Suitability of Becton Dickinson Vacutainer rapid serum tube for collecting and storing blood samples for antibiotic and anticonvulsant drug monitoring.

Aims: To investigate the suitability of newly developed Becton Dickinson Vacutainer rapid serum tube (RST) for therapeutic drug monitoring of antibiotics and anticonvulsants.

Methods: Two pools of citrated whole blood were created by spiking high and low concentrations of gentamicin, vancomycin, phenytoin, lamotrigine and carbamazepine. After recalcification with 15 mmol/L calcium chloride, spiked whole blood was added into four different Becton Dickinson blood collection tubes: RST, serum separator tube, red top tube and polyethylene plain tube. Serum aliquots were collected at baseline (0 h), 2 h, 24 h, day 3 and day 7. Drug concentrations were measured in batch by HPLC and the Architect c8000.

Results: Gentamicin and vancomycin concentrations were stable up to 7 days in all 4 blood collection tubes. Anticonvulsants results for the RST were stable and did not deviate substantially from those of the red top and plain tubes, and demonstrated better performance than the serum separator tubes that showed significant (≥10% bias, p<0.05) decrease in phenytoin and carbamazepine levels after 3 days of storage.

Conclusions: The RST provides acceptable drug stability over the course of 7 days for gentamicin, vancomycin, phenytoin and lamotrigine and over 3 days for carbamazepine.