Simultaneous LC-ESI-MS/MS Quantification of Levosimendan and Its Metabolites for Therapeutic Drug Monitoring of Cardiac Surgery Patients

Figures

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  Figure 1. Chemical structures of levosimendan (Mr 280.28; m/z 279→227), OR-1855 (Mr 203.24; m/z 204→120), OR-1896 (Mr 245.28; m/z 246→204), metamizole sodium (Mr 333.34), 4-AAP (Mr 203.24; m/z 204→57), and 4-AAAP (Mr 245.28; m/z 246→204).

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  Figure 2. LC-ESI-MS/MS and LLE for levosimendan, OR-1855, and OR-1896. (A) MRM chromatogram for levosimendan (5 nM), OR-1855 (10 nM), and OR-1896 (10 nM) in solvent. (B) Extraction efficiency from serum samples by LLE for levosimendan, OR-1855, and OR-1896 (n = 23). (C) MRM chromatogram of a serum blank. (D) MRM chromatogram of levosimendan, OR-1855, and OR-1896 at their LLOQs of 150 pM (levosimendan) and 500 pM (OR-1855 and OR-1896) in serum. (E) MRM chromatogram for levosimendan, OR-1855, and OR-1896 at 50 nM (middle QC level) and 13C6-labelled internal standards (5 nM) in serum. LC-MS for (A,C–E): Luna C8 (30 mm × 2 mm); 5 mM NH4HCO3 (pH 8.5)/CH3CN (76.6:23.4, v/v); 350 µL/min; MRM: levosimendan (m/z 279→227), OR-1855 (m/z, 204→120), and OR-1896 (m/z 246→204).

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  Figure 3. LC-ESI-MS/MS for levosimendan and metabolites in patient samples. (A) MRM chromatogram for levosimendan, OR-1855, and OR-1896 of a serum sample taken before surgery from a cardiac patient treated with levosimendan. (B) MRM chromatogram of OR-1855 and OR-1896 of a serum sample from a cardiac patient treated with levosimendan with additional metamizole administration taken directly after surgery. (C) MRM chromatogram of 4-AAP and 4-AAAP (both 100 nM) in solvent obtained for the mass transitions of OR-1855 and OR-1896, respectively. LC-MS: Luna C8 (30 mm × 2 mm); 5 mM NH4HCO3 (pH 8.5)/CH3CN (76.6:23.4, v/v); 350 µL/min. MRM: levosimendan (m/z, 279→227), OR-1855 (m/z, 204→120), OR-1896 (m/z, 246→204), 4-AAP (m/z, 204→120), and 4-AAAP (m/z, 246→204).

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  Figure 4. LC-ESI-MS/MS for levosimendan, OR-1855, OR-1896, 4-AAP, and 4-AAAP. (A) MRM chromatogram for levosimendan, OR-1855, OR-1896, 4-AAAP (each 75 nM), and 4-AAP (350 nM). (B) MRM chromatogram of a serum blank. (C) MRM chromatogram for levosimendan, OR-1855, OR-1896, 4-AAP, and 4-AAAP in serum at their respective LLOQs of 450 pM, 1.5 nM, 1.5 nM, 50.0 nM, and 1.35 nM, respectively. (D) MRM chromatogram of levosimendan, OR-1896, OR-1855, and 4-AAAP of a serum sample from a cardiac patient (same patient as in 3B) treated with levosimendan and metamizole taken directly after surgery. LC-MS: Zorbax SB-C8 column (150 mm × 4.6 mm); 5 mM NH4HCO3 (pH 8.5)/CH3CN/CH3OH (67:23:10, v/v); 750 µL/min. MRM: levosimendan (m/z, 279→227), OR-1855 (m/z, 204→120), OR-1896 (m/z, 246→204), 4-AAP (m/z, 204→57), and 4-AAAP (m/z, 246→204).