverse effects in HIV-infected patients receiving tenofovir disoproxil fumarate are rash, diarrhea, headache, pain, depression, asthenia, and nausea. The most common adverse effect in HIV-infected patients receiving tenofovir disoproxil fumarate is nausea.
For more Drug Warnings (Complete) data for TENOFOVIR DISOPROXIL FUMARATE (14 total), please visit the HSDB record page.

C19H30N5O10P.C4H4O4

635.51

635.183

C, 43.47; H, 5.39; N, 11.02; O, 35.24; P, 4.87

202138-50-9

Tenofovir Disoproxil;201341-05-1;Tenofovir;147127-20-6;Tenofovir maleate;1236287-04-9; 201341-05-1 (free); 202138-50-9 (fumarate); 206184-49-8 (hydrate); 379270-37-8 (alafenamide); 1571075-19-8 (aspartate)

6398764

White, fine, powder-like crystals

1.45 g/cm3

642.7ºC at 760 mmHg

219ºC

342.5ºC

2.06E-16mmHg at 25°C

3.328

3

18

19

43

817

1

P(C([H])([H])O[C@]([H])(C([H])([H])[H])C([H])([H])N1C([H])=NC2=C(N([H])[H])N=C([H])N=C12)(=O)(OC([H])([H])OC(=O)OC([H])(C([H])([H])[H])C([H])([H])[H])OC([H])([H])OC(=O)OC([H])(C([H])([H])[H])C([H])([H])[H].O([H])C(C([H])=C([H])C(=O)O[H])=O

VCMJCVGFSROFHV-WZGZYPNHSA-N

InChI=1S/C19H30N5O10P.C4H4O4/c1-12(2)33-18(25)28-9-31-35(27,32-10-29-19(26)34-13(3)4)11-30-14(5)6-24-8-23-15-16(20)21-7-22-17(15)24;5-3(6)1-2-4(7)8/h7-8,12-14H,6,9-11H2,1-5H3,(H2,20,21,22);1-2H,(H,5,6)(H,7,8)/b;2-1+/t14-;/m1./s1

9-((R)-2-((Bis(((isopropoxycarbonyl)oxy)methoxy)phosphinyl)methoxy)propyl)adenine, fumarate

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment, avoid exposure to moisture.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Solubility in Formulation 1: ≥ 2.5 mg/mL (3.93 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

---

Solubility in Formulation 2: ≥ 2.5 mg/mL (3.93 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

---

View More

Solubility in Formulation 3: ≥ 2.5 mg/mL (3.93 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

---

Solubility in Formulation 4: 20 mg/mL (31.47 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication.

---

 (Please use freshly prepared in vivo formulations for optimal results.)