anti-HBV, HepG2 cell(EC50=3.75 nM)
The target of Entecavir (SQ 34676) is the DNA polymerase (HBV Pol) of hepatitis B virus (HBV), including wild-type HBV Pol and lamivudine (3TC)-resistant HBV Pol mutants (YMDD mutants: M550V/L526M, M550I). Entecavir triphosphate (ETV-TP) is 100- to 300-fold more potent than 3TC-TP against 3TC-resistant HBV Pol, and 20- to 30-fold higher concentrations of Entecavir are required to inhibit the replication of 3TC-resistant HBV in cell culture [1]

Entecavir-triphosphate is a highly potent inhibitor of wild-type HBV Pol and is 100- to 300-fold more potent than lamivudine-triphosphate against 3TC-resistant HBV Pol. Entecavir inhibits the replication of 3TC-resistant HBV, but 20- to 30-fold higher concentrations are required. Entecavir results in an impressive reduction of serum viral DNA with covalently closed circular DNA and hepatitis B viral core antigen negativity in liver biopsy specimens. Entecavir has potent activity (EC50, 0.1 nM) against HIV in a unique single-cycle, single-cell-based pseudovirus assay (24) with CD4+ lymphocytes using a green fluorescent protein reporter fluorescence-activated cell sorter assay as the endpoint.

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1. Enzyme activity level: Entecavir triphosphate (ETV-TP) is a highly potent inhibitor of wild-type HBV Pol, and its inhibitory activity against 3TC-resistant HBV Pol (YMDD mutants: M550V/L526M, M550I) is 100- to 300-fold higher than that of 3TC-TP [1]
2. Cell activity level: Entecavir can inhibit the replication of 3TC-resistant HBV in HepG2 cells, but the required concentration is 20- to 30-fold higher than that for wild-type HBV [1]
3. Intracellular phosphorylation: In hepatoma cells treated with extracellular Entecavir concentrations representative of plasma drug levels in patients, intracellular ETV-TP accumulates to levels sufficient to inhibit the enzyme activity of both wild-type and 3TC-resistant HBV Pol [1]

Entecavir causes a 4-log drop in serum DHBV DNA levels within 80 days and a slower 2- to 3-log drop in serum DHBV surface antigen (DHBsAg) levels within 120 days in ducks. Entecavir treatment reduces DHBV DNA replicative intermediates 70-fold in the liver, while the level of the stable, template form, covalently closed circular DNA decreases only 4-fold in ducks. Entecavir treatment reduces both the intensity of antigen staining and the percentage of antigen-positive hepatocytes in the liver, but the intensity of antigen staining in bile duct cells appeares not to be effected in ducks. Daily oral treatment with BMS-200475 at doses ranging from 0.02 to 0.5 mg/kg of body weight for 1 to 3 months effectively reduces the level of woodchuck hepatitis virus (WHV) viremia in chronically infected woodchucks

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1. In ducks with persistent duck hepatitis B virus (DHBV) infection, oral administration of Entecavir at a dose of 0.1 mg/kg of body weight per day for 244 days caused a 4-log reduction in serum DHBV DNA levels within 80 days and a 2- to 3-log reduction in serum DHBV surface antigen (DHBsAg) levels within 120 days [2]
2. After withdrawal of Entecavir treatment in DHBV-infected ducks, serum DHBV DNA and DHBsAg levels rebounded to the levels of water-treated ducks within 40 days [2]
3. Entecavir treatment reduced DHBV DNA replicative intermediates in duck liver by 70-fold, while the level of covalently closed circular DNA (cccDNA) (the stable template form) only decreased by 4-fold [2]
4. Entecavir treatment reduced the intensity of antigen staining and the percentage of antigen-positive hepatocytes in the duck liver, but the intensity of antigen staining in bile duct cells was not affected [2]
5. Intramuscular administration of five doses of DHBV DNA vaccine (expressing presurface, surface, precore, and core antigens) either alone or in combination with Entecavir treatment did not produce a significant effect on viral markers in DHBV-infected ducks [2]

BMS-200475 has a EC50 of 3.75 nM against HBV. It is incorporated into the protein primer of HBV and subsequently inhibits the priming step of the reverse transcriptase. The antiviral activity of BMS-200475 is significantly less against the other RNA and DNA viruses. Entecavir is more readily phosphorylated to its active metabolites than other deoxyguanosine analogs (penciclovir, ganciclovir, lobucavir, and aciclovir) or lamivudine. The intracellular half-life of entecavir is 15 h.

