In vitro stability study of 10 beta-lactam antibiotics in human plasma samples

Background and Objectives

Beta-lactam antibiotics are reported for some of them to be subject to a rapid degradation in infusion solutions and in human blood samples. However, the current data of stability available in blood samples are limited to a few number of beta-lactam antibiotics, and the methodology of the corresponding studies may be discussed. The objective of the present study is to evaluate the stability of 10 beta-lactam antibiotics in human plasma samples.

Methods

Stability of amoxicillin, cefazolin, cefepime, cefotaxime, cefoxitin, ceftazidime, ceftriaxone, imipenem, meropenem, and piperacillin was evaluated at low and high concentrations at 20°C, 4°C, −20°C, and −80°C for 1, 7, 60, and 90 days, respectively.

Results

Amoxicillin, cefepime, meropenem, and piperacillin were the least stable antibiotics. The maximum durations allowing the stability for all the evaluated beta-lactams at both tested concentrations were estimated at 3 h, 23 h, 10 days, and 35 days at 20°C, 4°C, −20°C, and −80°C, respectively.

Conclusion

We recommend to transport antibiotic plasma samples in ice at 4°C and even at −20°C if these samples come from external hospitals. Ideally, plasma samples should be stored at −80°C if possible; if not, the analysis of the samples should be performed as soon as possible in the limit of 10 days after a storage at −20°C.