Rifaximin

Category: pharmacological

Aliases: Xifaxan

Pharmacological Mechanism

Non-absorbed rifamycin — minimal systemic exposure (<1% bioavailability) means minimal CYP induction despite same PXR mechanism. Used for travelers diarrhea, hepatic encephalopathy (gut ammonia), and IBS-D (gut microbiome modulation).

Half-Life (t½)

PO: 6h

Dosing Guidelines

• PO: Typical 400 mg (Range: 200–550 mg)

Target Organ Systems

• digestive

Pathways It Modulates

• Bile acid (inhibitor) — gut microbiota composition; paradoxically often ↑beneficial taxa
• Microbiome short-chain fatty acid signaling (inhibitor) — gut bacteria broadly — alters SCFA producer composition
• Mycobacterial cell envelope + RNA polymerase (inhibitor) — mycobacterial/enterobacteriaceal RNA polymerase β-subunit

Chemical Identifiers

• PubChem CID: 6436173
• Formula: C43H51N3O11
• Molecular weight: 785.88 g/mol
• InChIKey: NZCRJKRKKOLAOJ-XRCRFVBUSA-N
• SMILES: C[C@H]1/C=C/C=C(\C(=O)NC2=C(C3=C(C4=C(C(=C3O)C)O[C@@](C4=O)(O/C=C/[C@@H]([C@H]([C@H]([C@@H]([C@@H]([C@@H]([C@H]1O)C)O)C)OC(=O)C)C)OC)C)C5=C2N6C=CC(=CC6=N5)C)O)/C