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Pharmacology: Pharmacokinetics: Piperacillin and Tazobactam is not absorbed from the gastrointestinal tract. It is well absorbed after intramuscular administration, peak plasma concentrations of 30 to 50 μg per mL being observed 30 to 50 minutes after a dose of 2 g. The pharmacokinetics of Piperacillin and Tazobactam Sodium are reported to be nonlinear and dose-dependent. The plasma half-life is about one hour, but is prolonged in neonates. In patients with severe renal insufficiency there may be a threefold increase in half-life; in those with end stage renal failure half-lives of 4 to 6 hours have been reported, and in those with both renal and hepatic impairment much longer half-lives may result. About 20% of Piperacillin and Tazobactam Sodium in the circulation is bound to plasma proteins.
Piperacillin is widely distributed in body tissues and fluids. It crosses the placenta into fetal circulation and small amounts are distributed into breast milk. There is little diffusion into the CSF except when the meninges are inflamed.
About 60 to 80% of a dose is excreted unchanged in the urine by glomerular filtration and tubular secretion within 24 hours, achieving high concentrations. High concentrations are also found in the bile and about 20% of a dose may be excreted by this route.
Plasma concentration are enhanced if probenecid is administered concomitantly.
Piperacillin with tazobactam: The pharmacokinetics of piperacillin do not appear to be altered by the co-administration of tazobactam, but piperacillin reduces the renal clearance of tazobactam.