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1. Preparation of recombinant HBV nucleocapsids containing wild-type or 3TC-resistant HBV Pol (YMDD mutants: M550V/L526M, M550I) [1]
2. Incubation of the recombinant HBV nucleocapsids with different concentrations of ETV-TP or 3TC-TP to measure the inhibitory effect on HBV Pol activity [1]
3. Calculation of inhibition curves using a four-parameter logistic equation to determine the IC₅₀ values of ETV-TP and 3TC-TP for wild-type and mutant HBV Pol, and comparison of their inhibitory potencies [1]

BMS 200475 is prepared in phosphate-buffered saline (PBS) and diluted with appropriate medium containing 2% fetal bovine serum. HepG2 2.2.15 cells are plated at a density of 5×105 cells per well on 12-well Biocoat collagen-coated plates and are maintained in a confluent state for 2 to 3 days before being overlaid with 1 mL of medium spiked with BMS 200475. Quantification of HBV was performed on day 10.

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1. Assay for wild-type HBV replication: HepG2 cells were infected with wild-type BAC-HBV at a multiplicity of infection (MOI) of 100 for 3 hours, then washed and incubated in RPMI 1640 medium containing 5% fetal calf serum (FCS) with different concentrations of Entecavir or lamivudine. Culture supernatants were sampled at different time points, and HBV DNA was analyzed by DNA dot blot hybridization to evaluate the inhibitory effect of the drugs [1]
2. Assay for 3TC-resistant HBV replication: HepG2 cells were transfected with plasmids encoding 3TC-resistant HBV (pCMV-M550V/L526M or pCMV-M550I). Four hours after transfection, the cells were washed and fed with RPMI 1640 medium plus 5% FCS containing different concentrations of Entecavir or lamivudine. On day 6 post-transfection, culture supernatants were analyzed by DNA dot blot hybridization to detect HBV DNA levels [1]
3. Assay for intracellular ETV-TP accumulation: HepG2 cells were treated with ^{3}H-labeled Entecavir (13.9 Ci/mmol) at concentrations of 0.2, 1.0, and 5.0 nM, and the kinetics of intracellular ETV-TP accumulation was measured to assess the phosphorylation efficiency of Entecavir in hepatoma cells [1]

0.02 to 0.5 mg/kg; oral
Ducks and Wookchucks This study was designed to test the efficacy of antiviral treatment with entecavir (ETV) in combination with DNA vaccines expressing duck hepatitis B virus (DHBV) antigens as a therapy for persistent DHBV infection in ducks. Ducks were inoculated with 10(9) DHBV genomes at 7 days of age, leading to widespread infection of the liver and viremia within 7 days, and were then treated orally with either ETV (0.1 mg/kg of body weight/day) or distilled water from 21 days posthatch for 244 days. Treatment with ETV caused a 4-log drop in serum DHBV DNA levels within 80 days and a slower 2- to 3-log drop in serum DHBV surface antigen (DHBsAg) levels within 120 days. Following withdrawal of ETV, levels of serum DHBV DNA and DHBsAg rebounded to match those in the water-treated animals within 40 days. Sequential liver biopsy samples collected throughout the study showed that ETV treatment reduced DHBV DNA replicative intermediates 70-fold in the liver, while the level of the stable, template form, covalently closed circular DNA decreased only 4-fold. ETV treatment reduced both the intensity of antigen staining and the percentage of antigen-positive hepatocytes in the liver, but the intensity of antigen staining in bile duct cells appeared not to be effected. Intramuscular administration of five doses of a DNA vaccine expressing the DHBV presurface, surface, precore, and core antigens, both alone and concurrently with ETV treatment, on days 50, 64, 78, 127, and 141 did not result in any significant effect on viral markers.[2]
Drug administration. Ducks from groups 1 and 2 were weighed three times a week, and ETV at a dose of 0.1 mg/kg/day was administered by gavage to these ducks each day for 244 days. Control ducks (groups 3, 4, and 5) were weighed weekly and given 2 ml of distilled water by gavage daily.[2]

