Rifaximin   中文名称: 利福西亚胺

RNA polymerase

体外活性：Rifaximin (50 μM) 可减少 IEC 中由 LPS 刺激引起的促炎因子产生的变化，例如正常肠上皮细胞中的 TNF-α、IL-8、Rantes 和 PGE2。 Rifaximin 通过抑制 NF-κB DNA 结合活性来抑制 LPS 诱导的细胞因子和趋化因子的表达。 Rifaximin (100 μM) 有效降低 LPS 刺激 (100 μg/mL) 诱导的 TNFα、IL-8、MIP-3α 和 Rantes 的表达。利福昔明与细菌 DNA 依赖性 RNA 聚合酶的 β 亚基结合，抑制 RNA 合成中链形成的起始。利福昔明对革兰氏阳性菌的 MIC 较低，剂量范围为 0.01 µg/mL 至 0.5 µg/mL 时的 MIC90。利福昔明对需氧和厌氧革兰氏阳性和革兰氏阴性微生物具有广谱活性。

与利福平相比，利福昔明在肠道中浓度较高。利福昔明治疗导致 hPXR 小鼠肠道中 PXR 靶基因的显着诱导，但在野生型和 Pxr 缺失小鼠中则不然。利福昔明介导的人 PXR 激活，但不介导其他外源性核受体组成型雄甾烷受体、过氧化物酶体增殖物激活受体 (PPAR)α、PPARgamma 和法尼醇 X 受体。由于激活参与脂质摄取的基因，利福昔明可能导致 PXR 依赖性肝细胞脂肪变性，因此表明长期接触利福昔明对肝功能有潜在的不利影响。

细胞系：Caco-2 细胞 浓度：0.1、1.0 和 10.0 μM 孵育时间：48 小时 结果：导致细胞增殖显着且呈浓度依赖性减少。以浓度依赖性方式减少 PCNA 的表达。

Balb/c mice (6–8 weeks old) bearing 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis
10, 30 and 50 mg/kg/day
Orally, p.o. daily for 7 days

Absorption, Distribution and Excretion
Low absorption in both the fasting state and when administered within 30 minutes of a high-fat breakfast.
In a mass balance study, after administration of 400 mg 14C-rifaximin orally to healthy volunteers, of the 96.94% total recovery, 96.62% of the administered radioactivity was recovered in feces almost exclusively as the unchanged drug and 0.32% was recovered in urine mostly as metabolites with 0.03% as the unchanged drug.Rifaximin accounted for 18% of radioactivity in plasma. This suggests that the absorbed rifaximin undergoes metabolism with minimal renal excretion of the unchanged drug

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Metabolism / Metabolites
In vitro drug interactions studies have shown that rifaximin, at concentrations ranging from 2 to 200 ng/mL, did not inhibit human hepatic cytochrome P450 isoenzymes: 1A2, 2A6, 2B6, 2C9, 2C19, 2D6, 2E1, and 3A4. In an in vitro hepa-tocyte induction model, rifaximin was shown to induce cytochrome P450 3A4 (CYP3A4), an isoenzyme which rifampin is known to induce.

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Biological Half-Life
Approximately 6 hours.

Hepatotoxicity
Despite widespread use, there is little evidence that rifaximin when given orally causes liver injury, either in the form of serum enzyme elevations or clinically apparent liver disease.
Likelihood score: E (unlikely cause of clinically apparent liver injury).

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Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
Rifaximin is poorly absorbed orally and used only for gastrointestinal infections. It is not likely to reach the breastmilk or bloodstream of the infant or cause any adverse effects in breastfed infants after maternal use. However, no published experience exists with rifaximin during breastfeeding; therefore, an alternate drug may be preferred, especially while nursing a newborn or preterm infant.
◉ Effects in Breastfed Infants
Relevant published information was not found as of the revision date.
◉ Effects on Lactation and Breastmilk
Relevant published information was not found as of the revision date.

[1]. Eur J Pharmacol . 2011 Oct 1;668(1-2):317-24.

[2]. Clin Infect Dis . 2006 Feb 15;42(4):541-7.

[3]. J Pharmacol Exp Ther . 2007 Jul;322(1):391-8.

[4]. Toxicol Sci . 2012 Oct;129(2):456-68.

