Development of a SPE-LC-MS Method for the Quantitation of Palbociclib and Abemaciclib in Human Plasma.

Palbociclib and abemaciclib are two cyclin-dependent kinases 4 and 6 used for breast cancer treatment. Levels of these medicines present a significant interindividual variability, so monitoring those concentrations might be necessary in therapy. Most of the methods presented so far in the literature use simple protein precipitation of plasma proteins as sample preparation method followed by direct injection of the supernatant into the LC instrument, preceded or not by a simple filtration step. Within that approach, the probability of injecting proteins in the chromatographic system is increased. With the purpose of obtaining a cleaner extract of the drugs, we developed and validated a simple and accurate LC-MS method for determining palbociclib and abemaciclib in human plasma. Solid phase extraction (SPE) using Oasis PRiME HLB® cartridges was used for plasma sample preparation. The method provided clean extracts with a recovery extraction higher than 85% for both compounds. Separation was achieved by high-performance liquid chromatography (HPLC), using a C18 (4.6 × 50 mm) column, with a gradient elution of ammonium acetate/acetic acid-acetonitrile as the mobile phase. Detection was performed by mass spectrometry (MS) in single ion recording (SIR) mode. Intra-day and inter-day precision data for both analytes were 3.8-7.2% and 3.6-7.4%, respectively. Calibration curves were both linear between 2 and 400 ng/mL with a correlation coefficient higher than 0.998. The LC-MS method can be used to quantify the drugs in human plasma in routine analysis. The method proved to be useful in determining real plasma levels in patients involved in cancer therapy. Drug concentrations were determined in a 10 min run-time, including re-equilibration of the column.

Simultaneous Determination of Two Tyrosine Kinase Inhibitors in Tablets by HPLC-MS analysis.

The class of tyrosine kinase inhibitors (TKIs) is represented by a group of compounds which are currently used in the treatment of different types of cancer. These oral medicines present a narrow therapeutic index and a large inter-and intra-individual variability. Within this work, a simple, accurate and rapid reversed phase ultra-high-performance liquid chromatographic (RP-UHPLC) method with mass spectrometric (MS) detection for simultaneous analysis of two TKIs, ibrutinib and ruxolitinib, using pentoxifylline as internal standard (IS) in tablet dosage forms is presented. The separation was carried out on a Waters (Milford, Massachusetts, USA) Arc System coupled with a Waters QDa mass detector. The column used was a Waters CORTECS C18 (4.6×50mm, 2.7µm); a gradient elution was carried out using a mixture of ammonium formate 10 mM aqueous solution and acetonitrile. The flow rate of the mobile phase was set to 0.5mL/min. The column temperature was equilibrated to 40°C. The injected volume was 5µL. All samples were kept at 20°C during the entire analysis. Mass spectra were recorded in positive ionization mode in the range of m/z 100-400 for ruxolitinib and m/z 100-500 for ibrutinib. Quantification was established in single ion recording (SIR) mode for each compound, using pentoxifylline as internal standard. The method was validated according to International Guidelines in terms of stability, limit of detection, limit of quantitation, linearity, precision and accuracy. The validated method can be successfully applied for simultaneous determination of TKIs in tablet dosage forms.

Chromatographic analysis of local anesthetics in biological samples.

This paper reviews gas and liquid chromatographic methods for screening, identification and quantification of local anesthetics and/or their metabolites in biological samples. Basic information about sample preparation, separation, detection, and quantification of each procedure is summarised. The pros and cons of the various procedures are critically discussed.