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1. Establishment of persistent DHBV infection model: Ducks were inoculated with 10⁹ DHBV genomes at 7 days of age, leading to widespread liver infection and viremia within 7 days [2]
2. Drug administration: Starting from 21 days post-hatch, ducks were treated orally with Entecavir at a dose of 0.1 mg/kg of body weight per day or distilled water for 244 days [2]
3. DNA vaccination: Intramuscular administration of five doses of DHBV DNA vaccine (expressing DHBV presurface, surface, precore, and core antigens) or empty DNA vector on days 50, 64, 78, 127, and 141 post-hatch, either alone or in combination with Entecavir treatment [2]
4. Sample collection and detection: Surgical liver biopsies were performed on days 18, 42, 91, and 181 post-hatch; two ducks from each treatment group were autopsied on day 243 (the day before drug withdrawal), and the remaining ducks were biopsied on day 287 and autopsied on day 298 or 320. Serum DHBV DNA was detected by real-time PCR, serum DHBsAg was quantified by ELISA, and liver tissue was analyzed for total DHBV DNA and cccDNA by Southern blot hybridization; immunoperoxidase staining was used to detect DHBsAg-positive cells in the liver [2]

Absorption, Distribution and Excretion
Absorption: In healthy subjects, peak plasma concentrations of entecavir occurred between 0.5 and 1.5 hours after oral administration. In healthy subjects, the bioavailability of the tablets relative to the oral solution was 100%.
Renal clearance = 383.2 ± 101.8 mL/min [Normal renal function]
Renal clearance = 197.9 ± 78.1 mL/min [Mild renal impairment]
Renal clearance = 135.6 ± 31.6 mL/min [Moderate renal impairment]
Renal clearance = 40.3 ± 10.1 mL/min [Severe renal impairment]
Apparent oral clearance = 588.1 ± 153.7 mL/min [Normal renal function]
Apparent oral clearance = 309.2 ± 62.6 mL/min [Mild renal impairment]
Apparent oral clearance = 226.3 ± 60.1 mL/min [Moderate renal impairment]
Apparent oral clearance = 100.6 ± 29.1 mL/min [Severe renal impairment]
Apparent oral clearance = 50.6 ± 16.5 mL/min [Severe renal impairment, treated with hemodialysis]
Apparent oral clearance = 35.7 ± 19.6 mL/min [Severe renal impairment, treated with peritoneal dialysis]
The bioavailability of entecavir tablets is comparable to that of oral solutions.
Oral administration of 0.5 mg entecavir with a standard high-fat meal results in delayed absorption (1–1.5 hours postprandial, 0.75 hours fasting), a 44%–46% decrease in Cmax, and a 18%–20% decrease in AUC.
The estimated apparent volume of distribution exceeds that of entecavir, which is mainly distributed throughout the body. In vitro studies have shown that entecavir has a low binding rate to human serum proteins (13%). For more complete data on the absorption, distribution, and excretion of entecavir (7 types), please visit the HSDB record page. Metabolites/Metabolites: Entecavir is not a substrate, inhibitor, or inducer of the cytochrome P450 (CYP450) enzyme system. Entecavir is efficiently phosphorylated to its active triphosphate form. No oxidative or acetylated metabolites were observed after administration of 14C-entecavir. Small amounts of phase II metabolites (glucuronide and sulfate conjugates) were observed. Entecavir is not a substrate, inhibitor, or inducer of the cytochrome P450 enzyme system. Biological Half-Life: After reaching peak concentration, entecavir plasma concentrations exhibit a biexponential decline, with a terminal elimination half-life of approximately 128–149 hours. The half-life of the phosphorylated metabolite is 15 hours. The elimination half-life is approximately 128–149 hours. The accumulation half-life is 24 hours.

