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|Emtricitabine Chemical Properties|
|Emtricitabine Usage And Synthesis|
|New anti-HIV drugs||Emtricitabine was a novel nucleoside reverse transcriptase inhibitor successfully developed by US Company Gilead Siences, belonging to an anti-viral drugs and exhibits antiviral activity on HIV-1, HIV-2 and HBV. Its antiviral activity exhibits that it can specifically anti-HIV-1, HIV-2 and HBV while even with its drug concentration being raised to 100 mmol / L, it still exhibit no activity against HSV-1, HSV- 2, HCMV, VZV, corona, yellow fever virus, respiratory syncytial virus, Rota, and influenza virus or rhinovirus. Even at a concentration lower than micromolar, the drug still exhibits potent inhibitor effect against the LAV strain and IIIB 1 of HIV virus and the ROD2 strain and ZY virus strain of HIV-2 with an IC50 value lower being 95 times lower than that of AZT (zidovudine). |
It has been increasingly become the focus of the assessment of new drugs that whether new anti-HIV drug will produce cross-resistance to other kinds of antiviral resistant strains such as AZT, etc. The cross-resistance test of emtricitabine against AZT-resistant strains has demonstrated that although IC50 values for these resistant strains have been increased slightly, all kinds of virus strains are still relatively sensitive to emtricitabine. Instead, emtricitabine-resistant viral strains will exhibit significant cross-resistance to antiviral 3TC (lamivudine), but are still sensitive to AZT. Studies have shown that the drug can be used together with AZT with synergistic effect.
Emtricitabine exhibited strong antiviral activity in HBV generating cell lines HepG22.2.15 (PSA subspecies). It can dose-dependently reduce the number of extracellular and intracellular HBVDNA with the IC50 value being 10nmol/L; this value was comparable to another kind of HBV replication inhibitor 3TC. Interferon α nl (Wellferon), α 2a (Ro feron), α 2b (Intron A) can all the production of inhibit HBV viral particles and the accumulation of the intracellular replication virus in the chronic producing cells intracellular production. Combination of them associated with emtricitabine can produce a synergistic effect.
The in vivo anti-hepatitis activity of emtricitabine is investigated through the anti-HBV action in a kind of chimeric mouse model as well as the action of anti-woodchuck hepatitis virus (WHV) function in natural infected prairie dogs. In the mouse model, use different doses for oral administration of this drug to mouse of immune deficiency and carrying human tumors as well as producing human HBV, with the antibody capture / PcR experiment, it was found that the blood HBVDNA (Dane particle) was reduced in a dose-dependent manner with even a low dose of 3.5 mg/(kg • d) also being able to produce significant inhibition while the level of intracellular replicated HBVDNA also exhibited a dose-dependent decrease; however, even at the highest dose (89 mg / (kg • d )), the tumor size remained unchanged, suggesting that the drug has selective anti-HBV activity.
The above information is edited by the Chemicalbook of Dai Xiongfeng.
|Pharmacological effects||Emtricitabine belongs to chemically synthesized nucleoside cytosine. Its mechanism of anti-HIV-1 is through multi-step in vivo phosphorylation generating active triphosphate which competitively inhibits the HIV-1 reverse transcriptase while competing with natural 5-phosphate cytosine by for penetrating into the viral DNA synthesis process, which ultimately leads to the synthesis of a DNA strand break. Its mechanism of HBV is because that the HBV replication process contains target site of emtricitabine, namely reverse transcription process. It has a low inhibitory effect on mammal DNA polymerases α, β, ε and mitochondrial DNA polymerase γ. |
In vitro antiviral activity: in vitro laboratory used and clinical isolate anti-HIV viruses have been assessed in lymphoblastoid cell lines, MAGI-CCR5 cell line, and peripheral blood mononuclear cells. The 50% inhibitory concentration (IC50) value is in the range of 0.0013 ~ 0.158 μg/mL. In the combination study with nucleoside reverse transcriptase inhibitors (NRTI), non-nucleoside reverse transcriptase inhibitor (NNRTI) and protease inhibitors (PI), it exhibited a synergistic effect. Most kinds of combined clinical study have not been carried out. In vitro tests have demonstrated that it has antiviral activity against HIV-1 (A, C, D, E, F and G subtypes) (IC50 values in the range of 0.007 ~ 0.075 μg/mL) while displaying specific inhibition activity against the HIV-2 type (IC50 values in the range of 0.007 ~ 1.5 μg / mL).
