A method for determining the free (unbound) concentration of ten beta-lactam antibiotics in human plasma using high performance liquid chromatography with ultraviolet detection.

With the clinical imperative to further research in the area of optimising antibiotic dosing in the intensive care setting, a simple high performance liquid chromatography method was developed and validated for routinely determining the free (unbound) concentration of ten beta-lactam antibiotics in 200 μL of human plasma. Antibiotics determined include three cephalosporins (ceftriaxone, cephazolin and cephalotin); two carbapenems (meropenem and ertapenem); and five penicillins (ampicillin, piperacillin, benzylpenicillin, flucloxacillin and dicloxacillin). There was a single common sample preparation method involving ultracentrifugation and stabilisation.

Therapeutic drug monitoring of beta-lactam antibiotics in burns patients--a one-year prospective study.

Background: Beta-lactams are first-line antibiotics for the management of superficial infections due to burn injury. There is sparse data available on therapeutic drug monitoring (TDM) in patients with burns in a ward setting. This study was conducted to evaluate the utility of a beta-lactam TDM program in a cohort of burn injury patients in a ward environment.

Free cortisol method comparison: ultrafiltation, equilibrium dialysis, tracer dilution, tandem mass spectrometry and calculated free cortisol.

Background: Free cortisol (FC) can be calculated from measurements of total cortisol and binding proteins or measured after mechanical separation of unbound and bound fractions by equilibrium dialysis or ultrafiltration. FC can then be measured indirectly by 3H-cortisol dilution or directly by immunologic or tandem mass spectrometry assays.

Methods: We compared FC measured with ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC MS/MS) with 3H-cortisol dilution in ultrafiltrates and dialysates and also with calculated FC (Coolens equation).

Measurement of cortisol, cortisone, prednisolone, dexamethasone and 11-deoxycortisol with ultra high performance liquid chromatography-tandem mass spectrometry: Application for plasma, plasma ultrafiltrate, urine and saliva in a routine laboratory.

We describe an ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC MS/MS) method suitable for a routine laboratory to determine endogenous and exogenous glucocorticoids in plasma, plasma ultrafiltrate, urine and saliva in a single analytical run. After addition of a multi-analyte internal standard, a standardised sample preparation procedure with solid phase extraction followed, before injecting into a tandem mass spectrometer with positive mode electron spray ionisation and multiple reactant monitoring acquisition. The chromatography time was 3min.