Validated HPLC-UV detection method for the simultaneous determination of ceftolozane and tazobactam in human plasma.

AIM: A simple, rapid, economical and sensitive HPLC-UV method was developed for the simultaneous quantification of ceftolozane and tazobactam in plasma samples. METHODOLOGY: After deproteinization followed by a liquid-liquid back-extraction, the compounds were separated on a C18 column (150 mm × 4.6 mm, 5 µm) with UV-visible detection at 220 nm. The mobile phase consisted of acetonitrile and potassium dihydrogenphosphate buffer at pH 3.0 (8:92, v/v), delivered isocratically at a flow rate of 1.0 ml/min and at a column oven temperature of 30°C. Cefepime was used as an internal standard. RESULTS: Linearity was achieved in the concentration range of 0.50-100.00 µg/ml for ceftolozane and 0.25-50.00 µg/ml for tazobactam. The intra- and interday precision showed good reproducibility with coefficients of variation of less than 9.26% for ceftolozane and 9.62% for tazobactam. CONCLUSION: The sample preparation procedure avoids expensive or time-consuming steps used by other previously published methods. The methodology was validated according to standard guidelines and was used for quantification of ceftolozane and tazobactam in plasma samples from critically ill patients.

Utility of routine laboratory preoperative tests based on previous results: Time to give up.

INTRODUCTION: The usefulness and cost-effectiveness of routine laboratory preoperative tests (POTs) have been challenged recently. In fact, the American Society of Anesthesiologists (ASA) Task Force has stated that test results obtained from the medical record within 6 months of surgery generally are mostly acceptable. The aim of our study was to evaluate the degree of utility of POTs and their clinical benefit based on this recommendation. MATERIAL AND METHODS: We studied retrospectively every routine POT request from 8 randomly selected weeks in 2016. Every POT contained glucose, creatinine, haemoglobin and coagulation tests (PT-INR). Each pathological result for these tests was registered and classified as "expected" (if previous pathological result within 6 months existed for that test) or "unexpected" (if previous pathological result within 6 months did not exist for that test). Results of ASA physical status classification (a system for assessing the fitness of patients before surgery) and changes in patient management after POTs were retrieved from medical history as well. RESULTS: A total of 4516 tests (from 1129 patients) were analysed and 498 results were found pathological (11%). Of these, 403 were expected (8.9%) and 95 unexpected (2.1%). There was not any change in anaesthetic management for any patient due to these findings. CONCLUSIONS: Routine POTs are an inefficient and low-value service. POTs have to be always ordered selectively after a previous consideration of specific information obtained from several sources (medical records, interviews, examinations, type of surgery) and only if the information obtained will result in changes in the management of the patient.