piperacillin/tazobactam

( 7.1 ) • Probenecid prolongs the half-lives of piperacillin and tazobactam and should not be co-administered with ZOSYN unless the benefit outweighs the risk. 7.2 Probenecid Probenecid administered concomitantly with ZOSYN prolongs the half-life of piperacillin by 21% and that of tazobactam by 71% because probenecid inhibits tubular renal secretion of both piperacillin and tazobactam. Probenecid should not be co-administered with ZOSYN unless the benefit outweighs the risk.

Mechanism: Probenecid prevents your kidneys from clearing the antibiotic out of your system, which makes the drug stay in your body for a longer time.

What to do: You should not take these together unless your doctor determines the benefits are greater than the risks.

7.6 Methotrexate Limited data suggests that co-administration of methotrexate and piperacillin may reduce the clearance of methotrexate due to competition for renal secretion. The impact of tazobactam on the elimination of methotrexate has not been evaluated. If concurrent therapy is necessary, serum concentrations of methotrexate as well as the signs and symptoms of methotrexate toxicity should be frequently monitored.

Mechanism: Both drugs try to leave the body through the kidneys at the same time, which can slow down how fast methotrexate is removed from your system.

What to do: Your doctor should check your blood levels of methotrexate and watch for signs of side effects more often.

( 7.2 ) • Co-administration of ZOSYN with vancomycin may increase the incidence of acute kidney injury. Monitor kidney function in patients receiving ZOSYN and vancomycin. 7.3 Vancomycin Studies have detected an increased incidence of acute kidney injury in patients concomitantly administered piperacillin and tazobactam and vancomycin as compared to vancomycin alone [see Warnings and Precautions (5.6) ] .

Mechanism: Taking these two antibiotics together can increase the risk of sudden damage to your kidneys.

What to do: Your healthcare provider should monitor your kidney function closely while you are receiving both of these medications.

ZOSYN, which contains EDTA, is compatible with amikacin and gentamicin for simultaneous Y-site infusion in certain diluents and at specific concentrations.

Mechanism: These drugs can be safely given through the same IV line at the same time as long as specific liquids and amounts are used.

What to do: Your nurse or pharmacist will ensure the drugs are mixed in the correct way to be given together safely.

7 DRUG INTERACTIONS • ZOSYN administration can significantly reduce tobramycin concentrations in hemodialysis patients. Monitor tobramycin concentrations in these patients. In vivo inactivation : When aminoglycosides are administered in conjunction with piperacillin to patients with end-stage renal disease requiring hemodialysis, the concentrations of the aminoglycosides (especially tobramycin) may be significantly reduced and should be monitored.

Mechanism: In patients on dialysis, piperacillin can chemically deactivate tobramycin in the blood, making the antibiotic less effective.

What to do: If you are on dialysis, your doctor should monitor your tobramycin blood levels to make sure the dose is still working.