Hepatotoxicity
In patients with chronic hepatitis B receiving entecavir, 2% to 10% experience elevated serum ALT levels. These elevations appear to be due to transient relapses of underlying chronic hepatitis B and occur both during and after treatment. During treatment, ALT elevations typically occur in the first 1 to 2 months, are mild, asymptomatic, and self-limiting, and are accompanied by a rapid decline in HBV DNA levels. In patients with hepatitis B receiving entecavir, 8% to 12% experience post-discontinuation ALT elevations. Post-discontinuation ALT elevations usually occur within 1 to 3 months after discontinuation and typically precede a significant and abrupt increase in HBV DNA levels to near pre-treatment levels. Severe and critical relapses of hepatitis B after discontinuation can occur, with several cases of acute liver failure reported in patients who discontinued entecavir treatment 1 to 3 years prior. Because most patients continue entecavir treatment, reports of post-discontinuation relapses are less common. However, the incidence and severity of relapse after discontinuation of entecavir may be similar to those of relapse after discontinuation of other hepatitis B treatments. Lactic acidosis has been reported in patients with advanced hepatitis B treated with entecavir; however, lactate levels have been normal in cirrhotic patients treated with entecavir and prospectively followed, and no cases of lactic acidosis have been reported in large clinical trials. Cases of lactic acidosis attributable to entecavir mainly occur in patients with severe, advanced disease, and may be due to sepsis, hypotension, and/or liver failure, rather than adverse reactions to entecavir. Entecavir treatment is not associated with the occurrence of typical syndromes (such as lactic acidosis, hepatic steatosis, and liver failure) in patients without a prior history of severe liver disease, syndromes that have been reported with stavudine, didanosin, and zidovudine. Therefore, clinically significant direct hepatotoxicity caused by entecavir, even if it occurs, is certainly very rare.
Probability Score: E (Suspected but unconfirmed clinically significant cause of liver injury).

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Use during pregnancy and lactation
◉ Overview of use during lactation
No studies have been conducted on entecavir in breastfeeding women receiving treatment for hepatitis B virus infection. Especially in breastfeeding newborns or premature infants, alternative medications may be necessary.
As long as the infant receives hepatitis B immunoglobulin and hepatitis B vaccine at birth, there is no difference in infection rates between breastfed and formula-fed infants born to mothers with hepatitis B infection. Mothers with hepatitis B are encouraged to breastfeed after their infants have received these precautions.
◉ Effects on breastfed infants
No relevant published information found as of the revision date.
◉ Effects on lactation and breast milk
No relevant published information found as of the revision date.

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Protein binding
The in vitro binding rate of entecavir to human serum proteins is approximately 13%.

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Interactions
Pharmacokinetic interactions may occur with drugs that reduce renal function or may compete with entecavir for active tubular secretion; serum concentrations of entecavir or concomitant drugs may be elevated. Although the effects of concomitant use of such drugs with entecavir have not been specifically studied, patients receiving entecavir who are also taking other drugs that may affect renal function or be excreted by the kidneys should be closely monitored for adverse reactions. In vitro evidence suggests that concomitant use of nucleoside reverse transcriptase inhibitors (NRTIs) with entecavir is unlikely to reduce the antiviral efficacy of entecavir against hepatitis B virus (HBV) or reduce the antiretroviral activity of NRTIs (such as abacavir, didanosin, lamivudine, stavudine, tenofovir disoproxil fumarate, or zidovudine) against HIV. Pharmacokinetic interactions may occur with cyclosporine or tacrolimus (due to changes in renal function leading to elevated serum concentrations of entecavir). For patients receiving cyclosporine, tacrolimus, or other immunosuppressants that may affect renal function (such as transplant recipients), renal function should be monitored before and during entecavir treatment.

[1]. Antimicrob Agents Chemother.2002 Aug;46(8):2525-32.

[2]. Antimicrob Agents Chemother.2003 Aug;47(8):2624-35.

[3]. Antimicrob Agents Chemother. 1997 Jul;41(7):1444-9.

[4]. Curr Med Res Opin.?2005 Nov;21(11):1845-57.

[5]. Antimicrob Agents Chemother.?1998 Dec;42(12):3209-18.

