Oseltamivir Amoxicillin

In healthy subjects amoxicillin had no effect on the pharmacokinetics of oral oseltamivir (20). 

In healthy subjects probenecid completely blocked the renal secretion of the active metabolite of oseltamivir after oral administration, increasing its AUC 2.5 times (20). In vitro studies of the metabolite on the human renal organic anionic transporter I (hOATl) were investigated in Chinese hamster ovary cells stably transfected with the transporter. The metabolite was a low-efficiency substrate for hOATl and a very weak inhibitor of hOATl-mediated transport of pora-aminohippuric acid. Probenecid inhibited the transport of the metabolite, pora-aminohippuric acid, and amoxicillin via hOATl. 

Probenecid inhibits the renal secretion of the active metabolite of oseltamivir and marked raises its plasma levels, but this is not clinically relevant because of the wide safety margin of oseltamivir. There was no pharmacokinetic interaction between amoxicillin and oseltamivir, and cimetidine did not alter oseltamivir pharmacokinetics. 

Probenecid appears to completely inhibit the renal tubular secretion of the active metabolite of oseltamivir via the anionic renal transporter process. Oseltamivir does not alter amoxicillin pharmacokinetics, suggesting minimal potential to inhibit the renal anionic transport process. Cimetidine, which inhibits the renal tubular secretion of drugs via the cationic secretion transport process, had no effect on oseltamivir. 

Probenecid markedly increased the AUC of the active metabolite of oseltamivir, but because of the large safety margin of oseltamivir, this increase is not considered to be clinically relevant. " Oseltamivir did not alter amoxicillin pharmacokinetics, and is therefore unlikely to interact with other renally secreted organic acids. Other drugs that are involved in the active anionic tubular secretion mechanism are also unlikely to interact. Cimetidine does not interact with oseltamivir, and other drugs that are inhibitors of the renal cationic secretion transport process are unlikely to interact. ... 

---