Composition
Each coated tablet contains rifaximin- 200mg
Indications
Treatment of gastrointestinal infections caused by enteropathogenic agents
sensitive to rifaximin. Pre and postoperative prophylaxis of infections in colon surgery.
Reduction of intestinal bacterial flora in patients with liver failure
(hyperammonemia).
Posology
From 600 to 800 mg/day distributed in two or three doses for 5 to 7 days.
Presentation
Box with 12 coated tablets of 200 mg per blister
Contraindications
Hypersensitivity to the active substance, active derivatives of Rifaximin Alfa or to any of the excipients. Hypersensitivity reactions include exfoliative dermatitis, angioneurotic edema, and anaphylaxis.
There may be some cases of intestinal obstruction.
Warnings
Patients should be informed that although drug absorption is negligible (less than 1%), like all Rifampicin derivatives, this drug can cause a reddish coloration of the urine.
Precautions
- Clinical data has shown that Rifaximin Alfa is not effective in the treatment of intestinal infections due to invasive enteric pathogens such as Campylobacter jejuni, Salmonella spp. Shighela spp, which usually cause diarrhea, fever, blood in the stools and increased frequency of them. Rifaximin Alfa should be discontinued if diarrhea symptoms worsen or persist for more than 48 hours and alternative antibiotic treatment should be considered.
- Development of Clostridium difficile-associated diarrhea (CDAD) has been reported with almost all microbial agents, including Rifaximin Alfa. The total association of Rifaximin Alfa for the treatment of CDAD and pseudomembranous colitis (PMC) cannot be ruled out.
- Concomitant co-administration of P-glycoprotein inhibitors with Rifaximin Alfa may substantially increase the systemic exposure of this drug. If it is necessary to use a P-glycoprotein inhibitor, such as Ciclosporin, together with Rifaximin Alfa, all necessary precautions must be taken. In patients with hepatic insufficiency there may be a potential additive effect due to reduced metabolism and concomitant use with P-glycoprotein inhibitors, which could subsequently increase the systemic exposure of Rifaximin Alfa.
- Due to effects on the intestinal flora, the efficacy of extrogenous oral contraceptives may decrease after administration of Rifaximin Alfa. However, these interactions have not been frequently reported. Additional contraceptive precautions are recommended, particularly if the estrogen content of oral contraceptives is less than 50 μg.
Interaction with other medications
- There is no experience regarding the administration of Rifaximin Alfa to subjects who are taking another antibacterial agent derived from Rifampicin to treat a systemic bacterial infection. In vitro data show that Rifaximin Alfa did not inhibit the major drug-metabolizing cytochrome P-450 (CYP) enzymes (CYPs 1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3a4). In in vitro studies without induction, Rifaximin Alfa did not induce CPY 1A2 and CPY2B6, but was a weak inducer of CPY3A4.
- In healthy subjects, clinical drug interaction studies demonstrated that Rifaximin Alfa did not significantly affect the pharmacokinetics of concomitantly administered CPY3A4 substrates (eg, warfarin, antiepileptics, antiarrhythmics), due to higher systemic exposure relative to healthy subjects.
- An in vitro study suggests that Rifaximin Alpha is a moderate substrate for P-glycoprotein-(P-gp) and is metabolized by CPYA4. It is unknown whether concomitant medications that inhibit CPY3A4 can increase the systemic exposure of Rifaximin.
Concomitant P-glycoprotein inhibitors
- In healthy subjects, coadministration of a single dose of cyclosporine (600 mg), a potent P-glycoprotein inhibitor, with a single dose of Rifaximin Alfa (500 mg) resulted in an 83- to 124-fold increase in of Rifaximin Alpha for mean Cmax at AUC ∞. The clinical significance of this increase in systemic exposure is unknown.
- The potential for drug interactions occurring at the level of transporter systems has been raised in vitro and studies suggest that a clinical interaction between Rifaximin Alpha and other compounds that undergo efflux through P-gp and other transport proteins unlikely (MDR1, MRP2, MRP4, BCRP, and BSEP).
- In the case of charcoal administration, Rifaximin Alfa should be taken at least 2 hours after intake.