Therapeutic Uses
Antiviral Drug
Entecavir has been evaluated for its efficacy in treating chronic hepatitis B virus (HBV) infection in a phase III randomized, double-blind, active-controlled study (AI463038). The study enrolled HIV-infected patients receiving highly active antiretroviral therapy (HAART, including lamivudine). These patients had relapsed HBV viremia (99% HBeAg positive), active HBV replication (median baseline serum HBV DNA level of 9.13 log10 copies/mL), and persistently elevated serum alanine aminotransferase (ALT) levels (mean serum ALT of 71.5 IU/L). Patients continued HAART (including 300 mg lamivudine daily) and were randomized to receive either entecavir (1 mg daily) or placebo for 24 weeks, followed by a 24-week open-label period during which all patients received entecavir (1 mg daily). Analysis of limited data at week 24 showed that 6% of patients receiving entecavir plus lamivudine HAART had serum HBV DNA levels below the detection limit (defined as below 300 copies/mL by PCR), compared to 0% in patients receiving placebo plus lamivudine HAART. Among patients receiving entecavir-containing regimens, 34% had normal serum ALT levels (i.e., a biochemical response) at week 24, compared to 8% in patients not receiving entecavir. Furthermore, patients receiving entecavir-containing regimens showed a mean decrease in serum HBV DNA levels of 3.65 log10 copies/mL from baseline at week 24, compared to a mean increase of 0.11 log10 copies/mL in patients receiving lamivudine HAART alone. During the 24-week double-blind study, median serum HIV-1 RNA levels remained stable at approximately 2 log10/mL. Entecavir was evaluated in a phase III randomized, double-blind, active-controlled study (AI463026) for the treatment of lamivudine-refractory chronic hepatitis B virus (HBV) infection. The study included adult patients with active HBV replication (median baseline serum HBV DNA level of 9.36 log10 copies/mL), persistently elevated serum ALT levels (mean serum ALT of 128 IU/L), and histological evidence of active liver disease (mean Knodell necrotizing inflammation score of 6.5). In the study, 76% of patients were male, 37% were Asian, 62% were Caucasian, and 52% had previously received interferon-alpha therapy. The median duration of prior lamivudine treatment in this study was 2.7 years, and 85% of patients had lamivudine resistance mutations at baseline. Patients were randomly assigned to two groups: one group switched from lamivudine to entecavir (1 mg daily), and the other group continued receiving lamivudine (100 mg daily) for 52 weeks (without washout or overlap periods). Data analysis at week 48 showed that 55% of patients switching to entecavir experienced histological improvement (defined as a decrease of at least 2 points in the Knodell necrosis-inflammation score without simultaneous worsening of the Knodell fibrosis score), compared to only 28% of patients continuing lamivudine. At week 48, 61% of patients receiving entecavir achieved normal serum ALT levels (i.e., a biochemical response), compared to only 15% of patients receiving lamivudine. Furthermore, at week 48, patients receiving entecavir showed a mean decrease of 5.11 log10 copies/mL from baseline in serum HBV DNA levels, compared to only a decrease of 0.48 log10 copies/mL in patients receiving lamivudine. In patients treated with entecavir, 19% had undetectable serum HBV DNA levels at week 48 (defined as less than 300 copies/mL by PCR), compared to only 1% in patients treated with lamivudine. Anti-HBe seroconversion occurred in 8% of patients treated with entecavir, compared to only 3% in patients treated with lamivudine. Approximately 55% of patients treated with entecavir continued treatment for up to 96 weeks. Of these patients, 40% had undetectable serum HBV DNA levels, 81% had normal ALT levels, and 10% achieved seroconversion. A phase III randomized, double-blind, active-controlled study (AI463027) evaluated the efficacy of entecavir in treating chronic HBV infection in HBeAg-negative, anti-HBe, and HBV-DNA-positive patients. The study included adult patients who had not received nucleoside analogue therapy, had active HBV replication (median baseline serum HBV DNA level of 7.58 log10 copies/mL, detected by PCR), persistently elevated serum ALT levels (mean serum ALT of 142 IU/L), and histological evidence of active liver disease (mean Knodell necrotizing inflammation score of 7.8). In this study, 76% of patients were male, 58% were Caucasian, 39% were Asian, and 13% had previously received interferon-alpha therapy. Analysis of data over 48 weeks showed that 70% of patients treated with entecavir (0.5 mg daily) experienced histological improvement (defined as a decrease in Knodell necrotizing inflammation score of at least 2 points without simultaneous worsening of Knodell fibrosis score), compared to 61% of patients treated with lamivudine (100 mg daily). Furthermore, in patients treated with entecavir, 78% had their serum ALT levels return to normal by week 48, compared to 71% in patients treated with lamivudine. Additionally, patients receiving entecavir 0.5 mg daily showed a mean decrease of 5.04 log10 copies/mL in serum HBV DNA levels from baseline at week 48, compared to a mean decrease of 4.53 log10 copies/mL in patients receiving lamivudine 100 mg daily. In patients treated with entecavir, 90% had undetectable serum HBV DNA levels at week 48 (defined as below 300 copies/mL by PCR), compared to 72% in patients treated with lamivudine. Of the patients treated with entecavir, 85% met the response criteria (determined by HBV virological suppression [bDNA detection below 0.7 MEq/mL] and HBeAg disappearance at week 48) and discontinued entecavir as scheduled at week 52; only a very small number of these patients had undetectable serum HBV DNA levels, and 46% of patients maintained normal ALT concentrations during the subsequent 24-week follow-up. For more complete data on the therapeutic uses of entecavir (6 types), please visit the HSDB record page. Drug Warnings The optimal duration of entecavir treatment for patients with chronic hepatitis B and the relationship between treatment and long-term outcomes (such as cirrhosis and hepatocellular carcinoma) are not yet clear. Severe acute exacerbations of hepatitis B have occurred after discontinuation of hepatitis B virus (HBV) treatment (including entecavir treatment). In studies evaluating the safety of entecavir, hepatitis exacerbation or ALT elevation was defined as an ALT elevation exceeding 10 times the upper limit of normal (ULN) and exceeding 2 times the baseline serum concentration. In clinical studies (AI463022, AI463027, AI463026), ALT elevations occurred in 2%, 8%, and 12% of nucleoside analog-naïve HBeAg-positive, nucleoside analog-naïve HBeAg-negative, or lamivudine-refractory patients, respectively, after discontinuation of entecavir. The median time to hepatitis exacerbation was 23 weeks. The incidence of post-treatment ALT elevation may be even higher if entecavir is discontinued regardless of prior treatment response.
FDA Pregnancy Category C; risk cannot be ruled out. Currently, adequate, well-controlled clinical studies are lacking, and animal studies have either not shown any risk to the fetus or lack relevant data. Use of this drug during pregnancy may cause harm to the fetus; however, the potential benefits may outweigh the potential risks. It is unclear whether entecavir is excreted into breast milk. Considering the importance of the drug to the woman, breastfeeding should be discontinued or the drug discontinued. For more complete data on drug warnings for entecavir (15 in total), please visit the HSDB records page.

