Validation and Clinical Application of a New Liquid Chromatography Coupled to Mass Spectrometry (HPLC-MS) Method for Dalbavancin Quantification in Human Plasma

Abstract

Dalbavancin (DBV) is an intravenous long-acting second-generation glycolipopeptide antibiotic with high efficacy and excellent tolerability, approved for use in the treatment of Gram-positive skin and skin structure infections (ABSSSI). Nevertheless, little is known about its pharmacokinetic/pharmacodynamic (PK/PD) properties in real life, which is also due to technical challenges in its quantification in human plasma, preventing an effective application of therapeutic drug monitoring (TDM). In fact, DBV has a high affinity to plasma proteins, possibly resulting in poor recovery after extraction procedure. The aim of this study was to validate a simple, cheap and reliable HPLC-MS method for use in TDM, in accordance with FDA and EMA guidelines. The optimized protein precipitation protocol required 50 μL of plasma, while chromatographic analysis could be performed in 12 min/sample. This method fulfilled the guidelines requirements and then, it was applied for routine DBV TDM in patients receiving off-label high doses (two 1500 + 1500 mg weekly infusions instead of 1000 + 500 mg), with normal renal function or undergoing hemodialysis: continuous hemodiafiltration caused a relevant reduction in DBV exposure, while intermittent dialysis showed comparable DBV concentrations with those of patients with normal renal function. This confirmed the eligibility of the presented method for use in TDM and its usefulness in clinical practice.

Fast and Simple Liquid Chromatography-Isotope Dilution Tandem Mass Spectrometry Method for Therapeutic Drug Monitoring of Dalbavancin in Long-Term Treatment of Subacute and/or Chronic Infections

“…We used for extractive protein-crash down the MeOH:H 2 O (3:1 v / v ) mixture in a stepwise fashion after diluting the microsamples with water (1:17 v / v ), as this procedure may facilitate the handling of very small sample volume like ours. The extraction recovery of our method was high (about 87%) at all of the concentration levels ( Table 4 ), and resulted even higher than those observed previously in other studies in which different extraction solvent combinations were used [ 18 , 19 , 20 ].…”

“…The LLOQ of our method is similar to that of the method of Alebic-Kolbah et al (0.1 mg/L), but the sample volume used by them (50 µL) was much higher than that used by us (3 µL). Thus, the present method is much more sensitive than those published so far [ 17 , 18 , 19 , 24 ].…”

“…It was successfully validated and applied for TDM of DBV concentrations in clinical practice. The high specificity of this method is probably related to the MRM transitions that we selected, which are the same used by Alebic-Kolbah et al but different from those employed by others [ 19 , 20 ]. The fact of adopting a different combination of extraction solvents in our methods could have potentially brought different interfering endogenous or exogenous compounds in the analysis.…”

“…DBV has very high plasma protein binding, so that its extraction from human plasma could be challenging [ 25 ]. Several solvent extraction-precipitation procedures can be adopted for DBV recovery from biological samples, such as ACN:MeOH (50:50) [ 19 ], ACN:H 2 O (20:80) [ 18 ], or pure methanol [ 20 ]. We used for extractive protein-crash down the MeOH:H 2 O (3:1 v / v ) mixture in a stepwise fashion after diluting the microsamples with water (1:17 v / v ), as this procedure may facilitate the handling of very small sample volume like ours.…”

“…One is based on high-performance liquid chromatography coupled with ultraviolet-visible detection (HPLC-UV-VIS) and has acceptable bias and precision but was tested only in three clinical cases for TDM-based dose optimization of DBV [ 17 ]. The other two methods were based on HPLC coupled with tandem mass spectrometry (LC-MS/MS) and used plasma sample aliquots of 50 or more microliters (µL) for the analysis [ 18 , 19 , 20 ].…”