A reduction in
serum aminoglycoside levels can occur if
aminoglycosides and
penicillins are given together to patients with severe
renal impairment. Carbenicillin, piperacillin and ticarcillin have been implicated with both gentamicin and tobramycin. Netilmicin appears not to interact with piperacillin. No interaction of importance appears to occur either with
intravenous aminoglycoside and
penicillins in those with normal
renal function, or between
aminoglycosides and carbapenems.
In patients with
renal impairment it has been recommended that the penicillin dosage should be adjusted according to
renal function, and the
serum levels of both antibacterials closely monitored. However, note that antibacterial inactivation can continue in the assay sample, and rapid assay is probably necessary. There would seem to be no reason for avoiding concurrent use in patients with normal
renal function because no significant
in vivo inactivation appears to occur.