Synthesis of [13 C6 ]-ibrutinib

Carbon-13 labeling of ibrutinib for human microdosing

Ibrutinib is an oral medication for the treatment of B cell malignancies. During its clinical development, a stable isotopologue of ibrutinib was required for the assessment of the drug's absolute oral bioavailability via intravenous microdosing. The following work describes a 10-step, gram-scale production of carbon-13 labeled ibrutinib from [¹³ C₆ ]phenol (¹³ C₆ , 99%) in 31% overall yield with >99% chemical purity and >99% enantiomeric excess (ee), suitable for intravenous microdosing in humans.

Differential adsorption of an analyte and its D4, D5 and 13C6 labeled analogues combined with instrument-specific carry-over issues: The Achilles' heel of ibrutinib TDM

At present, therapeutic drug monitoring is the standard in pharmacotherapy using medications with a narrow therapeutic index or showing serious adverse effects, such as in the case of ibrutinib. A technique commonly used for this purpose is liquid chromatography-tandem mass spectrometry combined with isotope dilution in sample processing. Although this method provides a high degree of reliability, its use can be complicated with some specific factors and does not guarantee trouble-free analysis. This paper is focused on investigating issues related to the differential adsorption of ibrutinib and its D₄, D₅ and ¹³C₆ isotopically labeled analogues combined with instrument-specific carry-over. The results of the research point out the significantly different adsorption behavior of ibrutinib in fluidics of LC-MS compared with that of its D₄, D₅ and ¹³C₆ stable isotope labeled analogues, showing preferential adsorption of non-labeled compound. The investigation also pointed to a strong affinity of ibrutinib to polymeric surfaces under specific conditions, which has to be taken into consideration during sample preparation and analysis. Our work opens a new field for the discussion of scarcely reported problem related to the use of stable isotope labeled internal standards in LC-MS/MS analysis.