Comparative Pharmacology
Head-to-head clinical analysis: RIFAXIMIN versus SYNERCID.
Peer-Reviewed Evidence
Head-to-head clinical analysis: RIFAXIMIN versus SYNERCID.
RIFAXIMIN vs SYNERCID
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Rifaximin is a non-aminoglycoside, semi-synthetic antibiotic derived from rifamycin that inhibits bacterial RNA synthesis by binding to the beta-subunit of bacterial DNA-dependent RNA polymerase, thereby blocking transcription.
Synercid is a combination of two streptogramin antibiotics, quinupristin and dalfopristin, which bind to the 50S bacterial ribosome and inhibit protein synthesis. Quinupristin binds to the 23S rRNA near the peptidyl transferase center, while dalfopristin binds to a nearby site and enhances quinupristin's binding. The synergistic effect results in irreversible inhibition of bacterial protein synthesis.
550 mg orally three times daily for 14 days for travelers' diarrhea; 200 mg orally three times daily for 3 days for irritable bowel syndrome with diarrhea; 400 mg orally three times daily for 7 days for hepatic encephalopathy.
7.5 mg/kg IV every 8 hours, administered as a 60-minute infusion.
None Documented
None Documented
Clinical Note
moderateRifaximin + Digoxin
"The serum concentration of Digoxin can be increased when it is combined with Rifaximin."
Clinical Note
moderateRifaximin + Levofloxacin
"The serum concentration of Levofloxacin can be increased when it is combined with Rifaximin."
Clinical Note
moderateRifaximin + Estrone sulfate
"The serum concentration of Estrone sulfate can be decreased when it is combined with Rifaximin."
Clinical Note
moderateRifaximin + Tranilast
The terminal elimination half-life is approximately 1.8 to 2.5 hours in patients with normal hepatic function. Due to negligible systemic absorption, the half-life has limited clinical relevance; drug action is largely confined to the gastrointestinal tract.
The terminal elimination half-life is approximately 0.85 hours for dalfopristin and 1.3 hours for quinupristin; however, the active metabolite of quinupristin has a half-life of about 3.5 hours, supporting twice-daily dosing.
Rifaximin is primarily eliminated in feces as unchanged drug (>96% of an oral dose). Renal excretion is negligible (<0.4%). Biliary excretion is minimal due to poor systemic absorption.
Primarily hepatic metabolism with biliary excretion; approximately 15% of the dalfopristin dose and 32% of the quinupristin dose are excreted unchanged in feces; renal excretion is minor (<5% for both components).
Category A/B
Category C
Antibiotic
Antibiotic
"The serum concentration of Tranilast can be decreased when it is combined with Rifaximin."