DEVELOPMENT AND VALIDATION OF HPLC-MS/MS METHOD OF DETERMINATION OF A NEW DERIVATIVE OF VALPROLEIC ACID AND 1,3,4-THIADIAZOLE IN RABBIT BLOOD PLASMAFOR PHARMACOKINETIC STUDY

Objective. To develop and validate the HPLC-mass spectrometric method for determining a new derivative of valproic acid and 1,3,4-thiadiazole in rabbit plasma. Material and methods. The object of the study was N-(5-ethyl-1,3,4-thiadiazol-2-yl) -2-propylpentanamide (valprazolamide) – a new antiepileptic drug from the group of thiadiazole derivatives of valproic acid. Valprazolamide was determined in rabbit plasma using an Agilent 1260 Infinity II high perfor-mance liquid chromatograph (Agilent Technologies, Germany). An AB Sciex QTrap 3200 MD triple quadrupole mass spectrometer (AB Sciex, Singapore) with an electrospray ion source (Turbo V with a TurboIonSpray probe) was used as a detector. Selectivity, carry over, linearity, accuracy, precision, ma-trix effectand recovery were evaluated for the developed method. Results. A method of HPLC-mass spectrometric determination of valprazolamide in rabbit plasma was developed (Phenomenex Synergi C18 analytical column 4 μm 2.0 × 50 mm, gradient elution: 0–1 minute 10% aqueous acetonitrile solution; 1–3 minutes linear increase in concentration acetonitrile in a mixture up to 90%; 3–4 minutes isocratic section with an acetonitrile concentration of 90%; 4–5 minutes conditioning the column with a 10% solu-tion; flow rate of the mobile phase – 0.6 ml / min; volume of sample injected – 20 μl; total time gradient elution – 5 min t; mass spectrometric detec-tion). Mass detection conditions: positive polarization, voltage of the electrospray 5500.0 V, declustering potential 41.0; the curtain gas pressure is 20.0 psi, the spray gas is 40.0 psi, the input potential is 3.5 V. The MRM transitions for valprazolamide were m/z 256.1 → m/z 130.1 and m/z 81.0. Acetazo-lamide (m/z 223.1 → m/z 73.0) was used as an internal standard. Conclusion. The analytical range of the method for determining valprazolamide is 1–1000 ng/ml. The developed method is selective, accurate, preci-sion and linear, it meets the requirements for the validation of bioanalytical methodsin all respects.