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Pharmacodynamics
Entecavir is a guanosine nucleoside analog with selective activity against hepatitis B virus (HBV). It is designed to selectively inhibit HBV, blocking all three steps of its replication process. Entecavir is more effective than an older hepatitis B drug, lamivudine. 1. Entecavir (SQ 34676) is a potent and selective HBV replication inhibitor that is effective both in vitro and in vivo, and is currently undergoing clinical trials for the treatment of chronic HBV infection.[1] 2. Lamivudine (3TC) is currently the only antiviral drug for hepatitis B virus (HBV), but its main limitation is that most patients treated develop drug-resistant HBV due to specific mutations in the HBV polymerase (Pol) nucleotide binding site.[1] 3. The persistent presence of covalently closed circular DNA (cccDNA) in the liver is a key obstacle to eradicating HBV infection, as entecavir, while significantly inhibiting viral replication, only slightly reduces cccDNA levels.[2] 4. Entecavir combined with DHBV DNA vaccine did not enhance the antiviral effect of persistent DHBV infection, suggesting that immunotherapy may need to be optimized to achieve synergistic effects with antiviral drugs.[2]

C12H15N5O3

277.28

277.117

C, 51.98; H, 5.45; N, 25.26; O, 17.31

142217-69-4

Entecavir monohydrate;209216-23-9;Entecavir-13C2,15N;(1R,3S,4R)-ent-Entecavir;188399-46-4;Entecavir-d2

135398508

White to off-white solid powder

1.8±0.1 g/cm3

734.2ºC at 760 mmHg

249-252ºC

397.9ºC

1.837

-0.96

4

5

2

20

480

3

O([H])[C@@]1([H])C([H])([H])[C@@]([H])(C(=C([H])[H])[C@]1([H])C([H])([H])O[H])N1C([H])=NC2C(N([H])C(N([H])[H])=NC1=2)=O

QDGZDCVAUDNJFG-FXQIFTODSA-N

InChI=1S/C12H15N5O3/c1-5-6(3-18)8(19)2-7(5)17-4-14-9-10(17)15-12(13)16-11(9)20/h4,6-8,18-19H,1-3H2,(H3,13,15,16,20)/t6-,7-,8-/m0/s1

2-amino-9-[(1S,3R,4S)-4-hydroxy-3-(hydroxymethyl)-2-methylidenecyclopentyl]-3H-purin-6-one

Entecavir; Baraclude; BMS-200475; BMS-200475; BMS-200475; FT-0083013; FT0083013; FT0083013; D07896; SQ 34676; SQ-34676; SQ34676;

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 (e.g. under nitrogen), 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)

DMSO : ≥ 44~55 mg/mL (158.68~198.35 mM)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*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.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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