|Pharmacokinetics||Pharmacokinetic assessment was performed in healthy volunteers and HIV-infected individuals. The pharmacokinetics of the two groups is similar with each other. |
Absorption: oral administration gives rapid absorption with the drug being widely distributed. After administration of 1 to 2 hours, the plasma concentration reaches peak. 20 cases of HIV infected patients were subject to multiple fold doses of drugs through oral administration (mean ± SD) the plasma concentration peak of emtricitabine (Cmax) is 1.8 ± 0.7μg / mL. At 24 hours, the plasma drug concentration-time area under the curve (AUC) is 10.0 ± 3.1 (h • μg) / mL. At 24h hours after administration, the average steady-state plasma concentration is 0.09μg / mL. The average bioavailability is 93%. At multiple folds of doses, the pharmacokinetics is in proportion with the dose (25 ~ 200mg).
Distribution: In vitro binding rate of emtricitabine to human plasma proteins is < 4%; when the concentration exceeds the range of 0.02 ~ 200 μg/mL, it exists in its free state. At the time of peak concentration, the ratio of plasma drug concentration and blood drug concentration is 1.0, and the ratio of the seminal fluid concentration and plasma drug concentration is 4.0.
Metabolism: In vitro studies have shown that emtricitabine is not an inhibitor of human CYP450 enzymes. Taking 14C-labeled emtricitabine with the prototype reaching the urine (86%) and it (14%). 13% of the dose is converted into three metabolites. The biotransformation substances include the oxidized sulfur portion for generating 3'-sulfoxide diastereomers (9%), and binding to glucuronide for formation of 2'-oxy-glucuronide (4%). Other metabolites have not been determined.
Excretion: The half life of the emtricitabine plasma concentration is about 10 hours. The renal clearance rate of emtricitabine is higher than the creatinine clearance rate, suggesting that it is excreted through glomerular filtration and tubular secretion, and there may be substance competing with it for the kidneys.
|Indications||1. Emtricitabine is combined with other antiviral drugs for treating adult HIV-1 infection. Patients should be those who haven’t been subject to treatment by reverse transcriptase inhibitors or those who have received reverse transcriptase inhibitors with virus having been suppressed. |
2. It can be used for the treatment of chronic hepatitis B.
|Adverse reactions||In the clinical applications, for patients who are subject to emtricitabine and other antiviral drugs, the most common adverse reactions include headache, diarrhea, nausea and rash with the extent from being mild to moderate to severe. About 1% of patients discontinued medication due to the above reasons. The frequency of all kinds of adverse reactions is comparable with the control group quite but with the skin pigmentation being slightly higher in the emtricitabine group. Skin pigmentation usually significantly appears in the palm/foot, being generally mild and not accompanied by other symptoms. The clinical significance and the mechanism are not clear.
|Precautions||This product is mainly excreted by the kidneys, so patients with renal insufficiency should reduce the administered amount upon taking this drug. |
Pregnant women, when taking emtricitabine, may get an adverse effect on the fetus and newborn. This product can also be secreted through breast milk which may also affect the infant. Therefore, it is generally not recommended for pregnant and lactating women to use this product unless in situation of considering save the mother's life.
It has not been established of the children's safety basis. Therefore, it is not recommended for children. Elderly should be cautious when choosing the dose. They can apply appropriate reduction on the dose according to the actual conditions of liver, kidney, heart function decline, associated diseases and the effects of other kinds of drugs.
The impact of excessive drugs is unknown, if there is drug overdose, monitoring should be carried out. Apply maintenance dose treatment when necessary.
|Uses||It is white, white-like powder or crystalline powder Application: treatment of chronic hepatitis B; It has a strong antiviral activity with the safety and tolerance being good.
|Chemical Properties||White to Off-White Crystalline Solid|
|Usage||A reverse transcriptase inhibitor. A nucleoside analog structurally related too lamivudine|
|Usage||A reverse transcriptase inhibitor. It is an effective antiviral agent against HIV, HBV, and other viruses replicating in a similar manner. A nucleoside analog structurally related to Lamivudine (L172500).|
|Usage||Labeled Emtricitabine, intended for use as an internal standard for the quantification of Emtricitabine by GC- or LC-mass spectrometry.|
|Emtricitabine Preparation Products And Raw materials|