Development, validation, and application of an LC-MS/MS method for the quantification of the novel antibiotic drug lefamulin (Xenleta®) and its main metabolite 2R-hydroxy lefamulin in human plasma.

Lefamulin (Xenleta®) is a first in-class systemic pleuromutilin antibiotic that inhibits bacterial protein synthesis and selectively binds to a highly conserved region of the peptidyl transferase center of the bacterial 50S ribosomal subunit. A total of twenty-five Phase 1 clinical studies, one Phase 2 study in acute bacterial skin and skin structure infections (ABSSSI), and two pivotal Phase 3 studies in adults with community acquired bacterial pneumonia (CABP) have been completed. Xenleta® (lefamulin) has been approved by the FDA on August 19, 2019, by Health Canada on July 10, 2020, and by the EMA on July 28, 2020 for the oral and IV treatment of CABP in adults.

Pharmacokinetics/pharmacodynamics of lefamulin in a neutropenic murine pneumonia model with Staphylococcus aureus and Streptococcus pneumoniae.

Objectives: To present results of preclinical studies that supported further development of lefamulin for treating patients with community-acquired bacterial pneumonia (CABP).

Methods: The effect of bovine lung surfactant on the antibacterial activity of lefamulin against Streptococcus pneumoniae and Staphylococcus aureus was determined by broth microdilution assay. In vitro accumulation of lefamulin was evaluated in J774 mouse macrophages.

Simultaneous assessment of the pharmacokinetics of a pleuromutilin, lefamulin, in plasma, soft tissues and pulmonary epithelial lining fluid.

Background: Lefamulin is a pleuromutilin antibiotic under evaluation for the treatment of bacterial infections, including respiratory tract infections. Currently, there are no high-quality pharmacokinetic data on drug tissue concentrations of lefamulin available.

Methods: A single dose of intravenous lefamulin (150 mg) was given to 12 healthy men.

Application of capillary electrophoresis-mass spectrometry for the investigation of the binding behavior of oxaliplatin to 5'-GMP in the presence of the sulfur-containing amino acid L-methionine.

Capillary electrophoresis-electrospray ionization-mass spectrometry (CE-ESI-MS) has been used for investigating the influence of the sulfur containing amino acid L-methionine (L-Met) on the binding behavior of oxaliplatin (trans-R,R-diaminocyclohexane-(oxalato)platinum(II)) to 5'-GMP. L-Methionine competes with 5'-GMP for the platinum binding site and forms as well as 5'-GMP adducts with oxaliplatin. The formation of the prognosed complexes [Pt(DACH)(L-Met-S,N)]+ and [Pt(DACH)(5'-GMP)2]2- (DACH = 1,2-diaminocyclohexane) could be proved directly by using CE-ESI-MS.

Comparison of the binding behavior of oxaliplatin, cisplatin and analogues to 5'-GMP in the presence of sulfur-containing molecules by means of capillary electrophoresis and electrospray mass spectrometry.

Capillary electrophoresis as well as ESI-MS has been applied for investigating the influence of the sulfur-containing amino acids L-cysteine and L-methionine on the binding behavior of oxaliplatin (trans-R,R-diaminocyclohexane(oxalato)platinum(II)), cisplatin (cis-diamminedichloroplatinum(II)), carboplatin (cis-diammine-1,1-cyclobutanedicarboxylatoplatinum(II)), cis-diammine(malonato)platinum(II) and cis-diammine(2-hydroxymalonato)platinum(II) to 5'-GMP. The presence of L-methionine resulted in a different kind of adduct formation which involves ammine release due to the trans-effect of sulfur. In addition, the time-dependent behavior of the reaction with 5'-GMP changed significantly.