Piperacillin is not absorbed orally, and must therefore be given by intravenous or intramuscular injection. It has been shown that the bacteriocidal actions of the drug do not increase with concentrations of piperacillin higher than 4-6xMIC, which means that the drug is concentration-independent in terms of its actions. Piperacillin has instead shown to offer higher bacteriocidal activity when its concentration remains above the MIC for longer periods of time (50% time>MIC showing the highest activity). This higher activity (present in continuous dosing) has not been directly linked to clinical outcomes, but however does show promise of lowering possibility of resistance and decreasing mortality.
^Lau W, Mercer D, Itani K, et al. (2006). "Randomized, open-label, comparative study of piperacillin-tazobactam administered by continuous infusion versus intermittent infusion for treatment of hospitalized patients with complicated intra-abdominal infection". Antimicrob Agents Chemother50 (11): 3556–61. doi:10.1128/AAC.00329-06. PMC1635208. PMID16940077.