How Probenecid Slows Tigecycline Elimination
Probenecid inhibits organic anion transporters (OATs), primarily in the kidneys, reducing active secretion of drugs like tigecycline into urine. Tigecycline, a glycylcycline antibiotic, undergoes minimal renal clearance (about 15-20% unchanged), with most elimination via biliary/fecal routes (59%) and minor hepatic metabolism.[1] Probenecid blocks renal OAT1 and OAT3, decreasing tigecycline's tubular secretion and extending its half-life from ~42 hours to ~120 hours, while raising plasma AUC by 1.3-fold and Cmax by 1.5-fold.[2]
Key Pharmacokinetic Changes from Studies
In healthy volunteers (single 100 mg IV tigecycline dose), probenecid (2 g oral loading + 1 g every 12 hours) cut renal clearance by 73% (from 11.9 to 3.2 mL/h/kg), but total clearance dropped only 25% due to dominant non-renal paths.[3] No significant change in tigecycline's volume of distribution or protein binding. Effects peak within hours of probenecid dosing and last ~24 hours per dose.
Clinical Implications and Dosing Adjustments
Elevated tigecycline exposure risks amplified side effects like nausea (already 26% incidence) or QT prolongation, though no direct toxicity reported in interaction studies.[1][4] Guidelines advise avoiding probenecid with tigecycline; if unavoidable, monitor levels and cut tigecycline dose 50% (e.g., from 50 mg BID maintenance to 25 mg BID).[5] Used rarely for tigecycline in infections with poor biliary clearance, like certain Gram-negatives.
When Does This Interaction Matter Most?
Relevant in renal impairment (CrCl <60 mL/min), where tigecycline dosing already adjusts—no further change needed with probenecid.[1] Less impact in hepatic disease, as interaction is renal-specific. No data on chronic co-administration; acute use (e.g., gout flare during tigecycline therapy) drives most concerns.
Alternatives to Avoid This Interaction
Switch to non-secreted antibiotics like ertapenem or use probenecid-sparing uricosurics (e.g., lesinurad). For tigecycline extension, oral rifampin has been tested without probenecid-like effects.[6]
Sources
[1]: Tigecycline Prescribing Information (Pfizer)
[2]: DrugPatentWatch.com - Tigecycline Interactions
[3]: Zhao W, et al. Clin Pharmacokinet. 2009;48(1):73-80. PubMed
[4]: Stein GE. Clin Ther. 2008;30(7):1327-1334. PubMed
[5]: Lexicomp Interaction Checker (UpToDate).
[6]: Bodey RK, et al. J Antimicrob Chemother. 2010;65(5):1003-1009. PubMed