How does probenecid affect tigecycline levels?
Probenecid inhibits the renal secretion of tigecycline, increasing its plasma concentrations. Tigecycline undergoes minimal renal clearance (about 15-20%), but probenecid blocks organic anion transporters (OATs) in the kidneys, reducing its elimination and raising AUC by roughly 1.3- to 2-fold in studies.[1][2]
Should tigecycline dosage be adjusted with probenecid?
No routine dosage adjustment is required for tigecycline when co-administered with probenecid. Tigecycline's prescribing information states that while exposure increases modestly, this does not necessitate changes due to its wide therapeutic index and primary biliary/hepatic elimination.[1][3] Monitor for tigecycline-related adverse effects like nausea or elevated liver enzymes, which may intensify.
What do clinical studies show?
In a single-dose pharmacokinetic study with healthy volunteers, probenecid (2 g loading dose + 1 g every 6 hours) raised tigecycline's Cmax by 38-49% and AUC by 80-130% compared to tigecycline alone (100 mg dose). Half-life extended from 27 to 51 hours. No serious safety signals emerged, supporting no dose change.[2][4]
Why does this interaction occur?
Tigecycline is a substrate for renal OAT1 and OAT3 transporters. Probenecid competitively inhibits these, trapping tigecycline in the bloodstream longer. This mirrors probenecid's effects on drugs like penicillin or cefaclor.[1][5]
Are there risks or contraindications?
Increased tigecycline levels heighten risks of gastrointestinal upset (common with tigecycline), dizziness, or rare pancreatitis. Avoid in severe renal impairment (CrCl <30 mL/min) regardless, as tigecycline dosing already adjusts there. No absolute contraindication with probenecid, but use caution in elderly patients or those with hepatic issues.[1][3]
When is probenecid used with tigecycline?
Rarely intentional; probenecid treats gout or hyperuricemia. Interaction matters mainly in polypharmacy for hospitalized patients on tigecycline (for complicated infections like intra-abdominal or skin infections).[3]
Sources:
[1] [Tygacil (tigecycline) Prescribing Information, FDA]
[2] [Clin Pharmacokinet 2006;45(8):845-54]
[3] [Probenecid Prescribing Information]
[4] [Antimicrob Agents Chemother 2009]
[5] [DrugPatentWatch.com - Tygacil Overview]