Simultaneous Quantification and Pharmacokinetic Study of Five Homologs of Dalbavancin in Rat Plasma Using UHPLC-MS/MS

A Systematic Degradation Kinetics Study of Dalbavancin Hydrochloride Injection Solutions

The degradation kinetics of the glycopeptide antibiotic dalbavancin in solution are systematically evaluated over the pH range 1-12 at 70°C. The decomposition rate of dalbavancin was measured as a function of pH, buffer composition, temperature, ionic strength, and drug concentration. A pH-rate profile was constructed using pseudo first-order kinetics at 70°C after correcting for buffer effects; the observed pH-rate profile could be fitted with standard pseudo first order rate laws. The degradation reactions of dalbavancin were found to be strongly dependent on pH and were catalyzed by protons or hydroxyl groups at extreme pH values. Dalbavancin shows maximum stability in the pH region 4-5. Based on the Arrhenius equation, dalbavancin solution at pH 4.5 is predicted to have a maximum stability of thirteen years under refrigerated conditions, eight months at room temperature and one month at 40°C. Mannosyl Aglycone (MAG), the major thermal and acid degradation product, and DB-R6, an additional acid degradation product, were formed in dalbavancin solutions at 70°C due to hydrolytic cleavage at the anomeric carbons of the sugars. Through deamination and hydrolytic cleavage of dalbavancin, a small amount of DB-Iso-DP2 (RRT-1.22) degradation product was also formed under thermal stress at 70°C. A greater amount of the base degradation product DB-R2 forms under basic conditions at 70°C due to epimerization of the alpha carbon of phenylglycine residue 3.

Strategies to stabilize dalbavancin in aqueous solutions: Section 4—identification of heat degradation products in 2-hydroxypropyl-β-cyclodextrin and divalent metal ion solutions at pH 4.5 and 7.0

Heat stress studies have been conducted in support of developing a heat-stable liquid solution of dalbavancin. The degradation products that form in heat-stressed buffered dalbavancin solutions have been identified, including the known major degradation product, mannosyl aglycone (MAG), and four previously uncharacterized compounds. Liquid chromatography-mass spectrometry/mass spectrometry (LC–MS/MS) was used to identify the degradation products of dalbavancin in acetate- and phosphate-buffered solutions under thermal stress at 70 °C and the changes in the degradation pattern in the presence of 2HPβCD and divalent metal ions. Although Ca2+, Mg2+, and Zn2+ did not reduce dalbavancin degradation under thermal stress in acetate buffer, 2HPβCD significantly reduced its overall degradation, in particular, the formation of MAG. This protective effect was enhanced by the addition of Ca2+ to the formulation. In phosphate buffer, MAG formation was also reduced by the addition of 2HPβCD, although significant increases in other degradation products were observed in this case. The addition of Mg2+ to 2HPβCD significantly reduced the overall degradation while increasing MAG formation somewhat. The results strongly suggest that 2HPβCD forms a complex with the hydrophobic glycone tail of dalbavancin, suppressing hydrolysis of the glycosidic bond.

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

Dalbavancin (DBV) is a long-acting antistaphylococcal lypoglycopeptide that is being increasingly used for long-term treatment of a wide range of subacute and/or chronic infections, mainly osteo-articular infections (OAI). Population pharmacokinetic studies showed that two 1500 mg doses 1 week apart can ensure effective treatment for several weeks. In this scenario, therapeutic drug monitoring (TDM) can be a helpful tool for providing clinicians with real-time feedback on the duration of optimal treatment by measuring drug concentrations over time in each single patient. The aim of this study was to develop and validate a fast and simple analytical method based on the Liquid Chromatography-Isotope Dilution Tandem Mass Spectrometry (ITD LC-MS/MS) technique for measuring DBV concentrations in human plasma microsamples. It will allow an innovative, very convenient and minimally invasive way of sampling. Analysis was performed by simple single-step sample preparation and very short instrumental run time (4 min). Analytical performance met all criteria in terms of specificity, sensitivity, linearity, precision, accuracy, matrix effect, extraction recovery, limit of quantification, dilution integrity and stability under different conditions set by the European Medicines Agency (EMA) for drug quantification by means of bioanalytical methods. The method was successfully applied for measuring DBV concentrations (range = 2.0-77.0 mg/L) in a cohort of patients receiving long-term DBV treatment of subacute and/or chronic infections.

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

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.