Rifaximin is a semisynthetic member of the class of rifamycins and non-systemic gastrointestinal site-specific broad spectrum antibiotic. Used in the treatment of traveller's diarrhoea, hepatic encephalopathy and irritable bowel syndrome. It has a role as a gastrointestinal drug, an orphan drug and an antimicrobial agent. It is a member of rifamycins, an acetate ester, a lactam, an organic heterohexacyclic compound, a macrocycle, a semisynthetic derivative and a cyclic ketal.
Rifaximin is a semisynthetic, rifamycin-based non-systemic antibiotic, meaning that the drug will not pass the gastrointestinal wall into the circulation as is common for other types of orally administered antibiotics. It has multiple indications and is used in treatment of traveller's diarrhea caused by E. coli; reduction in risk of overt hepatic encephalopathy recurrence; as well as diarrhea-predominant irritable bowel syndrome (IBS-D) in adult women and men. It is marketed under the brand name Xifaxan by Salix Pharmaceuticals.
Rifaximin is a Rifamycin Antibacterial.
Rifaximin is a nonabsorbable antibiotic that is used as treatment and prevention of travelers’ diarrhea and, in higher doses, for prevention of hepatic encephalopathy in patients with advanced liver disease and to treat diarrhea in patients with irritable bowel syndrome. Rifaximin has minimal oral absorption and has not been implicated in causing liver test abnormalities or clinically apparent liver injury.
Rifaximin has been reported in Bos taurus with data available.
Rifaximin is an orally administered, semi-synthetic, nonsystemic antibiotic derived from rifamycin SV with antibacterial activity. Rifaximin binds to the beta-subunit of bacterial DNA-dependent RNA polymerase, inhibiting bacterial RNA synthesis and bacterial cell growth. As rifaximin is not well absorbed, its antibacterial activity is largely localized to the gastrointestinal tract.
A synthetic rifamycin derivative and anti-bacterial agent that is used for the treatment of GASTROENTERITIS caused by ESCHERICHIA COLI INFECTIONS. It may also be used in the treatment of HEPATIC ENCEPHALOPATHY.
See also: Cefuzonam Sodium (annotation moved to).

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Drug Indication
Rifaximin has multiple indications by the FDA: for the treatment of patients (≥12 years of age) with traveller's diarrhea caused by noninvasive strains of Escherichia coli; for the reduction of overt hepatic encephalopathy recurrence in patients ≥18 years of age; and in May 2015 it was approved for irritable bowel syndrome with diarrhea (IBS-D) treatment in adult men and women.
FDA Label

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Mechanism of Action
Rifaximin acts by inhibiting RNA synthesis in susceptible bacteria by binding to the beta-subunit of bacterial deoxyribonucleic acid (DNA)-dependent ribonucleic acid (RNA) polymerase enzyme. This binding blocks translocation, which stops transcription.

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Pharmacodynamics
Rifaximin is a structural analog of rifampin and a non-systemic, gastrointestinal site-specific antibiotic. This non-systemic property of the drug is due to the addition of a pyridoimidazole ring, which renders it non-absorbable. Rifaximin acts by inhibiting bacterial ribonucleic acid (RNA) synthesis and contributes to restore intestinal microflora imbalance. Other studies have also shown rifaximin to be an pregnane X receptor (PXR) activator. As PXR is responsible for inhibiting the proinflammatory transcription factor NF-kappa B (NF-κB) and is inhibited in inflammatory bowel disease (IBD), rifaximin was proven to be effective for the treatment of IBS-D.

C43H51N3O11

785.88

785.352

C, 65.72; H, 6.54; N, 5.35; O, 22.39

80621-81-4

6436173

Yellow to orange solid powder

1.4±0.1 g/cm3

200-205ºC(dec)

1.634

3.22

198.38

5

12

3

57

1590

9

CC1=CC(N2C=C1)=NC3=C2C(NC(/C(C)=C\C=C\[C@H](C)[C@H](O)[C@@H](C)[C@@H](O)[C@@H](C)[C@H](OC(C)=O)[C@@H](C)[C@H](OC)/C=C\O[C@@](C4=O)(C)O5)=O)=C(O)C6=C(O)C(C)=C5C4=C63

