title: Quantitation and stability of piperacillin and tazobactam in plasma and ultrafiltrate from patients undergoing continuous venovenous hemofiltration by HPLC.
abstract: Simple and reproducible HPLC methods for the determination of piperacillin and tazobactam have been developed and a complete stability study carried out. The method for piperacillin plasma samples consisted of protein precipitation with methanol using penicillin G as internal standard. No sample preparation was needed for ultrafiltrate samples. Tazobactam sample preparation involved protein precipitation with acetonitrile and the removal of lipids with dichloromethane. Piperacillin separation was performed on a microBondapack C(18) column (300 x 3.9, 10 microm) and tazobactam on a Novapack C(18) column (150 x 3.9, 4 microm) with UV detection set at 229 and 225 nm, respectively. The mobile phase consisted of phosphate buffer-acetonitrile, delivered at 1.5 mL[sol ]min. Calibration curves determination coefficients were >or=0.999 and response factors CV% < 5%. Intra- and inter-assay precision and accuracy of the quality control and limit of quantification were satisfactory. Plasma and ultrafiltrate samples were stable at -20 and -80 degrees C for 2 months and after three freeze-thaw cycles. In the chromatographic rack, tazobactam ultrafiltrate samples were stable for 24 h and plasma samples for 12 h, piperacillin ultrafiltrate samples for 8 h, but plasma samples for only 4 h. Storage of piperacillin samples at 4 degrees C until analysis is recommended. Piperacillin was stable in the presence of tazobactam.
authors.affiliation: Laboratory of Pharmacy and Pharmaceutical Technology, Faculty of Pharmacy, University of the Basque Country, Vitoria-Gasteiz, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Arzuaga
authors.forename: A
authors.initials: A
authors.lastname: Isla
authors.forename: A R
authors.initials: AR
authors.lastname: Gascón
authors.forename: J
authors.initials: J
authors.lastname: Maynar
authors.forename: A
authors.initials: A
authors.lastname: Martín
authors.forename: M A
authors.initials: MA
authors.lastname: Solinís
authors.forename: D
authors.initials: D
authors.lastname: Toral
authors.forename: J L
authors.initials: JL
authors.lastname: Pedraz
mesh_terms: D000900:Anti-Bacterial Agents / Q000032:analysis* / Q000097:blood; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006440:Hemofiltration / Q000379:methods*; D006801:Humans; D010397:Penicillanic Acid / Q000031:analogs & derivatives* / Q000032:analysis / Q000097:blood; D010878:Piperacillin / Q000032:analysis* / Q000097:blood; D012680:Sensitivity and Specificity; D000078142:Tazobactam; D014462:Ultrafiltration
chemical_list: D000900:Anti-Bacterial Agents; D010397:Penicillanic Acid; D000078142:Tazobactam; D010878:Piperacillin