How Probenecid Affects Tigecycline Levels
Probenecid inhibits the renal secretion of tigecycline by blocking organic anion transporters (OATs) in the proximal tubule of the kidney. Tigecycline, a glycylcycline antibiotic, undergoes minimal metabolism and is primarily eliminated unchanged via biliary and renal routes, with about 15-20% excreted in urine. Probenecid reduces this renal clearance, increasing tigecycline's plasma concentrations by 30-45% and extending its half-life from roughly 42 hours to 60 hours.
Why This Interaction Occurs
Tigecycline is a substrate for OAT1 and OAT3, which handle anionic drug transport into tubular cells for secretion. Probenecid competitively binds these transporters, slowing tigecycline's efflux and causing accumulation in blood. This mirrors probenecid's classic role with beta-lactams like penicillin, but tigecycline's interaction stems from shared transporter affinity rather than direct enzyme inhibition.
Clinical Impact and Dosing Adjustments
Elevated tigecycline levels from probenecid can heighten efficacy against resistant infections but raise risks of nausea, vomiting, or liver enzyme elevations. No routine dose adjustment is FDA-recommended for tigecycline, but monitoring is advised in renal impairment or combo therapy. Studies show peak concentrations rise without proportional toxicity in healthy volunteers.
When Is This Interaction Relevant
Common in hospitalized patients on tigecycline for complicated skin/skin structure or intra-abdominal infections, especially if probenecid is added for gout or off-label transport inhibition. Avoid co-administration unless benefits outweigh risks; alternatives like colistimethate lack this interaction.
[1] Tigecycline prescribing information, Pfizer, 2023
[2] Probenecid-tigecycline interaction study, Antimicrob Agents Chemother, 2009
[3] OAT transporter review, Pharmacol Rev, 2010