NZCRJKRKKOLAOJ-XRCRFVBUSA-N

InChI=1S/C43H51N3O11/c1-19-14-16-46-28(18-19)44-32-29-30-37(50)25(7)40-31(29)41(52)43(9,57-40)55-17-15-27(54-10)22(4)39(56-26(8)47)24(6)36(49)23(5)35(48)20(2)12-11-13-21(3)42(53)45-33(34(32)46)38(30)51/h11-18,20,22-24,27,35-36,39,48-51H,1-10H3,(H,45,53)/b12-11+,17-15+,21-13-/t20-,22+,23+,24+,27-,35-,36+,39+,43-/m0/s1

[(7S,9E,11S,12R,13S,14R,15R,16R,17S,18S,19E,21Z)-2,15,17,36-tetrahydroxy-11-methoxy-3,7,12,14,16,18,22,30-octamethyl-6,23-dioxo-8,37-dioxa-24,27,33-triazahexacyclo[23.10.1.14,7.05,35.026,34.027,32]heptatriaconta-1(35),2,4,9,19,21,25(36),26(34),28,30,32-undecaen-13-yl] acetate

BRN-3584528; L-105; BRN 3584528; L105; BRN3584528; L 105SV; Fatroximin; Normix; Rifacol; Rifamycin L 105; Rifaxidin; Rifaximin; Rifaxin; Ritacol; Rifaximin; trade names: RCIFAX, Rifagut; Xifaxan; Zaxine

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

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

配方 1 中的溶解度: ≥ 3 mg/mL (3.82 mM) (饱和度未知) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (这些助溶剂从左到右依次添加，逐一添加), 澄清溶液。
例如，若需制备1 mL的工作液，可将100 μL 30.0 mg/mL 澄清的 DMSO 储备液加入到400 μL PEG300中，混匀；再向上述溶液中加入50 μL Tween-80，混匀；然后加入450 μL 生理盐水定容至1 mL。
*生理盐水的制备：将 0.9 g 氯化钠溶解在 100 mL ddH₂O中，得到澄清溶液。

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配方 2 中的溶解度: ≥ 3 mg/mL (3.82 mM) (饱和度未知) in 10% DMSO + 90% Corn Oil (这些助溶剂从左到右依次添加，逐一添加), 澄清溶液。
例如，若需制备1 mL的工作液，可将 100 μL 30.0 mg/mL 澄清 DMSO 储备液加入900 μL 玉米油中，混合均匀。

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配方 3 中的溶解度: 2.08 mg/mL (2.65 mM) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (这些助溶剂从左到右依次添加，逐一添加), 悬浊液; 超声助溶。
例如，若需制备1 mL的工作液，可将 100 μL 20.8 mg/mL澄清DMSO储备液加入900 μL 20% SBE-β-CD生理盐水溶液中，混匀。
*20% SBE-β-CD 生理盐水溶液的制备（4°C，1 周）：将 2 g SBE-β-CD 溶解于 10 mL 生理盐水中，得到澄清溶液。

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请根据您的实验动物和给药方式选择适当的溶解配方/方案：
1、请先配制澄清的储备液(如：用DMSO配置50 或 100 mg/mL母液(储备液));
2、取适量母液，按从左到右的顺序依次添加助溶剂，澄清后再加入下一助溶剂。以 下列配方为例说明 (注意此配方只用于说明，并不一定代表此产品 的实际溶解配方):
10% DMSO → 40% PEG300 → 5% Tween-80 → 45% ddH2O (或 saline);
假设最终工作液的体积为 1 mL, 浓度为5 mg/mL: 取 100 μL 50 mg/mL 的澄清 DMSO 储备液加到 400 μL PEG300 中，混合均匀/澄清；向上述体系中加入50 μL Tween-80，混合均匀/澄清；然后继续加入450 μL ddH2O (或 saline)定容至 1 mL；
3、溶剂前显示的百分比是指该溶剂在最终溶液/工作液中的体积所占比例;
4、 如产品在配制过程中出现沉淀/析出，可通过加热(≤50℃)或超声的方式助溶;
5、为保证最佳实验结果，工作液请现配现用！
6、如不确定怎么将母液配置成体内动物实验的工作液，请查看说明书或联系我们;
7、 以上所有助溶剂都可在 Invivochem.cn网站购买。