Rifaximin

Mechanism :

Rifaximin inhibits bacterial RNA synthesis by binding to bacterial DNA-dependent RNA polymerase.

Indication :

Hepatic Encephalopathy
Irritable bowel syndrome with diarrhea
Traveller’s diarrhea in children ≥12 years of age

Contraindications :

Hypersensitivity to rifaximin, other rifamycin antibiotics, or any component of the formulation.

Dosing :

Safety and efficacy has not been established in children <12 years.

Hepatic encephalopathy:

Adults:

400 mg PO every 8 hours for 5 to 10 days.

Traveler’s diarrhea:

>12 years:

200 mg PO 3 times daily for 3 days.

Irritable bowel syndrome with diarrhea:

Adults:

550 mg 3 times daily for 14 days.

Adjunct therapy for C.difficile infection:

>12 years:

200 mg PO 3 times daily for 20 days. Max: 400 mg/dose.

Adverse Effect :

Peripheral edema, dizziness, fatigue, ascites, nausea, depression, pruritus, abdominal pain, pseudomembranous colitis, anemia, muscle spasms, arthralgia, fever.

Interaction :

Cyclosporine: May increase the serum concentration of rifaximin.
P-glycoprotein/ABCB1 Inhibitors: May increase the serum concentration of rifaximin.

Hepatic Dose :

Mild to moderate hepatic impairment: dose adjustment may not be required due to low systemic absorption.
Severe hepatic impairment: Use caution, as systemic absorption may occur and pharmacokinetic of the drug varies highly.