Tigecycline Dosing Basics
Tigecycline, a glycylcycline antibiotic used for complicated infections, has a standard adult dose of 100 mg IV loading, followed by 50 mg IV every 12 hours. Adjustments are needed with certain drugs due to pharmacokinetic interactions.[1]
Rifampin Interaction Mechanism
Rifampin induces CYP3A4 and other enzymes, accelerating tigecycline metabolism and reducing its plasma exposure by about 50-60%. This can lower efficacy against resistant bacteria like MRSA or Acinetobacter.[2][3]
Recommended Dose Adjustment
Increase tigecycline to 100 mg IV every 12 hours (doubling the maintenance dose) when co-administered with rifampin. Retain the 100 mg loading dose. Monitor for breakthrough infections or resistance, and limit combination to cases with no alternatives.[4][5]
Clinical Evidence and Guidelines
Data from population PK studies and case series support this doubling; undosed tigecycline levels drop below MIC for key pathogens. IDSA guidelines note the interaction but defer to PK-adjusted dosing. No pediatric-specific adjustments exist.[3][6]
Potential Risks and Monitoring
Higher doses raise nausea, vomiting, and pancreatitis risk (already tigecycline's main toxicities). Rifampin hepatotoxicity adds concern—check LFTs frequently. Discontinue if ALT/AST >5x ULN.[1][4]
Alternatives if Adjustment Fails
Switch to non-interacting options like vancomycin + beta-lactam for MRSA, or colistin for MDR Gram-negatives. Rifampin-free regimens preferred unless synergy needed for biofilms.[6]
[1]: Tygacil (tigecycline) Prescribing Information
[2]: Drug Interactions with Rifampin - Clin Pharmacokinet (2015)
[3]: Tigecycline PK with Rifampin - Antimicrob Agents Chemother (2009)
[4]: Micromedex Drug Interaction Checker - Tigecycline/Rifampin
[5]: Sanford Guide to Antimicrobial Therapy (2023 edition)
[6]: IDSA Guidelines for Skin/Soft Tissue Infections (2014)