Xifaxan
Xifaxan - General Information
Xifaxan 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 is used to treat diarrhea caused by E. coli.
Pharmacology of Xifaxan
Xifaxan is a structural analog of rifampin and non-systemic, gastrointestinal site-specific antibiotic. Xifaxan acts by inhibiting bacterial ribonucleic acid (RNA) synthesis. While an increase in pulmonary hydrogen excretion is evident in diverticular disease, the therapeutic effect of rifaximin does not appear to be due to a persistent correction of this alteration and the drug appears to cause no significant imbalance in the intestinal ecosystem.
Xifaxan for patients
Patients should be advised that XIFAXAN™ Tablets may be taken with or without food. Patients should be advised that XIFAXAN™ Tablets should be discontinued if their diarrhea persists more than 24-48 hours or worsens, or if they have fever and/or blood in the stool that they should seek medical care.
Xifaxan Interactions
Drug-Drug Interactions
Although in vitro studies demonstrated the potential of rifaximin to interact with cytochrome P450 3A4 (CYP3A4), a clinical drug-drug interaction study demonstrated that rifaximin did not significantly affect the pharmacokinetics of midazolam either presystemically or systemically. An additional clinical drug-drug interaction study showed no effect of rifaximin on the presystemic metabolism of an oral contraceptive containing ethinyl estradiol and norgestimate. Therefore, clinical interactions with drugs metabolized by human cytochrome P450 isoenzymes are not expected.
Xifaxan Contraindications
XIFAXAN™ Tablets are contraindicated in patients with a hypersensitivity to rifaximin, any of the rifamycin antimicrobial agents, or any of the components in XIFAXAN™ Tablets.
Additional information about Xifaxan
Xifaxan Indication: For the treatment of patients (>=12 years of age) with travelers' diarrhea caused by noninvasive strains of Escherichia coli.
Mechanism Of Action: Xifaxan is a product of synthesis of rifamycin, an antibiotic with low gastrointestinal absorption and good antibacterial activity (Marchi et al, 1985). It acts on the beta-subunit of the deoxyribonucleic acid (DNA)-dependent ribonucleic acid (RNA) polymerase enzyme of microorganisms to inhibit RNA synthesis.
Drug Interactions: Not Available
Food Interactions: Not Available
Generic Name: Rifaximin
Synonyms: Rifaximin [USAN-INN]; Rifaximina [Spanish]; Rifaximine [French]; Rifaximinum [Latin]; Rifamycin L 105; Rifamycin L 105SV; Rifamixin; Rifaxidin
Drug Category: Anti-Infective Agents; Gastrointestinal Agents
Drug Type: Small Molecule; Approved; Investigational
Other Brand Names containing Rifaximin: Fatroximin; Normix; Rifacol; Ritacol; Xifaxan;
Absorption: Low absorption in both the fasting state and when administered within 30 minutes of a high-fat breakfast.
Toxicity (Overdose): LD50 > 2 g/kg (orally, in rats)
Protein Binding: Not Available
Biotransformation: 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.
Half Life: Approximately 6 hours.
Dosage Forms of Xifaxan: Tablet Oral
Chemical IUPAC Name: 2S,16Z, 18E,20S,21 S,22R, 23R,24R,25S,26 S,27S,28E)-5,6,21,23, 25-pentahydroxy-27-methoxy-2,4,11,16, 20,22,24,26-octamethyl-2,7- (epoxypentadeca-[1,11,13]trienimino) benzofuro[4,5-e]pyrido[1,2-a] -benzimida-zole-1,15(2H)- dione,25-acetate
Chemical Formula: C43H51N3O11
Rifaximin on Wikipedia: https://en.wikipedia.org/wiki/Rifaximin
Organisms Affected: Enteric bacteria and other eubacteria
